psychology research about dreams

July 26, 2011

The Science Behind Dreaming

New research sheds light on how and why we remember dreams--and what purpose they are likely to serve

By Sander van der Linden

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For centuries people have pondered the meaning of dreams. Early civilizations thought of dreams as a medium between our earthly world and that of the gods. In fact, the Greeks and Romans were convinced that dreams had certain prophetic powers. While there has always been a great interest in the interpretation of human dreams, it wasn’t until the end of the nineteenth century that Sigmund Freud and Carl Jung put forth some of the most widely-known modern theories of dreaming. Freud’s theory centred around the notion of repressed longing -- the idea that dreaming allows us to sort through unresolved, repressed wishes. Carl Jung (who studied under Freud) also believed that dreams had psychological importance, but proposed different theories about their meaning.

Since then, technological advancements have allowed for the development of other theories. One prominent neurobiological theory of dreaming is the “activation-synthesis hypothesis,” which states that dreams don’t actually mean anything: they are merely electrical brain impulses that pull random thoughts and imagery from our memories. Humans, the theory goes, construct dream stories after they wake up, in a natural attempt to make sense of it all. Yet, given the vast documentation of realistic aspects to human dreaming as well as indirect experimental evidence that other mammals such as cats also dream, evolutionary psychologists have theorized that dreaming really does serve a purpose. In particular, the “threat simulation theory” suggests that dreaming should be seen as an ancient biological defence mechanism that provided an evolutionary advantage because of  its capacity to repeatedly simulate potential threatening events – enhancing the neuro-cognitive mechanisms required for efficient threat perception and avoidance.

So, over the years, numerous theories have been put forth in an attempt to illuminate the mystery behind human dreams, but, until recently, strong tangible evidence has remained largely elusive.

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Yet, new research published in the Journal of Neuroscience provides compelling insights into the mechanisms that underlie dreaming and the strong relationship our dreams have with our memories. Cristina Marzano and her colleagues at the University of Rome have succeeded, for the first time, in explaining how humans remember their dreams. The scientists predicted the likelihood of successful dream recall based on a signature pattern of brain waves. In order to do this, the Italian research team invited 65 students to spend two consecutive nights in their research laboratory.

During the first night, the students were left to sleep, allowing them to get used to the sound-proofed and temperature-controlled rooms. During the second night the researchers measured the student’s brain waves while they slept. Our brain experiences four types of electrical brain waves: “delta,” “theta,” “alpha,” and “beta.” Each represents a different speed of oscillating electrical voltages and together they form the electroencephalography (EEG). The Italian research team used this technology to measure the participant’s brain waves during various sleep-stages. (There are five stages of sleep; most dreaming and our most intense dreams occur during the REM stage.) The students were woken at various times and asked to fill out a diary detailing whether or not they dreamt, how often they dreamt and whether they could remember the content of their dreams.

While previous studies have already indicated that people are more likely to remember their dreams when woken directly after REM sleep, the current study explains why. Those participants who exhibited more low frequency theta waves in the frontal lobes were also more likely to remember their dreams.

This finding is interesting because the increased frontal theta activity the researchers observed looks just like the successful encoding and retrieval of autobiographical memories seen while we are awake. That is, it is the same electrical oscillations in the frontal cortex that make the recollection of episodic memories (e.g., things that happened to you) possible. Thus, these findings suggest that the neurophysiological mechanisms that we employ while dreaming (and recalling dreams) are the same as when we construct and retrieve memories while we are awake.

In another recent study conducted by the same research team, the authors used the latest MRI techniques to investigate the relation between dreaming and the role of deep-brain structures. In their study, the researchers found that vivid, bizarre and emotionally intense dreams (the dreams that people usually remember) are linked to parts of the amygdala and hippocampus. While the amygdala plays a primary role in the processing and memory of emotional reactions, the hippocampus has been implicated in important memory functions, such as the consolidation of information from short-term to long-term memory.

The proposed link between our dreams and emotions is also highlighted in another recent study published by Matthew Walker and colleagues at the Sleep and Neuroimaging Lab at UC Berkeley, who found that a reduction in REM sleep (or less “dreaming”) influences our ability to understand complex emotions in daily life – an essential feature of human social functioning.  Scientists have also recently identified where dreaming is likely to occur in the brain.  A very rare clinical condition known as “Charcot-Wilbrand Syndrome” has been known to cause (among other neurological symptoms) loss of the ability to dream.  However, it was not until a few years ago that a patient reported to have lost her ability to dream while having virtually no other permanent neurological symptoms. The patient suffered a lesion in a part of the brain known as the right inferior lingual gyrus (located in the visual cortex). Thus, we know that dreams are generated in, or transmitted through this particular area of the brain, which is associated with visual processing, emotion and visual memories.

Taken together, these recent findings tell an important story about the underlying mechanism and possible purpose of dreaming.

Dreams seem to help us process emotions by encoding and constructing memories of them. What we see and experience in our dreams might not necessarily be real, but the emotions attached to these experiences certainly are. Our dream stories essentially try to strip the emotion out of a certain experience by creating a memory of it. This way, the emotion itself is no longer active.  This mechanism fulfils an important role because when we don’t process our emotions, especially negative ones, this increases personal worry and anxiety. In fact, severe REM sleep-deprivation is increasingly correlated to the development of mental disorders. In short, dreams help regulate traffic on that fragile bridge which connects our experiences with our emotions and memories.

Are you a scientist who specializes in neuroscience, cognitive science, or psychology? And have you read a recent peer-reviewed paper that you would like to write about? Please send suggestions to Mind Matters editor Gareth Cook, a Pulitzer prize-winning journalist at the Boston Globe. He can be reached at garethideas AT gmail.com or Twitter @garethideas .

How scientists are studying dreams in the lab

Neuroimaging, sleepwalking, coin tosses.

By Angela Chen

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Once, studying dreams was the domain of mystics, prophets, and a certain sex-obsessed Austrian psychoanalyst. With neuroimaging techniques and better technology, dreams have become a focus of scientific research, from efforts to record dreams to studies investigating how lucid dreaming might be beneficial to mental health.

Journalist Alice Robb is the author of Why We Dream: The Transformative Power of Our Nightly Journey . The Verge spoke with Robb about theories of dreams, the most provocative studies, and the many questions that remain in the field.

This interview has been lightly edited for clarity.

Can you start by giving me a brief intellectual history of dreams? Before our modern scientific understanding, what were people’s theories of dreams?

If you look throughout history, you see people taking dreams really seriously. Dream diaries are some of the oldest examples of literature, and dreams in the Bible are often treated as prophetic. In the late 19th and early 20th century, Freud comes along and puts dreams at the center of psychoanalysis, arguing that they’re the royal road to the unconscious, and analysts should ask patients about them, and by unpacking them, you can get to the core of a patient’s issues. You see the idea taking off. On the flip side, Freud also said that dreams are all about sex — “a room represents a woman because it has an entrance” — which perhaps didn’t do dreams a favor.

Another part of the story is that the science of sleep is relatively new. Rapid-eye movement (REM) sleep was only discovered in the 1950s. And until then, most scientists thought that sleep was just a time when your brain turned off, and there wasn’t much to study. Or even if there was, they didn’t have a way to study it. So a big part of the story is also advances in technology and neuroimaging enabling us to study sleep and dreams. And now, you see people becoming much more aware of sleep as important for health, and so dreams and sleep are going to the lab.

From a very reductionist, neuroscientific point of view, what’s happening in the brain when we dream? What’s the difference between dreams at night and daydreaming and fantasy?

It’s time when the frontal lobe, the logic centers, are less activated. There’s less rational thinking. At the same time, dopamine is surging and people are often having intense emotional experiences.

Daydreaming, mind wandering, night dreaming — you can think of them as all on a spectrum. They are all involving the default mode network, the part of the brain that gets involved when everything else has quieted down, and you’re not actively engaged in something. Both mind-wandering and daydreams are involving the medial prefrontal cortex and medial temporal lobe. During REM dreams, you’re also the visual cortex so you’re having these more intensely visual experiences. Sight is the sense that’s more involved than, say, hearing or smell or touch.

Do people really smell things in dreams? I don’t believe I have, though I also generally have a weak sense of smell.

I do think smell is rare in dreams. I don’t have a stat off the top of my head, but dreams are predominantly visual, even for people who are blind, depending on what age they lost their sight. If they lost their sight after around the age of five, they can experience sight in dreams.

Nowadays, what are the main psychological theories for dreams? I’m assuming Freud is no longer in fashion?

Certain ideas of Freud’s have been borne out. One idea is that you are dreaming about things you are suppressing during the day, and there is actually research on something called the “ dream rebound effect .” The psychologist Daniel Wegner found that if people were told not to focus on something before going to bed, they’re more likely to dream about it. He told one group of students to focus on a target person before bed and told another group of students about this target person and found that the group that was trying to avoid those thoughts were actually reporting more dreams about the person.

There’s a theory from evolutionary psychology that’s pretty popular, and it argues that dreams have a survival function. They give us a chance to practice for things we’re stressed out about in real life. That would explain why dreams are predominantly negative. Dreams tend to be much more about anxiety than about pleasure and involve a lot of intense feelings and fear. The idea is that we wake up, and we’re more prepared to tackle the things we faced in our nightmares. That would also maybe explain why dreams tend to involve more primal settings. There are a lot of actions like running around and being chased, elaborate themes that don’t have much to do with our lives if we live in cities. We’re less likely to have dreams about reading and writing and activities that are more recent developments.

What tools are scientists using to study dreams? Do you have favorite studies?

There are a lot of indirect ways that scientists have found to study dreams, like studying the actions of sleepwalkers or putting recording devices in people’s rooms and catching the utterances that they make during sleep talking and analyzing the language of that.

Neuroimaging studies and studies of rats with electrodes have been important. Some of the first research on memory consolidation and dreams comes from rat studies. Matt Wilson, who’s at MIT, was trying to study memory in rats as they stepped into a maze. They went back to sleep and he noticed through the monitor that he had happened to leave on that their neurons were firing again, as if they were awake and running through the maze when they were in fact asleep. They’re replaying the path that they’ve taken through the day.

Building off that, other scientists ran an experiment where they released rats into a maze. The rats would run around randomly with no preference for any area. If the scientists gave them pleasurable stimulation while the rats were replaying a certain part of the maze during sleep, when the rat wakes up they tend to gravitate more toward that place.

Are there certain big questions that everyone in the field is trying to work on?

There’s definitely a lot of questions that are still unanswered. There’s no formula to determine why we have a certain dream on a certain night, why exactly we’re pulling different memories and mixing them up in the way that they appear.

There’s some really interesting new efforts to improve our ability to record dreams. One of the things that has held dream research back is that they’re so hard to study. Either you are asking people what they dreamed about, which obviously isn’t a perfect way to collect data, or you’re doing brain scans that you can only see, you can’t correlate perfectly to the actual dream content.

There was a Japanese study a few years ago where a group was actually able to create a very crude dream reading device . They scanned people’s brains while they were awake and thinking about certain objects and characters — like a man, a woman, computer, food — and then were able to look at those patterns and match them loosely to what they were thinking about when they were asleep. That correlated pretty well with the subject’s own dream reports.

There’s also a handful of researchers focusing on lucid dreaming. Scientists are looking at how we can induce lucid dreams more reliably, as well as clinical applications of lucid dreaming. I met one woman who used her lucid dreams to hypnotize herself and tell herself that she wouldn’t be anxious anymore. She said that had a positive effect on her waking state.

Another question is: if you rehearse for something in a lucid dream, how does that compare to practicing a task while you’re awake? There was one small study where students had a task tossing a coin in a cup and taking that and trying to have a lucid dream about that to see how effective that was .

That’s interesting, though I hate the idea that now I should be working in my dreams, too. What was the result of coin study?

Forty people tried to toss a coin into a cup about six feet away, and then, afterward, one group was allowed to practice in waking life, another tried to practice in a lucid dream and a control group did nothing. Practicing in real life helped the most, then the lucid dreaming group.

Dream research is typically considered a bit woo-woo. Do you feel like dream researcher is moving into the mainstream?

Dream researchers are definitely gaining more and more respectability, and it’s becoming a legitimate topic of study, as it deserves to be. But it’s still hard to get around the fact that dreams lend themselves to some theorizing that not all areas of study do. For example, I went to a conference in the Netherlands called the International Association for the Study of Dreams that has both people who are hard scientists and also people leading groups for dream analysis. It can be hard to disentangle the science from some of the more mystical ideas.

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• Open access
• Published: 02 October 2023

Evidence for an emotional adaptive function of dreams: a cross-cultural study

• David R. Samson 1 , 2 ,
• Alice Clerget 3 ,
• Noor Abbas 1 ,
• Jeffrey Senese 1 ,
• Mallika S. Sarma 4 ,
• Sheina Lew-Levy 5 ,
• Ibrahim A. Mabulla 6 ,
• Audax Z. P. Mabulla 6 ,
• Valchy Miegakanda 7 ,
• Francesca Borghese 3 ,
• Pauline Henckaerts 3 ,
• Sophie Schwartz 3 ,
• Virginie Sterpenich 3 ,
• Lee T. Gettler 8 ,
• Adam Boyette 5 ,
• Alyssa N. Crittenden 9 &
• Lampros Perogamvros 3 , 10 , 11  

Scientific Reports volume  13 , Article number:  16530 ( 2023 ) Cite this article

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• Anthropology

The function of dreams is a longstanding scientific research question. Simulation theories of dream function, which are based on the premise that dreams represent evolutionary past selective pressures and fitness improvement through modified states of consciousness, have yet to be tested in cross-cultural populations that include small-scale forager societies. Here, we analyze dream content with cross-cultural comparisons between the BaYaka (Rep. of Congo) and Hadza (Tanzania) foraging groups and Global North populations, to test the hypothesis that dreams in forager groups serve a more effective emotion regulation function due to their strong social norms and high interpersonal support. Using a linear mixed effects model we analyzed 896 dreams from 234 individuals across these populations, recorded using dream diaries. Dream texts were processed into four psychosocial constructs using the Linguistic Inquiry and Word Count (LIWC-22) dictionary. The BaYaka displayed greater community-oriented dream content. Both the BaYaka and Hadza exhibited heightened threat dream content, while, at the same time, the Hadza demonstrated low negative emotions in their dreams. The Global North Nightmare Disorder group had increased negative emotion content, and the Canadian student sample during the COVID-19 pandemic displayed the highest anxiety dream content. In conclusion, this study supports the notion that dreams in non-clinical populations can effectively regulate emotions by linking potential threats with non-fearful contexts, reducing anxiety and negative emotions through emotional release or catharsis. Overall, this work contributes to our understanding of the evolutionary significance of this altered state of consciousness.

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Introduction

Why do humans dream? As a product of the brain’s neurophysiology, our species can produce hallucinatory experiences during sleep. These dream experiences represent an altered state of consciousness. Why is it that we exhibit this altered state of consciousness rather than experiencing sleep in total perception quiescence? Research investigating dream content reveals that the dream state of consciousness, which is most often expressed in rapid-eye movement (REM), appears to be preoccupied with world simulation with content often reflecting the self’s social realities 1 , 2 , social networks 3 , 4 , and dangers 5 . Yet, whether dreams could enhance cognitive, affective, or social adaptation has been a question of active debate for decades.

A common framework for explaining the function of dreams is provided by simulation theories , which are based on the premise that dreams have a biological function and reflect selective pressures and fitness enhancement in the evolutionary past via altered states of consciousness 6 . Accordingly, dreams are credible real-world analogs 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 that prime the individual for corresponding contexts encountered in waking life. From this perspective, it has been argued that the phenotypic expression of dreaming could meet the necessary criteria for evolution by natural selection 15 .

Dream simulation and emotion regulation

Emerging work integrating neuroscience and dream content analysis suggests that emotional experiences are a crucial part of the virtual-world simulation of dreams and support an adaptive process that contributes to the resolution of emotional distress and preparation for future affective reactions 6 , 16 , 17 , 18 , 19 . In this context, the threat simulation theory 6 and social simulation theory 9 posit that dreams are biased to simulate threatening and social situations respectively. Such a mechanism would, in turn, promote adjusted behavioral responses in real-life situations 5 , 9 . Other studies have also supported the idea that past negative memories are reprocessed and combined in dreams with new, realistic, and safe contexts, suggesting the possibility of desensitization 20 , 21 or extinction 17 functions for dreaming. Functional dreams could thus expose us to threatening situations while providing us with efficient solutions to these situations. Such a process may facilitate the resolution of current social and emotional internal conflict 16 , 22 , a process also called emotional catharsis 23 , and the reduction of next-day negative mood 24 .

Together, these proposals and empirical observations suggest a potential core function of dreams via simulating distress in a safe environment to help process threats in beneficial ways; as such, functional dreams would strongly contribute to efficient emotion regulation in wakefulness 18 . These mechanisms seem to be impaired in clinical populations, such as patients with nightmare disorder 17 , 25 and anxiety disorders 26 —two pathologies characterized by less efficient fear extinction 17 , 27 .

Indeed, anxiety is considered a maladaptive emotional response implicating dysfunction of inhibitory (extinction) learning 27 , and the persistence of the fear response across time. We would thus expect that dreams with high levels of anxiety and negative emotions in the presence of a threat, as those found in clinical populations, would not serve the emotional processing function of dreams, as no emotional resolution is achieved. Critically, Revonsuo posited that the adaptive emotional function of dreams may be particularly relevant to contemporary small-scale societies facing routine ecological risks such as infectious disease and predation, as the emotional simulating mechanism would be fully activated in the face of the kinds of challenges within their environment 6 . Although there is some preliminary evidence for this argument 5 , 28 , 29 , such arguments have yet to be comparatively tested with large, multicultural datasets.

The importance of cross-cultural testing of dream content

The major challenge to the scientific investigation of dream function remains a sampling problem. To date, most dream studies have been conducted in the Global North—and primarily in the U.S. and European settings with samples of limited socio-economic and racial/ethnic breadth. Thus, one critical challenge to overcome limitations in past dream-based research, is to test the function of dreams by generating dream content variation among diverse populations’ socio-ecological experiences. This may be due in part to the interest of sleep researchers in pairing such work with sleep-based physiological techniques (i.e. polysomnography) that have been historically limited to lab settings (but see 30 for field-based methods in human biology and sleep research that are gaining momentum). While historically dreams have been the subject of anthropological investigation 28 , 31 , 32 , 33 , this ethnographic work is largely descriptive. Hence, much of the dream data are generated from studies that represent a very narrow range of human experiences for select populations (e.g., college undergraduates) at specific historical moments (e.g., between 1970 and 1990) in particular locations (e.g., U.S., Europe) and under similar societal and economic contexts (e.g., educated, high income).

There is a dearth of direct empirical tests of the evolutionary function of dreams, including comparative perspectives that would enable us to assess variation across cultural and ecological contexts in relation to dream content 9 . For example, smaller-scale societies that engage in mixed-subsistence foraging (i.e., hunt and gather for a large part of their diet), often differ from other smaller-scale societies in important ways. The depth and breadth of egalitarianism (i.e., cultural values and practices aimed at the treatment of all individuals as equal, often with norms around avoidance of prestige and hierarchy) in many sub-tropical foraging populations is intertwined with norms of cooperative pooling of time and energetic resources, such as to help provision and care for children 34 , 35 , 36 , 37 , 38 , 39 . Such forms of egalitarianism and extensive cooperation in resource sharing and family life are thought to be critical to survival and reproduction.

In contemporary populations, including the Hadza of Tanzania and BaYaka of the Republic of the Congo forager communities we focus on here, these cooperative subsistence and social dynamics necessarily place a strong emphasis on the importance of face-to-face supportive relationships for day-to-day health, well-being, and even survival 35 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 . These communities share some broad socioecological similarities in terms of (i) continuous environmental exposure to key stimuli—such as ambient light and temperature cues—known to drive circadian entrainment (e.g., circadian driven fluctuations have been shown to influence central characteristics of dream reports 50 ), (ii) gender divisions of foraging and household labor (though varying in their intensity between the BaYaka and Hadza), (iii) ecological risk in the form of predation exposure by way of large animals, pathogens and parasites, and (iv) norms regarding egalitarianism and generous resource sharing behaviors 39 , 40 , 41 , 42 , 43 , 44 , 51 , 52 .

The community-oriented interpersonal behaviors characteristic of BaYaka and Hadza and their maintenance require high degrees of emotion regulation and social problem solving. Unlike the experience of many individuals in populations from the Global North, these foragers’ daily interactions are repeated with the same network of cooperative partners throughout their lives. Additionally, although precise estimates are difficult to assess, mortality rates are relatively higher in subsistence-level societies compared to populations with better access to emergency care and biomedical treatment 41 —a factor that may be relevant in evaluating the possible threat simulation function of dreams. Thus, foragers may experience greater threat and community oriented responses to threat in their dreams. If an adaptive function of dreams is to reinforce or rehearse such day-to-day, prosocial (i.e., community-oriented) interactions, particularly with trusted kin, then people in BaYaka and Hadza communities will have a higher representation of those interactions and family members in their dreams than would typical populations in the Global North who reside in more individualistic societies.

Hypotheses and predictions

Here, we compare the dreams of two foraging communities—the BaYaka and Hadza—to non-clinical and clinical (i.e., with nightmares and social anxiety) populations from the Global North. First, because of their strong egalitarian social norms and high levels of daily face-to-face interpersonal support from trusted family and friends, we predict that the dream content of both forager groups will have a greater frequency of community-oriented behaviors when compared to dreamers in the Global North. Second, given that both forager groups experience greater early-to-midlife mortality—subsequently leading to a greater chance of an individual losing their own life, the life of offspring, kin, or friends—we predict a greater frequency of threat related dream content relevant to mortality. Third, we expect that foragers’ dreams will serve an efficient emotion regulation function, where threats are associated with new, non-fearful contexts/efficient solutions 17 , and, thus, with lower anxiety/negative emotions in dreams. Finally, we predict that the Nightmare group will have greater levels of negative emotions in dreams and that the student group, associated with COVID-19 pandemic, as well as the social anxiety group, will be characterized by greater anxiety in dream content. By comparing these groups, we can better understand the role of culture and environment in shaping the human experience of dreaming.

Material and methods

Participants.

In all, individuals from two sub-Saharan foraging egalitarian communities with low degrees of market integration, the Hadza and BaYaka and from three high income capitalistic populations (including non-clinical and clinical populations) totaling 234 participants contributed 896 dreams (see Table 1 for summary details).

Global North data collection and characteristics

Data from the Global North populations were drawn from previously published studies done in Switzerland, Belgium, and Canada. The Switzerland and Belgium samples were generated between 2014 and 2022 25 , 26 , 53 , 54 , 55 and included data from three groups: a non-patient group of young healthy participants, patients suffering from social anxiety disorder (SAD), and patients suffering from nightmare disorder. Participants in these studies all kept the same sleep and dream diary (for details see 18 ). During the night or every morning, upon spontaneous awakening, the participants were asked to report whether they had a dream with or without recall or no dream at all. They also reported the presence of specific emotions thanks to dichotomous questions (presence/absence); in total, eleven emotions could be reported. A twelfth choice was reserved to the “absence of emotions”. In the last section of the dream diary, they were also asked to freely write down the dreams they had experienced during their sleep.

The non-clinical reference control group in the Global North includes 219 participants (123 females). A subset of 103 participants, aged between 16 and 40 years old (M = 22.1, SD = 7.9), had dream word counts equal to or greater than 20 words and were included in the dream analysis (word average per dream = 78.2, SD = 66.0). All participants followed a constant sleep schedule during the days preceding the experiment to assess the mean sleep duration and exclude any circadian disturbance or sleep disorder. People suffering from mental disorders were excluded. Ethical approval was granted by the committee of the Faculty of Medicine of the University of Liege and by the Ethical Committee of the Canton of Geneva.

Dreams were also collected from patients suffering from social anxiety disorder (SAD) according to The Diagnostic and Statistical Manual of Mental Disorders (DSM5) 26 , 56 . SAD is characterized by a persistent amount of fear when confronted with social situations 57 . Forty-eight subjects (32 females) were included in the final sample, after assessment of their social anxiety disorder level. The dream diary was filled every morning upon awakening for 2 weeks. Three hundred twenty-four (324) dream reports were collected (6.75 dreams per participant). A subset of 37 participants, aged between 16 and 40 years old (M = 24.4, SD =7.9), had dream word counts equal to or greater than 20 words and were included in the dream analysis (word average per dream = 76.9, SD = 56.7). Ethical approval was granted by the Ethical Committee of the Canton of Geneva, Switzerland (“Commission Cantonale d’Ethique de la Recherche sur l’être humain”).

Additionally, dreams were collected in individuals suffering from nightmare disorder 25 . In total, 36 patients (27 females) were included. All of them suffered from nightmare disorder according to DSM5 with at least moderate severity (> 1 episode per week). Every morning upon awakening participants filled in a dream diary for 2 weeks. One hundred thirty-four (134) dream reports were collected (3.72 dreams per participant). A subset of 33 participants, aged from 20 to 35 years old (M = 26.3, SD = 8.4), had dream word counts equal to or greater than 20 words and were included in the dream analysis (word average per dream = 43.5, SD = 23.8). Ethical approval was granted by the Ethical Committee of the Canton of Geneva, Switzerland (“Commission Cantonale d’Ethique de la Recherche sur l’être humain”).

Altogether, the Belgian and Swiss studies had 924 dream reports collected from the dream diary over 397 nights (4.2 dreams per participant on average). Of those dreams the number that were included in the final analysis with words counts equal to or above 20 are as follows: control N  = 356, Nightmare Disorder N  = 113, and SAD  = 184.

Students at the University of Toronto contributed dream reports ( N  = 184) collected during the fourth wave of the COVID-19 pandemic, where the proliferation of COVID-19 variants was of major concern in Ontario, Canada, as announced by the Public Health Agency of Canada (Statistics Canada, 2021). In total, 24 students (21 females) aged from 19 to 25 years old (M = 21.9, SD = 5.5) were included. Ethics was approved and attained by the University of Toronto REB (RIS Human Protocol Number 39768). During this time, self-rated mental health was below national average (< 50%), and 82% of the Canadian population that were eligible for vaccination were fully vaccinated, however restrictions were still imposed in most areas, including mask-wearing, and limiting contacts. Thus, explorations of evolutionary theories on dream functions may have special relevance during the COVID-19 pandemic 58 , 59 . The final number of dreams equal to or above 20 words and included in the analysis was N  = 168 (word average per dream = 120.6, SD = 44.4).

Global South data collection and characteristics

Data were collected over different time periods by different experimenters. Hadza participants ( N  = 18) were surveyed by DRS in January and February of 2016 and BaYaka participants ( N  = 19) by AHB, SLL, VM, and MSS in June and July 2017. Hadza participants were aged between 18 and 68 years old (M = 42.7, SD = 8.5) and BaYaka participants were aged between 27 and 70 years old (M = 42.3, SD = 10). Combined, we collected a total of 101 dream reports (2.16 dreams per participant and a word average per dream = 38.7, SD = 18.9). The Hadza contributed 48 dream reports (female dreams = 12, male dreams = 36; word average per dream = 44.4, SD = 20.6); all Hadza dreams were equal to or greater than 20 words and were included in the analysis. The BaYaka ( N  = 19) contributed 53 dream reports (females dreams = 26, male dreams = 27); twenty-seven BaYaka dreams were equal to or greater than 20 words (word average per dream = 28.7, SD = 9.1) and were included in the analysis.

Dream reports were collected in the field using a modified Most Recent Dream (MRD) method 60 as a template for questionnaires, and in practice (as the indigenous populations could not write) were a daily verbally administered dream diary. The instructions, given by field researchers in morning after a sleep period, requested the participant to recall whether they dreamt the previous night. If subjects answered in the affirmative, they were then asked to recount the details of the dream using the MRD method template. The report was expected to be detailed, including a description of the dream's setting, the people involved (their age, sex, and relationship to the participant), and any animals present in the dream. Participants were also instructed to describe their emotions during the dream and whether it was a positive or negative experience. This method is ideal for use in small-scale societies because it is a fast, inexpensive, and reliable way to obtain large samples of dream reports. For both forager groups, dream content was translated by the aid of a multilingual field assistant at the time the dream was recorded. Importantly, it is essential to note that, as both the MRD modified and verbally administered dream diary (Global South) and the classic Dream Diary method (Global North) recorded dreams of the previous night, they shared a similar approach and were directly comparable. Additionally, both were administered shortly after awakening from sleep on the same day as the dream, thereby minimizing potential memory biases 61 .

For work with the Hadza, IRB approval was granted from the University of Nevada, Las Vegas (2014) and verbal consent for participation was asked to each participant in Swahili, the second language of the Hadza community. All research was performed with approval of the government of Tanzania, via the Tanzanian Commission for Science and Technology (COSTECH) and the Tanzanian National Institute for Medical Research (NIMR). For the BaYaka, village council consent for this study was obtained at a community meeting in 2015. Subsequently, community consent was annually renewed. Verbal consent was provided by each participant following recruitment into this study. Approval to conduct research in the Republic of the Congo was given by The Centre de Recherche et D’Edudes en Sciences Sociales et Humaines. Ethics approval was obtained from Duke University (2017), the University of Notre Dame (2017), and the University of Cambridge (2017).

All methods were performed in accordance with the relevant guidelines and regulations, and informed consent was obtained from all participants.

Dream text analysis

LIWC-22 is an acronym for Linguistic Inquiry and Word Count, and it is a text analysis software program that can return results for up to 90 different variables or categories 62 . The English text analysis strategy employed the LIWC-22 Dictionary. This internal dictionary is comprised of over 12,000 words, phrases, and emoticons, which have been carefully selected and categorized into sub-dictionaries to assess various psychosocial constructs. Essentially, the LIWC-22 software program is designed to map linguistic constructions to important psychosocial theories and constructs, and thus, target words contained in texts that are read and analyzed by LIWC-22 are used for this purpose.

In this study, the dream texts were translated and transcribed into English, and preprocessed into four super-categories— Community-oriented (by grouping the LIWC categories: social, family, moral, friend, and prosocial) , Threat (by grouping the LIWC categories: conflict and death) , Negative emotions (encompassing the category: negative emotions), and Anxiety (encompassing the category: anxiety). To create an outcome variable for statistical models (see section ‘Modelling' ), we summed the number of words of each category in each dream text. Examples of the Community-oriented target words were: care, help, thank, please, parent, mother, father, baby, honor, deserve, judge, you, we, he, she. Examples of the Threat target words were: fight, killed, attack, death, dead, die, kill. Examples of the Negative emotions target words were: bad, hate, hurt, tired. Examples of the Anxiety target words were: worry, fear, afraid, nervous. The LIWC-22 Dictionary provides a systematic and reliable approach to text analysis 63 and has been widely used in other word-based dream content analyses 25 , 64 , 65 .

To assess the predictors of the four response variable categories ( Community-oriented, Threat, Negative emotions, Anxiety dream content) by population (BaYaka, Hadza, Nightmare, SAD, Students, and Control) we used a linear mixed effects model, built using the lme4 package and model averaged using the MuMin package 66 . To normalize the count data for each category, we square root transformed the response variable 67 , 68 . Finally, we made statistical inferences using a combination of standardized coefficients, confidence intervals, and p-values. We controlled for the fixed effects of age, number of dream reports, word count and sex as well as subject ID (to control for repeated measures) as a random effect. After assessing information criterion, models including the number of dream reports and age as fixed effects differed little from models without them, and so we removed them from final analysis. To increase the power of the model to identify the predicted patterns in the data, we obtained coefficients based on optimization of the log-likelihood using shrinkage, which incorporates measurement error into the regression model and improves less certain estimates by pooling information from more certain estimates 69 .

The non-patient sample from the Global North was used as a model reference category (i.e., a group that is used as a point of comparison for other groups in a statistical analysis) so effect-size estimates for each population are predicted differences in counts of dream content compared to this sample.

The dream content models were fit as follows:

The full dataset, along with all meta-data and more detail of each variable, is available in the Open Science Framework (OSF) data repository:  https://osf.io/7n6kf/ .

Community-oriented’ dream content is greatest in BaYaka

Amongst all sampled populations, the BaYaka showed greater community-oriented dream content than all group samples from Global North populations and Hadza population, after adjusting for sex, word count, and subject ID. As shown in Table 2 , and displayed in Fig.  1 , after factor correction, the BaYaka sample positively drives community-oriented dream content. Additionally, women’s dream reports and word count were drivers of the response variable (Table 2 ). As ethnographic data, we present a few such examples here:

‘I was walking in the forest with my two adult daughters and found a porcupine in a trap and brought it back to the village to eat it. It was a good dream’ ‘I was net hunting with my family (including extended family camp) and we caught many animals so he had to make a smoker "bota" to smoke all of them’

Prosocial dream estimates plot.

‘Threat’ dream content is greatest in BaYaka and Hadza

After adjusting for sex, word count, and controlling for repeated measures of the subject ID, both the BaYaka and Hadza samples had higher levels of threat dream content compared to the Global North groups. This is shown in Table 3 and depicted in Fig.  2 . Thus, belonging to the BaYaka or Hadza community is associated with a greater probability of experiencing threatening dream content. No other factors were found to significantly influence threat dream content.

Threat dream estimates plot.

Importantly, several dream reports gathered among the Hadza community demonstrated high threat situation to which a positive, emotionally cathartic resolution was found. For example:

‘I dreamt I was being chased by a herd of elephants; I was in Nyanza, which is open flat savanna land. I ran and found a small cave which was too small for the elephants to follow. I escaped’. ‘I was chased by an elephant in the bush around camp. I was with four unfamiliar women. I escaped by running into the mountains’. ‘I dreamt I was in the forest and the military was chasing me with guns and he climbed a tree to get away.’ ‘I was chased by a leopard in nearby mountains. I began by hunting but realized that I was the hunted. I was alone but I escaped’.

Moreover, in some Hadza dream reports, a solution to a threat was found through social support:

'I dreamt I fell into a well that is near the Hukumako area by the Dtoga people. I was with two others and one of my friends helped me get out of the well.' ‘I dreamt a buffalo hit me. I was in Numbeya bushland where we look for honey. I was looking for the "small honey". There was another man called January and he came and helped me’ ‘I dreamt a Toga not from this camp (who) took a knife and a person he didn't know from another camp. After I told the guy to stop, he left our Sengele camp.’

'Negative emotion’ dream content is greatest in Nightmare disorder sample

After adjusting for sex, word count, and subject ID, the sample of patients from the Global North in the Nightmare Disorder group had higher levels of dream content with negative emotions compared to the reference group (Table 4 and Fig.  3 ). Conversely, the Hadza exhibited significantly fewer negative emotion words in their dream content than the reference group. No other groups differed from the reference group, as shown in Table 4 and depicted in Fig.  3 . The following dream reports demonstrate high fear without resolution in the Nightmare Disorder group:

‘My mom would call me on my phone and ask me to put it on speakerphone so my sister and cousin could hear. Crying she announced to us that my little brother was dead. I was screaming in sadness and crying in pain.’ ‘I was with my boyfriend, our relationship was perfect and I felt completely fulfilled. Then he decided to abandon me, which awoke in me a deep feeling of despair and anguish.’ ‘I remember in my dream is that I was sitting at a table, in one of the secret rooms, across from a middle-aged man who said he was my uncle (he did not look like any of my uncles), and he was over 100 years old but looked like he was in his 50s. He looked like evil characters from movies. He said he was going to kill me after he went to speak with other people in the other room to admit his secret and then come to kill me. After he left the room, I got up and saw that the door was not fully closed. My thought was that I had to go fight him and then I woke up before I could approach the door.

Negative emotions dream estimates plot.

‘Anxiety’ dream content is greatest in the Canadian (COVID-19 pandemic era) student sample

After accounting for sex, the word count and participant repeated measures by subject ID, it was found that the student group had more anxiety dream content compared to the reference group. Table 5 and Fig.  4 indicate that no other groups demonstrated a significant difference from the control group. In the following two examples, the dream scenario illustrates the level of anxiety that the subject experiences as he needs to confront challenges alone:

‘The dream I remember relates to a game that I play. As it only involved myself, there was no one that I knew around, and I remember feeling anxious. I was doing a very difficult mini-game in the game where a bunch of non-player characters were all around me and I needed to hide behind obstacles to stay safe. I remember waking up once I died inside the mini-game’

Anxiety dream estimates plot.

Contrary to one of our predictions, no significant differences between the non-clinical group and the Social Anxiety Disorder group were found about the level of anxiety experienced in dreams. However, some dreams illustrate the social isolation these patients are experiencing in their real life, translated by a lack of social support when dangers arise:

‘I was in an elevator, stuck, alone. I pressed the down button, and then the elevator sped down. I was very scared, I tried to set off the emergency bell. I arrived at the bottom, it was dark and a sheet or blanket fell from the ceiling of the elevator to cover me.’

In other dreams of this group, people are regarded as hostile, which eventually increases the anxiety level:

‘I dreamed that I ran into someone I knew at the supermarket. We collided without excusing each other which led to an open conflict. The person in question threatens me, I go to the manager of the store accusing the person of having stolen something (it's not true). Then we walk out of the store and the other begs me to drop my charge of theft. I tell him that I won't go any further and that the newspapers won't know anything because I'm a journalist. The person's mother picks him up. I walk a bit until we go to their place. I explain to the person that I have the feeling of being followed by a man who looks like a shadow, and who watches over me and waits for the moment to seize me. I then understand that this man is death himself!’ ‘In my dream, I was at my high school. I went into the classroom by myself and two friends (female, 18) that I thought were close to me started isolating me during group work. I worked by myself the entire class while they acted aggressively towards me, at least verbally. I pulled out my chair to go submit my assignment and it hit a person behind me (male, 18). This person is a friend from my primary school. He shouted at me even though I tried to explain to him what happened was just an accident. I used the washroom, and my phone was water-damaged by one of the two girls (may or may not be an accident). I asked her to pay me back, but subconsciously I did not want the refund but instead to have an excuse to hold a conversation with her. It was an unpleasant dream because I thought I was close to them.’

In the present study, we tested the hypothesis that dreams serve an emotional function that is potentially adaptive by examining dream content from Hadza and BaYaka foragers, who belong to communities characterized by high levels of interpersonal support coupled with greater early-to-midlife mortality (due to predation, resource stress, food and water insecurity, and disease) in comparison to populations in the Global North. We found partial support to the first prediction, that forager dreams exhibit greater community-oriented dream content. Of all the populations examined, only BaYaka reported dreams with significantly more frequent content related to community-orientation and social support amongst family and friends (Table 2 and Fig.  1 ).

The second prediction, that foragers’ dreams contain more threat related content was supported. Both the BaYaka and Hadza samples demonstrated a greater frequency of mortality and conflict associated dream content compared to the reference group, whereas the other groups did not show such difference (Table 3 and Fig.  2 ). The prediction that dreams may augment the processing of high threat levels, yet also be characterized by low levels of both anxiety and negative emotions—was supported. The BaYaka exhibited levels of negative emotions in dreams that did not differ from the reference group, while the Hadza exhibited significantly less dream content with negative emotions compared to the reference. As expected, the Nightmare Disorder group also exhibited significantly greater levels of negative emotions in dreams (Table 4 and Fig.  3 ). A similar pattern was found with anxiety dream content, where the student group during the COVID-19 pandemic was characterized by significantly greater anxiety dream content compared to the reference group, while the BaYaka and Hadza did not differ compared to the reference group (Table 5 and Fig.  4 ).

Evidence for an emotional function of dreams in small-scale forager populations

BaYaka and Hadza foragers face several specific hazards. BaYaka communities reside in a rainforest ecology in the Congo Basin, where routine hazards (i.e., specific sources of danger include: (i) intergroup conflict with Bantu fisher-farmers due to perceived trade and labor related debt, (ii) illnesses (malaria, tuberculosis, intestinal parasites), and (iii) extrinsic risks (i.e., broader factors that can increase a person’s overall risk of harm or negative outcomes) of everyday life, including encounters with dangerous animals like snakes, elephants, crocodiles, and gorillas while hunting, fishing, and foraging as well as other hazardous aspects of the forest such as falling limbs/trees and falls while climbing 70 . The BaYaka infant mortality rate in the study region is unknown, but (as measured elsewhere in the region) can be inferred to be around 20 percent 41 . Adult and juvenile mortality is generally relatively high compared to populations with better access to emergency care and biomedical treatment, though precise estimates are currently unknown 41 . A study of death among the Aka in the Central African Republic found that infections and parasitic diseases were the most common causes of death across ages, causing 22 percent of 669 deaths, and diarrhea causing another 21 percent of deaths 71 .

The Hadza reside in a diverse ecological region characterized by rolling hills, grasslands, and acacia commiphora woodland. Hazards for the Hadza include (i) intergroup conflict with the Datoga pastoralists who co-reside in some areas of the landscape and keep large herds of cattle and goats that drink the scare water in the water holes during the dry season and eat much of the vegetation needed to support wildlife, (ii) illnesses (e.g. tuberculosis, malaria, viral diarrhea) that are faced with little access to biomedical treatment, and (iii) extrinsic risks of everyday life that include falling from trees when collecting honey, snakebites, and encounters with predators when hunting or scavenging meat 48 . One study showed that out of 75 deaths, a third of deaths were attributed to illness, with age, childbirth, poisoning or bewitching and homicide, and falling from trees as other causes of death 72 . With respect to mortality, 21% of infants die in the first year of life and 46% of juvenile children die by age 15 72 , 73 .

Comparatively, populations of the Global North face other types of threats and share different sociocultural values than individuals from small-scale societies. In contrast to collectivistic cultures, like BaYaka and Hadza, most societies of the Global North are strongly individualistic and competitive 74 . People in these societies have less routine face-to-face contact with and imperative cooperative reliance on broad kin networks. At the same time, this individualism shapes many common threats, which are mostly connected to social life (e.g., ostracism and exclusion, loss of status, shame, failure in an exam, etc.), and which are mostly experienced at an individual rather at a collective level. Although recent austerity plans resulted in the reemergence of unemployment, poverty, homelessness, and food insecurity in European and American countries 75 , economic development, public health infrastructure, and access to biomedical care have been linked to comparatively greater life expectancies in the Global North (e.g. 77 years in the U.S. and 80 years in the E.U.), with a larger proportion of deaths occurring in older age from chronic conditions 76 , 76 , 78 .

The present findings provide evidence that when compared to populations in the Global North, foragers disclose a prevalence of community-orientation in their waking life as well as the socially connected themes in their dreams, which may support emotional health. Specifically, our analysis suggests that even in the context of threat, community-orientation—expressed by strong social networks that rely daily on mutual assistance in the context of strong egalitarian social norms—may also play an important role in providing strategies to overcome threats and ultimately achieve emotion regulation. Importantly, an interpretation of BaYaka and Hadza dreams is that foragers activate both the threat simulation and extinction functions of dreaming, which may result in resolution of these threats within their dreams.

The dysfunctional nature of nightmares

We claim here, in line with other theoretical concepts 17 , that increased threat in dreams (as compared to dreams from healthy controls) does not seem to be functional without a subsequent emotional resolution. For example, patients with nightmare disorder have dreams characterized by recurrent, intense, and highly threatening content that cause significant distress and impairment in social, occupational, or other areas of functioning 56 . Nightmares are dreams with high threat but insufficient emotional resolution. The dreamer cannot find effective solutions for threats, therefore high fear and anxiety impedes emotion regulation and catharsis. According to the threat simulation theory, individuals possess a threat simulation system by which multiple factors (such as, inherited personality traits, threat input throughout adolescent development, current stress levels and recent threat input) regulate dream phenotypes. These inputs can also be attenuated by strong social support networks and egalitarian norms. Previous work has suggested that threatening content in dreams ultimately serve to strengthen waking threat perception skills and threat avoidance behaviors that help to self-cope with the challenging realities of waking life 6 , 8 , 79 , 80 .

The forager data further supports the idea that overcoming threat by way of adaptive emotional responses (in wake or sleep) is a crucial component of an efficient emotion regulation in the face of stressful events. When the presence of threats in dreams is not associated with subsequent emotional resolution, as in recurrent nightmares, dreams seem to lose their emotional processing function. Our results, along with others 81 , 82 , 83 suggest that nightmares are dysfunctional dreams with high threat simulation coupled with lack of fear extinction.

Dreams in situations of social isolation or social anxiety

Contrary to the community-oriented character of the BaYaka population, and similar to the increased negative emotions found in nightmares, the dream reports collected from students during the pandemic era were characterized by high levels of anxiety, and sometimes these manifested with themes of isolation and having to confront challenges alone (as depicted in the dream text examples in the “ Results ” section). For example, dreamers experienced high anxiety because of the presence of hostile people in the narrative, without finding any positive way to deal with such a threat. Our results suggest that dreams of individuals in situations of social isolation or social anxiety do not seem to achieve a sufficient degree of emotional resolution (see also 26 ). Whether there is a causal relationship between such a deficient extinction function of dreaming and the symptomatology of anxiety disorders is not clearly elucidated and should be further tested in the future.

Limitations

There are several limitations to the current study, particularly in regard to the dream content collection among the BaYaka and Hadza populations. Future dream research in such small-scale societies should emphasize not only generating dream data but also including daily reports of activity or evidence of daytime emotion regulation or performance 18 . Accounts for waking life experiences enable a direct analysis of dreams to experiences encountered during the day, which would then allow to test threat or social simulation hypotheses or to make claims related to these hypotheses in general 60 . Correlational studies, such as the one conducted by Sterpenich and colleagues 18 , or interventional studies (i.e., manipulating dream content and observing its effect in wakefulness 25 ) offer a closer approximation of the relationship between wake and dream functions. Importantly, observational dream research, including the present study, cannot claim to provide strong evidence for causality between wakefulness and dreams, nor for the directionality of such relationship regarding emotion regulation functions. Finally, as both a point of originality for this work and in distinction from previous work, this study did not test for the daytime emotional state-response, as emotional resolution was assessed in the dream itself.

Dream reports with greater length are more likely to contain sufficient information to accurately describe a dream 29 . Yet, some dream reports from both of these communities were relatively short in length. This can be attributed to dream recounting having to be translated and transcribed into English. Although we made efforts to recount as much detail as possible, dream descriptions could only be paraphrased summaries of dreams distilled through the translator. In addition, it is difficult to assess whether the participant recounting his/her dream was motivated and/or had sufficient practice formulating accurate long-term memories of the dream. Often, inexperienced dream recounters simply answer the questionnaire as is presented to them, which can attribute to dream report bias 80 . Despite the short dream descriptions and less formalized training in dream recounting, the BaYaka and Hadza communities are characterized by a rich storytelling culture and were typically highly motivated to discuss dreams and their interpretations. We also note that these samples are characterized by a stark lack of sexually related activity in dreams. It may well be that for these groups, the lack of recounting dreams of a sexual nature may reflect a taboo placed on descriptions of sexuality in general.

Here we provide support for the idea that in non-clinical populations with real and perceived threats, dreams may process high threat levels, yet also be characterized by low anxiety and negative emotions. Our results suggest indirectly that dreams can effectively regulate emotions by linking potential dangers with novel, non-fearful dream contexts and can lead to a reduction in feelings of anxiety and other negative emotions, as a form of emotional release or catharsis. In addition, in at least one such community (the BaYaka), emotional catharsis is often achieved by strong social support. Ultimately, if dreaming prepares human beings to face likely challenges and dangers in waking life, then our results are among the first to show these potential functions under evolutionarily relevant socio-ecological conditions.

Data availability

The data that support the findings of this study are publicly available on OSF ( https://osf.io/7n6kf/ ). 

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Acknowledgements

We would like to thank both the Hadza and BaYaka for participating in this study. We would like to thank Dambo Justin and Mékouno Paul for assistance with data collection in Congo. We would like to thank Jarno Tuominien for useful discussions and Audrey Theux for technical assistance. This project was funded by the National Geographic Society (no. 9665-15 to DS), the Jacobs Foundation (to LG and AB), the Medical Direction of University Hospitals of Geneva (PRD 18-2019-I to LP) and the Swiss National Science Foundation (CRSK-3_190722 to LP).

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Conceptualization: D.S. and L.P. Methodology, software: D.S., A.C., L.P. Data curation: D.S., A.C., N.A., J.S., M.S.S., S. L-L., F.B., P.H., V.S., L.T.G., A.B., A.N.C., L.P. Writing—original draft preparation: D.S. and L.P. Visualization, investigation: D.S., S. L-L., S.S., V.S., L.T.G., A.B., A.N.C., L.P. Supervision: D.S. and L.P. Funding acquisition: D.S., S. L-L., L.T.G., A.B., A.N.C., L.P. Writing—reviewing and editing: D.S., A.C., N.A., J.S., M.S.S., S. L-L., F.B., P.H., S.S., V.S., L.T.G., A.B., A.N.C., L.P.

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Samson, D.R., Clerget, A., Abbas, N. et al. Evidence for an emotional adaptive function of dreams: a cross-cultural study. Sci Rep 13 , 16530 (2023). https://doi.org/10.1038/s41598-023-43319-z

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5 Common Recurring Dreams and Their Potential Meanings

Have you been having strange dreams lately here's what they might mean..

Posted April 19, 2024 | Reviewed by Tyler Woods

Dreams have long held a certain mystique, captivating humanity with their enigmatic narratives and symbolism. Across both cultures and time, this aspect of our consciousness has been a constant source of fascination and interpretation.

However, through psychological research, both academics and laypeople alike are beginning to unearth the significance of dreams, as well as attempt to grasp their deeper meanings.

Psychological Perspectives on Dreaming

Dreams, arguably one of the most elusive fragments of our subconscious , occur during the rapid eye movement (REM) stage of sleep. While the exact purpose of dreaming remains a long-standing subject of debate, researchers estimate that the average person experiences around four to six dreams per night.

During these nocturnal odysseys, our minds embark on journeys that can be as perplexing as they are revealing. However, similar to the purpose of dreams, their significance and origins have been a perpetual subject of debate.

• Freudian perspectives. Sigmund Freud, the renowned father of psychoanalysis , believed that dreams were the “royal road to the unconscious.” According to Freud, dreams are the gateway to our deepest desires, fears, and conflicts, often obscured from conscious awareness. He proposed the theory of manifest content (the literal narrative of a dream) and latent content (the symbolic meaning) concealed within. Through psychoanalysis, he sought to decode these hidden messages and uncover how our subconscious turmoil shapes our waking lives.
• Jungian perspectives. Carl Jung, another pioneering figure in psychology, offered an alternative perspective on dreams. For him, dreams aren’t a mere random manifestation of the subconscious, but rather a meaningful expression of our psyche’s quest for wholeness. Jung introduced the concept of archetypes—universal symbols that permeate human experience—and suggested dreams to be the channel through which these archetypes manifest. By engaging with our dreams, Jung believed we could make attempts at self-discovery and confront the shadowy aspects of our personalities, integrating them into a cohesive whole.
• Contemporary perspectives. In modern psychology, there are many diverse theories regarding the nature of dreams. Cognitive theories propose that dreams are a byproduct of the brain’s processing of information, serving to consolidate our memories while also reinforcing learning. Neurological research often focuses on the complex mechanisms that underlie our dreams, highlighting the role of brain activity during REM sleep. Although modern perspectives offer valuable insight, they often skirt around the profound symbolism and personal significance that dreams hold for each of us.

Common Dream Symbols and Their Meanings

Dreams are replete with symbolism, each carrying its own significance and resonance for each individual. Research from the journal Motivation and Emotion shows that, across the globe, there are multiple common motifs within our dreams. While interpretations may vary, certain themes recur across cultures and contexts:

• Falling. Likely one of the most ubiquitous dream motifs, dreams of falling often evoke a sense of vulnerability and loss of control. Psychologically, these dreams may symbolize a fear of failure or a perceived descent into personal chaos. Alternatively, falling could also indicate a need to let go of inhibitions and embrace change. Freud interpreted falling as a manifestation of sexual desires or anxieties, reflecting a longing for release or surrender.
• Flying. In stark contrast to falling, dreams of flying represent a soaring liberation from earthly constraints. Psychologically, flying dreams could symbolize freedom, empowerment, and transcendence. Jung viewed flying as a metaphor for spiritual ascent, signifying a journey towards enlightenment. These kinds of dreams often coincide with feelings of exhilaration and euphoria, and offer a glimpse of the potential within our human spirit.
• Being chased or attacked. The sensation of being pursued in a dream evokes our primal instincts of fear and evasion. Psychologically, these dreams may symbolize avoidance of confronting unresolved conflicts or emotions. It may reflect a sense of being overwhelmed by external pressures or inner turmoil. Jung interpreted these dreams as a confrontation with our shadow selves—the darker, suppressed aspects of our personalities that demand acknowledgement.
• Teeth falling out. Although strange, dreams involving the loss of teeth are surprisingly common, and they often elicit feelings of unease and vulnerability. Psychologically, these dreams may symbolize a fear of aging, loss of vitality, or concerns about self-image . Alternatively, they, too, could signify a need for renewal and rebirth, shedding old habits or beliefs to make way for growth. Freud interpreted them to be reflections of sexual anxieties or castration fears, linking them to feelings of emasculation and powerlessness.
• Public nudity. Dreams of being naked in public can lead to profound feelings of vulnerability and exposure. Psychologically, these dreams could symbolize a fear of judgment, rejection, or social scrutiny. They may reflect insecurities about self-image or a desire to conceal perceived flaws and weaknesses. Jung interpreted nudity as a stripping of societal masks and pretenses, exposing the true self beneath the façade of social conformity .

From classical to contemporary psychology, the study of dreams offers a window into the depths of our subconscious. In our own personal quests for understanding, embracing the strangeness of our dreams allows us to explore the depths of our true selves. In our dream worlds, the unconscious speaks. By listening to it, we may uncover profound truths that lay beneath the surface of our waking lives.

A version of this article also appears on Forbes.com.

Mark Travers, Ph.D., is an American psychologist with degrees from Cornell University and the University of Colorado Boulder.

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What Do Your Dreams Mean? Sleep Experts Reveal Common Interpretations

Our weird and wacky dreams can be open to interpretation, but they might actually mean something. Here are common dream themes explained by sleep experts.

Turns out, that dream where you fall from the sky and jerk yourself awake is pretty common.

Given the extensive list of health reasons humans need rest, it's easy to understand why we close our eyes and go to sleep every night. But it's much more difficult to explain what happens as we drift off into dreamland. Why do we dream? How do we interpret those dreams, especially if they're bizarre or terrifying ?

Dreams are common. In fact, you have one to six dreams a night, the strongest ones happening during REM sleep . Nobody remembers all the dreams they have, and if you've ever woken from a particularly unsettling or offbeat dream, you may wonder why you're having it in the first place. You can start dissecting what your dreams mean with the help of three sleep experts we interviewed. 

Here's what to know about your dreams, what they mean and why you have them. 

What are dreams? 

Simply put, "Dreams are thoughts, images, sensations and sometimes sounds that occur during sleep," Alan Kuras , a licensed clinical social worker at Westmed Medical Group , tells CNET. 

There's no definitive evidence about what dreams consist of, but it's generally accepted that dreams represent a collection of thoughts, struggles, emotions, events, people, places and symbols that are relevant to the dreamer in some way. 

The most vivid dreams typically occur during REM sleep , though you can dream during other stages of sleep. 

Why do I dream? 

Dreams may serve multiple purposes, including memory formation. 

Kuras says there are many theories about the function of dreams. "They appear to assist in memory formation, integration, problem-solving and consolidation of ideas both about ourselves and the world," he says, adding that neuroscientists have discovered that dreams help with information processing and mood regulation, too.

While scientists know a great deal about what happens physiologically when people dream , there's still much to learn about what happens psychologically. For example, researchers know that people with post-traumatic stress disorder are likely to have nightmares . But people without PTSD have nightmares, too, so it can't be said that nightmares always accompany psychological conditions. 

One generally accepted concept is that  dreaming is a highly emotional process  because the amygdala (an emotional center in your brain) is one of the areas most active during dreams,  according to neuroimaging studies . 

Why can't I remember my dreams?

If you're one of those people who "doesn't dream," you probably just forget them. 

Part of this is biological, Kuras says, as neurotransmitters that form memories are less active during sleep. Dream forgetfulness also appears to be related to the level of electrical activity in the brain during dreams.

Additionally, it could have something to do with the content of your dreams. Early psychoanalytic theory suggested that difficult or traumatic information in dreams is suppressed, and the dreamer is less likely to retrieve or analyze it.

Dr. Meir Kryger, a sleep medicine doctor at Yale Medicine , tells CNET that most people remember their dreams when they're awakened in the middle of a dream or in the first few moments after a dream has ended. But the catch is that the memory only lasts for a short time. Unless you write it down or replay it in your head over and over, there's a good chance you'll forget the dream. It's more common to forget our dreams than it is to remember them, Kryger says. 

When you wake up also matters. Research has shown that people who wake up during REM sleep report more vivid, detailed dreams, whereas people who wake up during non-REM sleep report fewer dreams, no dreams or dreams of little significance. 

What does my dream mean? 

Dream meanings are mostly speculation, but what matters is how your dreams relate to your own life. 

Different cultures throughout history have ascribed meaning and importance to dreams, though there's little scientific evidence that dreams have particular meanings attached to them, Kuras says. "No one has yet determined with exactitude what dreams or the images in dreams mean. That dreams are significant indicators of one's subconscious mind is a basic assumption in various cultures, but in different ways."

Kryger says dreams are "mostly speculation in terms of specific meanings." He continues that there are two main trains of thought in the scientific community: One is that every part of a dream has a specific meaning, and the other is that dreams are entirely spontaneous and mean nothing.

The first train of thought can be attributed to Sigmund Freud , who is recognized as the first person to assign definitive meanings to dreams -- like that dreaming about a king and a queen actually means you're dreaming about your mother and father, Kryger says. 

Although dream psychoanalysis may have only begun in the last century or two, people have studied dreams for far longer: Aristotle wrote about dreams as early as 325 B.C., according to Kryger.

Lauri Quinn Loewenberg, a professional dream analyst, says the problem with arriving at proof across the board "is that dreams and their meanings are so very personal because they are based on the person's individual life experiences." 

Additionally, neuroscience tends to focus on the function of dreaming (like memory retention) rather than the "comparative analysis between the imagery in dreams and the content of the previous day, which is how I approach dream analysis," Loewenberg says. 

That said, certain dreams do have meanings attached to them, if for no reason other than holding significance for many people. Below, Kryger, Kuras and Loewenberg discuss the potential meanings of common dreams and symbols in dreams.

What does it mean when you dream about water, wind or fire? 

Dreaming about water, wind or fire may offer some insight into your emotions.

Though there's no concrete evidence that the elements have particular meanings (it's mostly speculation, Kryger says), some associations seem common. 

Water is thought to symbolize emotions, Loewenberg says, and different types of water can mimic different emotions. For instance, muddy water can represent sadness, tidal waves can represent overwhelm and clear water can represent emotional clarity. 

Fire most often equates to anger or distress, Loewenberg says, while wind can represent imminent changes or changes that you're currently going through. 

"As far as these being accepted meanings, all that truly matters is what fits for the dreamer," Loewenberg says. While many symbols have a general meaning that can fit most people and common situations, you have to account for your personal associations with symbols, she explains. 

What does it mean when you dream about death? 

It's actually very common to dream about death.

Kryger says it's very common to dream about death, particularly about the death of someone close to you emotionally. It's also common to interpret those types of dreams as communication from the dead, which isn't really a surprise: "Death has such a great impact on the living that it is often incorporated into dream content," he says. 

Loewenberg says dreaming about death can signify the end of something in real life, and that doesn't necessarily mean the end of a life. 

"To dream of your own death isn't a premonition but rather a reflection of how you are coming to realize that life as you now know it is coming to an end," she says, adding that it's not unusual to dream about death during things like moving, the process of quitting smoking or making a career change. 

According to Kuras, "This all depends on what these images mean to the dreamer in the context of their life and challenges. Dream work is very much the exploration of feelings and meaning for the dreamer and is somehow related to the 'work' of managing life and its challenges."

What does it mean when dreams are set at nighttime vs. daytime? 

Dreaming in dark settings, like this one, may indicate sadness or loneliness.

Like the elements, there's no scientific proof that darkness and light have set meanings, but many dreamers associate each with a particular feeling, Loewenberg says. For example, dreams that take place in the dark can represent uncertainty in real life -- such as if you are "in the dark" about something going on and need more information to make a decision. Darkness has also been associated with sadness or loneliness.

Dreams that take place in the daytime, on the other hand, may not mean anything for most people. But if you typically dream in dark settings and suddenly have dreams set in the daytime, it could signify that an issue was resolved or that you've come out of a period of sadness. 

Again, dream interpretation is almost entirely speculation, and what's important is how you relate your dreams to your own life. 

Why some dreams are common

Dreaming about flying is pretty common.

Have you ever dreamt that you were falling and jerked awake? If you've ever discussed said dream with other people, there's a good chance someone else chimed in saying, "I've had that dream, too!" Dreaming of falling seems to be pretty common, and it's something called an archetype, Loewnberg says. 

An archetype, by definition, is "a very typical example of a certain person or thing" (Oxford); when applied to dreams, an archetype is something that signifies " patterns of the psyche ." 

Other common dreams, which may or may not be archetypes depending on what's happening in your life at the time you have the dream, include: 

• Showing up late for something important
• Being chased by someone or something
• Dreams about sexual relations that shouldn't happen in real life (such as you or your partner engaging in relations with someone else)
• Encountering someone who has died
• Being paralyzed or unable to speak
• Being naked or embarrassed in front of a crowd

Loewenberg says these dreams are so common because they're connected to common behaviors, actions, thoughts and fears. For example, many (if not most) people worry about arriving late for something important, such as a work presentation or a plane flight. Likewise, many people may worry about their partner having an affair, which can show up in dreams. 

Having dreams where you appear naked or embarrassed in front of a crowd is often related to social anxiety, Loewenberg says, or worrying about how others perceive you. 

How to interpret your dreams

Some dreams are straight-up weird, and it's up to you to interpret them.

Since, as mentioned before, there's no solid body of evidence about the meanings of dreams, you have to interpret your dreams in ways that make sense to you. 

"The determination of what dreams convey are particular to the person and current situation," Kuras says, "so what the person is experiencing, what challenges they are facing, and what psychological developments are occurring will inform meaning in each case."

Dreaming is a thinking process, Loewnberg reiterates. "Our dreams, those strange little stories we experience every night while we sleep, are actually our subconscious thoughts," she says. "They are a continuation of our stream of consciousness from the day." 

But during sleep, instead of talking to yourself in words, you are talking to yourself in symbols, metaphors and emotions, Loewenberg says. The change in language happens because your brain works differently during REM sleep: Notably, the prefrontal cortex, or decision-making center of your brain, is less active or inactive, while the amygdala, the emotional center of your brain, is highly active. 

That's why dreams can be so frightening or frustrating and feature events that shouldn't or couldn't happen in real life. 

"In a nutshell," Loewenberg says, "dreams are a conversation with the self about the self, but on a much deeper, subconscious level."

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Life goals and their changes drive success

New study indicates if you can dream it, you can be it.

"Where is my life going?" "Who do I want to be?"

As future-thinkers, adolescents spend significant time contemplating these types of questions about their life goals. A new study from the University of Houston shows that as people grow from teenagers to young adults, they tend to change the importance they place on certain life goals, but one thing is certain: The existence of high prestige and education goals, as well as their positive development, can drive success.

"Adolescents who endorsed higher levels of prestige and education goals tended to have higher educational attainment, income, occupational creativity, occupational prestige and job complexity after 12 years," reports Rodica Damian, associate professor of psychology in the Journal of Personality and Social Psychology . The paper's first author, Andreea Sutu, is a former graduate student of Damian's. Also on the team are former UH assistant professor Kevin Hoff and Sif Einarsdóttir of the University of Iceland.

No prior studies have investigated associations between life goal development and educational or occupational outcomes.

Damian and colleagues found that goals fluctuate -- some dreams and goals of youth fall away while some, related to family (like being close to your relatives), relationships (like having good friendships or a romantic partner) and community (like being involved in your neighborhood or helping others) stay strong. These goals might become even more significant as people get older.

"Life goals are expected to change over time and these changes are expected to have consequences for future life outcomes, including occupational outcomes," said Damian. "By understanding how changes in life goals relate to educational and occupational outcomes (above and beyond adolescent levels), we show how changes within individuals may also predict desired educational and occupational attainment."

The study examined how life goals developed with age and how adolescent levels of goals, and their development through young adulthood, related to educational attainment and occupational outcomes in young adulthood. The study used two nationally representative samples of Icelandic youth followed longitudinally across 12 years from late adolescence to young adulthood.

"For educational attainment, the strongest effects were found for education goals. Both initial levels and slopes of education goals were positively associated with educational attainment in both samples," said Damian. "This indicates that adolescents with higher education goals, and those who showed a more positive change pattern in education goals, had higher educational attainment in young adulthood."

Education and prestige goals emerged as the most consistent predictors of later income and that changes in these goals across time were the most consistent predictors of later occupational prestige and complexity.

"Our work highlights the importance of better understanding sources of goal development in adolescence and young adulthood. Overall, our focus on life goal development, educational attainment and occupational outcomes informs theoretical and practical understanding about the importance of life goals for real-world outcomes," said Damian.

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• Andreea Sutu, Kevin A. Hoff, Chu Chu, Sif Einarsdóttir, James Rounds, Rodica Ioana Damian. Life goal development, educational attainment, and occupational outcomes: A 12-year, multisample longitudinal study. . Journal of Personality and Social Psychology , 2024; DOI: 10.1037/pspp0000499

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Why Do I Keep Dreaming About My Ex?

By Lisa Wong Macabasco

I’ve had a similar dream about an ex for years now: I pass them on the street, and they don’t acknowledge me. So why do I keep dreaming about my ex?

After long feeling ashamed to admit this, I was relieved to learn that not only is it completely normal for someone you cared about to make a cameo in your  dreams  but it’s also quite common. And that’s for a number of very good reasons, according to dream specialist  Deirdre Barrett , PhD, a Harvard psychology lecturer, past president of the International Association for the Study of Dreams, and author of the 2010 book  The Committee of Sleep ,  which explores how notable creative minds in art, music, film, science, literature, and other fields have used revelations in their dreams to inform their work.

Below find everything you need to know about why we dream about exes—and what to do about it.

Why do we dream?

Good luck getting dream researchers to agree about that, per Dr. Barrett. “Some more neurological types will say that we have rapid-eye-movement sleep, in which most dreams occur, for necessary biochemical things that the body needs to do, like replenishing certain sets of neurotransmitters that get depleted through waking, consolidating memory, and resetting temperature regulation,” she says. “Physiologic people like to say that dreams don’t have a function, that they’re a side effect of what our body needs to be doing physically during this time.”

But dreams also help us visualize more vividly and feel emotions more strongly than most of us are capable of when we’re awake, and they help us think outside the box, with the logic areas tamped down. For those reasons, we’re able to work through problems better in dreams than in waking hours. “Dreams are about all of our hopes and fears,” Dr. Barrett says. “Just about anything that we ever think about turns up in dream content. They’re about trying to problem solve things we’re facing in real life.”

Is it normal or common to dream about an ex?

Most people dream about their exes to some extent. “Dreaming about an ex just means they were a significant person in your past,” Dr. Barrett says. The people who you spent intense amounts of time with at any period of your life and who were important to you are likely to show up in your dreams, she notes, and that, of course, includes your exes, as well as parents and other family members or close friends. “Even if they’ve died or moved away or you’ve long lost touch with them, anybody you interacted with a lot will still be a significant person in some part of your unconscious for the rest of your life.”

Common dreams about exes—and possible readings

Each person’s dream about an ex is likely to have a meaning that’s entirely specific to them, involving both their feelings toward that ex and their life circumstances at the moment. Remember that meaning can vary widely from person to person—for example, a dog can mean safety and loyalty to one person or fear and anxiety to another. “For most dream elements, it’s a matter of  what is this to the dreamer ?” Dr. Barrett says. She also warns that the dreams may not be about that particular person, but more about issues one may have in the present.

Here are some broadly common dreams that can suggest certain underlying issues and unresolved feelings.

Maybe you were dumped by someone you were deeply in love with—a devastating experience, not to mention a significant ego blow, that may leave you wondering whether you did something wrong or perhaps weren’t “good enough” for them. Such an experience can lead to the following dreams:

By Elise Taylor

By Margaux Anbouba

By Alexis Bennett Parker

A) You get back together with the ex, or the ex apologizes and says they still love you: This is a wish-fulfillment dream based on the subconscious desire to feel good about yourself again.

B) You break into their home: This is related to the need to understand what happened and get inside their head and mindset.

If you’ve been in a relationship for a while and it’s become a bit too routine and comfortable, you may yearn for the passion of an earlier coupling—especially your first real love, which is imprinted on the psyche to represent love, desire, and passion. The following dreams may signify wanting to recapture those positive feelings in your waking life:

A) You have sex with them.

B) You get back together.

C) You search for them.

D) You care for children with them.

E) You see them out and about and are trying to get their attention.

F) You try to save them from some death or danger.

But dreams about exes may have nothing to do with them—or love, desire, or sex—specifically. Sometimes they represent who you were at that prior point in your life. If you dream about getting back together or having sex with an ex, it could simply mean that you long for who you were or what your life was like when you were with them.

Being cheated on or in an abusive relationship can leave a deep imprint on one’s psyche and lead to an ex appearing in dreams. Such a situation could indicate that something in your current life is causing you to experience similar feelings.

A) You dream you are being yelled at or cheated on: You may be experiencing some degree of similar feeling in your real life, or you may be still upset with yourself for being in that earlier relationship.

B) You dream about them leaving you: This may not necessarily be about the trauma of a breakup but could be about broader issues of rejection stemming from childhood, nonromantic relationships, or other abuse in one’s past.

When should you be concerned?

In general, you shouldn’t worry about dreaming about an ex. But if the dreams are consistently unpleasant and disturbing, Dr. Barrett advises seeing a therapist. “It may be an negative experience you haven’t completely resolved—it may also be that some things in your current life are stirring that up. Think about what in your waking life may be triggering this, even if it’s not as extreme as what the dream is depicting.”

At the other end of the spectrum, she says, “If you’re having extremely erotic, wonderful, safe, secure dreams about the ex over and over, I would tend to suggest therapy to work on what the dreams are about and what may be unresolved from the previous relationship.”

If you are in a relationship, should you feel guilty?

“You should never feel guilty about anything in a dream,” Dr. Barrett stresses. “Our unconscious just runs all over the place and has no effect on the waking real world. You’re not responsible for what you dream. It’s not doing something bad to your current partner, but it may be signaling that there’s something you want in life that you’re not getting from your current partner.” Potent emotional dreams, either positive or negative and especially involving repetitive themes, are worth paying attention to, she says. Consider asking yourself what they’re telling you about your waking life.

How can I stop dreaming about my ex?

The frequency with which you dream about an ex will probably decline as time passes and with the recency effect: “Somebody you broke up with 20 years ago will probably occasionally show up in your dreams, but not as often as somebody who you broke up with last year,” Dr. Barrett says. “Once you’re in a new good relationship, you will probably have fewer bad dreams about the past relationship.” Plus dream content simply changes over time as we focus on different issues.

Recurring, disturbing dreams about an ex may fade eventually (or, once you’re through another relationship, become about a more recent ex). “But they’re not going to go away without you both understanding something about why you’re dreaming them  and  making some change,” Dr. Barrett says. Deep-seated issues of rejection and jealousy are not likely to change without therapy work—or possibly through introspection and discussion with your current partner.

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ORIGINAL RESEARCH article

Investigating the influence of gamification on motivation and learning outcomes in online language learning.

• 1 Institute for Media and Communication, Department of Language, Literature and Media I, Faculty of Humanities, University of Hamburg, Hamburg, Hamburg, Germany
• 2 Guangzhou College of Commerce, Guangzhou, China
• 3 The University of Sydney, Darlington, New South Wales, Australia

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This study investigates the influence of gamification integration on language learning achievement among Chinese students while probing the mediating role of learners' motivation. Furthermore, it extends the boundaries of this investigation by exploring the moderating effect of digital literacy as a psychological predisposition. Data is collected through surveys from Chinese students enrolled in linguistic programs, employing a stratified random sampling technique and analyzed via SmartPLS SEM. The findings affirm the significant and positive impact of gamification integration on language learning achievement. The study introduces a moderated mediation model where learners' motivation serves as the mediator, and digital literacy acts as a moderator, further accentuating the significant impact of this integrated approach. This research advances our theoretical understanding of language learning, validating gamification's effectiveness as a motivational tool, and introduces digital literacy as a critical factor, providing deeper insights into personalized language learning experiences.

Keywords: Gamification Integration, Learners' motivation, Learning style preference, Language learning outcomes, online language learning

Received: 18 Sep 2023; Accepted: 19 Apr 2024.

Copyright: © 2024 Shen, Lai and Wang. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY) . The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Minjie Lai, Guangzhou College of Commerce, Guangzhou, China

Disclaimer: All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher.

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Chandra Reynolds, PhD

University of Colorado Boulder Muenzinger Psychology 345 UCB Boulder, CO 80309-0345

Office:   Muenzinger 

Education :  PhD, University of Southern California, 1994

Research Interests :

My research interests focus on life span development and aging, particularly the coaction and interplay of genes and environments on cognitive aging and the risk of Alzheimer's disease and related disorders (ADRD). I engage in longitudinal research, often of twins and adoptees, to examine how and why individuals differ in early life contexts and behavioral health pathways across time and their effects on cognitive functioning. Cognitive resilience in the face of genetic and environmental risks is a current direction of interest. In addition to participating in the international Interplay of Genes and Environment Across Multiple Studies (IGEMS) consortia, and the Vietnam Era Twin Study of Aging (VETSA), I am the contact PI of the Colorado Adoption/Twin Study of Lifespan behavioral development and cognitive aging (CATSLife).

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What about dreams ? State of the art and open questions

Serena scarpelli.

1 Department of Psychology, Sapienza University of Rome, Rome Italy

Valentina Alfonsi

Maurizio gorgoni.

2 Body and Action Lab, IRCCS Fondazione Santa Lucia, Rome Italy

Luigi De Gennaro

Associated data.

Several studies have tried to identify the neurobiological bases of dream experiences, nevertheless some questions are still at the centre of the debate. Here, we summarise the main open issues concerning the neuroscientific study of dreaming. After overcoming the rapid eye movement (REM) ‐ non‐REM (NREM) sleep dichotomy, investigations have focussed on the specific functional or structural brain features predicting dream experience. On the one hand, some results underlined that specific trait‐like factors are associated with higher dream recall frequency. On the other hand, the electrophysiological milieu preceding dream report upon awakening is a crucial state‐like factor influencing the subsequent recall. Furthermore, dreaming is strictly related to waking experiences. Based on the continuity hypothesis, some findings reveal that dreaming could be modulated through visual, olfactory, or somatosensory stimulations. Also, it should be considered that the indirect access to dreaming remains an intrinsic limitation. Recent findings have revealed a greater concordance between parasomnia‐like events and dream contents. This means that parasomnia episodes might be an expression of the ongoing mental sleep activity and could represent a viable direct access to dream experience. Finally, we provide a picture on nightmares and emphasise the possible role of oneiric activity in psychotherapy. Overall, further efforts in dream science are needed (a) to develop a uniform protocol to study dream experience, (b) to introduce and integrate advanced techniques to better understand whether dreaming can be manipulated, (c) to clarify the relationship between parasomnia events and dreaming, and (d) to determine the clinical valence of dreams.

1. INTRODUCTION

Dreams have been extensively studied from many points of view, focussing on different aspects of the phenomenon. Dreaming is a composite experience occurring during sleep that includes images, sensations, thoughts, emotions, apparent speech, and motor activity. The oneiric production is a form of mental sleep activity that appears strictly related to memory processes and cognitive elaboration (Wamsley & Stickgold,  2010 ; Mangiaruga et al., 2018). In this respect, some investigations have highlighted that dream features mirror the development of cognitive processes (Mangiaruga et al., 2018; Scarpell et al.,  2019a ).

Additionally, a growing number of studies have suggested that dream experience might be considered an expression of human wellbeing (Fränkl et al.,  2021 ; Scarpelli et al.,  2022 ) and has a pivotal role in emotional regulation, as suggested by some neurobiological findings (Nielsen & Lara‐Carrasco,  2007 ). For instance, dream recall and nightmare frequency increase when subjects are exposed to adverse and traumatic events (e.g., Hartmann & Brezler,  2008 ; Nielsen et al.,  2006 ; Sandman et al.,  2013 ; Tempesta et al.,  2013 ). Also, the qualitative characteristics of dream reports change in parallel with the emotional charge of waking experiences (Schredl,  2006 ; Scarpelli et al.,  2021 ).

It should be highlighted that psychoanalysis had primacy in dream research until the discovery of the rapid eye movement (REM) sleep stage (Aserinsky & Kleitman,  1953 ). The interpretation of oneiric contents was one of the main focusses of the Freudian theories positing that dreaming allows access to the unconscious functions of the mind in neurosis treatment (Freud,  1953 ). Aserinsky and Kleitman ( 1953 ) observed specific intervals with rapid and recurrent eye movement and bursts of alpha activity comparable to those that occur during wakefulness. The enthusiasm linked to the discovery of REM sleep considerably influenced dreaming research in several ways, and the neuroscientific study of dreaming is relatively recent. Several studies have attempted to identify the neurobiological bases of dream experience through a neuropsychological approach (Solms,  1997 , 2000 ), neuroimaging (Maquet et al.,  1996 ) and electrophysiological techniques (Marzano et al.,  2011 ; Siclari et al.,  2017 ).

Although several studies provide compelling evidence for the existence of specific brain mechanisms predicting dream recall (e.g., Siclari et al.,  2017 ), many questions are still at the centre of the debate.

The present paper summarises the main open issues concerning the neuroscientific study of dream experience. Specifically, the review offers an overview about (a) the question related to the REM‐non‐REM (NREM) sleep dichotomy, (b) the state–trait‐like problem, (c) the relationship between waking and dreaming state and the manipulation of dreaming, (d) the issue concerning the access to dream experience, (e) the role of nightmares, and (f) the debate on dreamwork in psychotherapy.

1.1. The REM‐NREM sleep dichotomy

A classical view of the neurobiological basis of the oneiric activity postulates the existence of a close relationship between dream experience and REM sleep (Hobson et al.,  2000 ; Nielsen,  2000 ). This hypothesis was based on early electroencephalographic (EEG) observations showing that >70% of individuals awakened during REM sleep reported dreams, while dream recall at the awakening from other sleep stages was rare (Aserinsky & Kleitman, 1955 ). According to this view, the wake‐like high‐frequency EEG pattern characterising REM sleep would represent the ideal electrophysiological scenario for the occurrence of dream experiences, while the slow‐frequency activity characterising NREM sleep would be associated with the absence of oneiric activity. However, using different criteria to collect dream reports, several studies found that successful recall of a conscious experience can be frequently observed also after NREM awakenings, and in a minority of cases no dream experience was reported after REM awakenings (Foulkes,  1962 ; Nielsen,  2000 ). Moreover, dream recall is still possible after lesions in brain regions involved in REM sleep generation, while the total disappearance of dream recall can be observed after focal forebrain lesions without an impact on REM sleep (Solms,  2000 ). Also, dream experience is preserved after pharmacological suppression of REM sleep (Landolt et al.,  2001 ; Oudiette et al.,  2012 ). Finally, dream recall has been recently associated with a similar electrophysiological response after REM and NREM sleep (D'Atri et al.,  2019 ; Siclari et al.,  2017 ). These results suggest that (a) dream and REM sleep are controlled by distinct brain mechanisms, (b) the postulate of a clear distinction between presence and absence of dreaming respectively in REM and NREM has not a solid support, and therefore (c) dreams can occur in any sleep stage.

A dichotomy between NREM and REM sleep has been also hypothesised for the qualitative aspects of dreams. Indeed, it has been proposed that REM and NREM sleep exhibit different kinds of mental activity. According to this view, REM sleep is characterised by an emotional, vivid, and bizarre “dream‐like” mentation (Antrobus,  1983 ; Casagrande et al.,  1996 ; Foulkes,  1967 ; Foulkes & Schmidt,  1983 ; Waterman et al.,  1993 ), while NREM mental activity would be “thought‐like”, with reduced emotional load, greater fragmentation, and contents more similar to waking thoughts (Foulkes,  1967 ; Rechtschaffen et al.,  1963 ). Nevertheless, the existence of a clear‐cut REM‐NREM dichotomy has been questioned also in this case based on several findings: (a) “dream‐like” reports have been observed also after NREM sleep (Monroe et al.,  1965 ; Solms,  2000 ; Zimmerman,  1970 ) and (b) the qualitative differences between REM and NREM dream reports disappear when their length is equated (Antrobus,  1983 ; Cavallero et al.,  1992 ; Foulkes & Schmidt,  1983 ).

In light of these observations, the assumption that the presence/absence and the phenomenological aspects of dream experiences strictly depend on the sleep stage per se is simplistic. It is worth noting that a precise definition of the time‐coupling between the sleep stages and the actual occurrence of dream experience is difficult, as the access to sleep mentation is possible only in an indirect way through dream reports after the awakening (see the paragraph “What about direct access to dream experience?”). At the same time, the occurrence of dream experiences in both REM and NREM sleep, two physiological stages characterised by distinct electrophysiological and neurotransmitters patterns, appears paradoxical. Such considerations raised the question of what mechanisms facilitate/inhibit the recall of a conscious experience at the awakening from different sleep stages, and what factors can explain intra‐ and inter‐individual variability in the phenomenology of the oneiric activity.

1.2. State‐ and trait‐like facets of dreams

Stable individual characteristics (trait‐like factors) can impact dreams, explaining inter‐individual variability. Sociodemographic factors like gender (Schredl & Reinhard,  2008 ; Settineri et al.,  2019 ) and age (Mangiaruga et al.,  2018 ; Scarpelli et al.,  2019a ) can predict dream recall. Interest in dreams (Bealulieu‐Prevost & Zadra,  2007 ), visual imagery abilities (Cory & Ormiston,  1975 ), personality dimensions like openness to experience, absorption, psychological boundaries (Beaulieu‐Prevost & Zadra, 2007), and predisposition to suppress negative emotions and thoughts (Malinowski,  2015 ) appear related to individual differences in the oneiric activity.

Crucially, neuroimaging studies provided evidence about the relationship between dream features and stable brain anatomical and functional characteristics. Qualitative facets of dreams have been associated with volumetric and structural measures of the amygdala‐hippocampus complex in healthy subjects (De Gennaro et al.,  2011 ) and amygdala volume, dorsomedial prefrontal cortical thickness, and dopaminergic activity in patients with Parkinson's disease (De Gennaro et al.,  2016 ). Moreover, compared to low dream recallers, high dream recallers showed (a) greater medial prefrontal cortex white‐matter density (Vallat et al.,  2018 ); (b) higher regional cerebral blood flow in the temporo‐parietal junction during wakefulness, Stage 3, and REM sleep and in medial prefrontal cortex during wakefulness and REM sleep (Eichenlaub et al.,  2014a ); (c) enhanced functional connectivity within the default mode network (DMN) and between areas of the DMN and memory‐related regions immediately after the awakening (Vallat et al.,  2020 ); and (d) larger event‐related potentials to distracting sounds even during active listening, arguing for enhanced bottom‐up processing of irrelevant sounds but also an enhanced recruitment of top‐down attention as suggested by larger contingent negative variation during target expectancy and P3b to target sounds (Ruby et al.,  2021 ). Taken together, these findings highlight that stable individual features of the brain structure and activation patterns can explain inter‐individual differences in dream experience.

Beyond the influence of trait‐like factors, a growing number of studies also point to the role of the physiological milieu associated with the oneiric experience (state‐like factors). In other words, the specific regional features of the physiological background contingent with dreaming would facilitate or prevent dream recall, potentially explaining intra‐individual differences in dream reports. This possibility has been investigated mainly by assessing the sleep EEG pattern preceding dream recall. In this way, several studies found that a successful dream recall was associated with greater frontal theta oscillations before the awakening from REM sleep (Marzano et al.,  2011 ; Scarpelli et al.,  2015 ; Scarpelli et al.,  2019b ) and reduced parieto‐occipital alpha activity before the awakening from NREM sleep (Esposito et al.,  2004 ; Marzano et al.,  2011 ). As theta and alpha oscillations are associated with memory processes during wakefulness (Hsieh & Ranganath,  2014 ), these results suggest that wakefulness and sleep share the same neurobiological mechanisms for the elaboration of episodic memories (see the next paragraph).

On the other hand, a growing number of within‐subject investigations (which allows overcoming the possible influence of stable trait‐like factors) show that a more desynchronised EEG pattern is associated with dream recall in both NREM and REM sleep (Siclari et al.,  2017 ; D'Atri et al.,  2019 ; Scarpelli et al.,  2017 ; Scarpelli et al.,  2020a ; but see Wong et al.,  2020 ). In particular, dream experience would be facilitated by a pattern of reduced slow‐wave activity (SWA), most steadily in posterior regions (Siclari et al.,  2017 , 2018 ). Interestingly, lucid dreams, phenomenon characterised by conscious awareness during the oneiric experience, appear associated with greater EEG gamma activity (Baird et al.,  2022 ; Voss et al.,  2009 ). Furthermore, a transcranial current stimulation delivered in a lower gamma range during REM sleep can affect the ongoing electrophysiological activity and increase self‐reflective awareness in dreams (Voss et al.,  2014 ). These observations are consistent with “activation” theoretical models (Antrobus,  1991 ; Hobson & McCarley,  1977 ; Koulack & Goodenough,  1976 ), which postulate that dream recall would be facilitated by a greater level of arousal during sleep, represented at an electrophysiological level by higher brain activation. Indeed, the frequency of dream recall increases in association with a sleep pattern characterised by greater sleep fragmentation (van Wyk et al.,  2019 ), faster spindles, especially in central and posterior cortical areas (Siclari et al.,  2018 ), intra‐sleep wakefulness (De Gennaro et al., 2010 ; Eichenlaub et al.,  2014b ; Vallat et al.,  2017 ), and sleep arousal (Polini et al.,  2017 ; Schredl,  2009 ). Furthermore, a night of recovery sleep after a period of prolonged wakefulness, usually characterised by reduced awakenings, almost totally abolished dream recall after the final morning awakening (De Gennaro et al., 2010 ). The SWA represents a marker of sleep intensity (Borbély & Achermann,  1999 ), likely subserving the fading of consciousness during sleep. Thus, the pattern of local SWA reduction in association with dreaming activity may represent the electrophysiological marker of the greater arousal level needed for a successful dream recall. Moreover, this evidence provides a reliable explanation for the apparently paradoxical occurrence of dreams in states of consciousness (i.e., REM and NREM sleep) characterised by drastically different EEG patterns.

Overall, these findings highlight the crucial role of the physiological state preceding dream recall. However, several questions remain open. First, the influence of circadian and homeostatic factors on the oneiric experience and its electrophysiological pattern is not clear (Chellappa et al.,  2011 ; D'Atri et al.,  2019 ; Scarpelli et al.,  2017 ; Scarpelli et al.,  2020a ). Moreover, the impact of the regional distribution of SWA on qualitative dream facets needs to be fully investigated, as empirical preliminary evidence has been provided only by Siclari et al. ( 2017 ). Finally, the possible interaction between state‐ and trait‐like factors should be carefully considered.

1.3. Continuity between waking and dream experience

The above‐mentioned “activation hypothesis” represents one of the main theoretical frameworks on dreaming, along with the so‐called “continuity hypothesis” (Domhoff,  2017 ; Schredl & Hofmann,  2003 ). In the early 1970s, Bell and Hall ( 1971 ) firstly proposed that waking experiences may have continuity in sleep. The formulation of the original concept has gone through several re‐interpretations and adjustments since then.

Early cognitively‐oriented studies focussed on the continuity between dream contents and waking events, personal concerns, thoughts, behaviours, and emotions, suggesting that waking‐life experiences are reflected into subsequent dreams (Nielsen & Powell,  1992 ; Schredl,  2006 ; Blagrove,  2011 ; Vallat et al.,  2017 ). Compelling evidence also showed the key role of the personal and emotional salience in mediating the preferential incorporation of waking‐life aspects during mental sleep activity (Malinowski & Horton,  2014 ).

Further, different time intervals between waking experiences and related dream contents could represent “day‐residue effect” or “dream‐lag effect” as a function of the elapsed period (i.e., 1–2 days and 5–7 days, respectively) (Eichenlaub et al.,  2017 ). Specifically, the delayed incorporation of waking life events (“dream‐lag effect”) was selectively observed during REM sleep and for personally significant events (Van Rijn et al.,  2015 ).

A complementary field of study posits the continuity between waking state and mental sleep activity from a neurophysiological perspective. Namely, a growing body of evidence suggests that brain mechanisms underlying cognitive and emotional functioning remain the same across different states of consciousness (e.g., Marzano et al.,  2011 ; Eichenalub et al., 2018).

The involvement of alpha (8–12 Hz) and theta (5–7 Hz) oscillations in memory‐related neural processes during wakefulness are well‐established, especially as regards episodic‐declarative memory (Klimesch,  1999 ). In particular, the increase in the frontal theta activity and the alpha power decrease during the encoding phase of episodic memories were found to play a pivotal role in the subsequent recall of stored information (Hsieh & Ranganath,  2014 ; Klimesch,  1999 ).

Over the last two decades, several studies were conducted under the assumption that dream encoding and recall could represent a peculiar form of episodic memory (Fosse et al.,  2003 ). As previously mentioned, a successful dream recall has been linked to higher frontal theta activity during REM sleep (Marzano et al.,  2011 ; Scarpelli et al.,  2015 ) and lower alpha activity over the temporo‐parietal region during NREM (Esposito et al.,  2004 ; Marzano et al.,  2011 ; Takeuchi et al.,  2003 ). Moreover, the topographical distribution of the above‐mentioned frequency bands resembles brain regions involved in encoding and retrieval mechanisms during wakefulness.

A large body of experimental studies have also shown the continuity between dreaming and emotional processing (for a review, see Scarpelli et al.,  2019c ). First of all, as described in the previous paragraph, neuroimaging studies showed the relationship between qualitative and quantitative stable aspects of dream experience and structural parameters of limbic areas (De Gennaro et al.,  2011 ). Consistently, subjects reporting higher levels of fear in their dreams showed a concomitant higher activation of the medial prefrontal cortex, responsible for reduced activation of the amygdala, insula, and midcingulate cortex both during sleep and wakefulness (Phelps et al.,  2004 ; Sterpenich et al.,  2020 ). Further, the main brain circuits involved in emotional processing during wake are highly activated during REM sleep, such as the limbic system (Nir & Tononi,  2010 ) and reward system (Perogamvros & Schwartz,  2012 ). Notably, a recent simultaneous EEG‐functional magnetic resonance imaging study demonstrated the privileged re‐emergence during sleep of patterns of brain activity associated with a recent rewarding (compared to a non‐rewarding) waking experience during sleep (Sterpenich et al.,  2021 ).

Starting from these findings, many researchers stated that dream activity might have a crucial role in processing emotional events experienced during wakefulness (see Scarpelli et al.,  2019c ). More in‐depth, the theta (Nishida et al.,  2009 ; Boyce et al.,  2016 ; Sopp et al.,  2018 ) and gamma activities (Van Der Helm et al.,  2011 ) were identified as the EEG markers of emotional memory processing. Selective sleep deprivation protocols provided experimental evidence about the lack of emotional memories consolidation in the absence of REM sleep stage (Spoormaker et al.,  2014 ; Wagner et al.,  2001 ), supporting the notion that dreaming represents the privileged scenario for the offline reprocessing of waking emotional stimuli.

Keeping in mind the unitary perspective across waking and sleep state, several investigations aimed to overcome the boundaries between different states of consciousness directly influencing sleep mentation by different kinds of sensory stimuli administered pre‐ or during sleep. Pre‐sleep stimulation methods have been used since the very beginning of dream research. The pioneering study by Dement and Wolpert ( 1958 ) showed the relation between the 24‐h fluid restriction in participants and their subsequent REM dream content. Sensory stimulation through pre‐sleep visual stimuli affected dream content by using stressful films (Goodenough et al.,  1965 ) or visual inverting prisms (Corsi‐Cabrera et al.,  1986 ).

Concerning sensory stimulation delivered during REM or NREM sleep stages, early studies described the incorporation of meaning verbal stimuli (Berger,  1963 ; Hoelscher et al.,  1981 ). Also, somatosensory stimulation (e.g., water on the skin, thermal stimulation, pressure cuff, electrical pulses) (Baldridge et al.,  1965 ; Dement & Wolpert,  1958 ; Koulack,  1969 ; Nielsen,  1993 ) or vestibular stimulation (Leslie & Ogilvie,  1996 ) were found to affect dream content. As expected, these types of stimulation increased vividness and bodily sensation in the dream contents.

Recent studies using olfactory stimulation during sleep showed the influence on the emotional content of dreams as a function of the hedonic characteristic of stimuli (Schredl et al.,  2009 ) and the reactivation of the odour‐associated images (Schredl et al.,  2014 ). The strong effect of olfactory stimulation on dream emotional aspects is interpreted in terms of direct connections to the limbic system (Smith & Shepherd,  2003 ).

In the last few years, a promising field of research explored the shared neural circuits between wake and sleep mentation by directly manipulating dream activity via transcranial electrical stimulation techniques. Some studies showed that interfering with cortical areas that are notably involved in a specific function during wakefulness influenced the dream content accordingly (Jakobson et al.,  2012 ; Noreika et al.,  2020 ).

Taken together, these results strengthen the hypothesis of shared mechanisms between the awake and sleeping brain from both psychological and neurobiological perspectives and through experimental manipulations. However, the intrinsic restraint due to the impossibility of directly investigating the dream content represents a common limitation of these studies.

1.4. What about direct access to dream experience?

The issue concerning dream access is definitively the most complex to address. Indeed, the real object of study in the abovementioned investigations (e.g., Chellappa et al.,  2011 ; Marzano et al.,  2011 ; Scarpelli et al.,  2015 , 2017 ; Scarpelli et al.,  2020a ; Scarpelli et al.,  2019b ; Siclari et al.,  2017 ) is “dream recall” and not the dream experience itself . In other words, dreaming is not directly observable, and researchers are able to obtain information about the oneiric activity just requiring a dream report to the individual when he is awake. Also, we have already discussed that detecting the exact moment in which the dreams are produced during sleep is very difficult.

From a methodological point of view, three approaches to collect dreaming are well‐known: (a) retrospective, (b) prospective, and (c) provoked awakenings with subsequent dream reports. While the retrospective method allows researchers to collect dreaming through interviews or questionnaires in large samples quickly, the prospective protocol (i.e., dream diaries; longitudinal dream report collection) is less prone to memory biases (Robert & Zadra,  2008 ). These two strategies allow classifying people in high and low recallers, helping to investigate the neurobiological trait‐like features of dreamers (e.g., Eichenlaub et al.,  2014b ; Eichenlaub et al.,  2014a ; Ruby et al.,  2021 ; van Wyk et al.,  2019 ). However, the most accurate approach is represented by the provoked awakenings associated with the polysomnography (PSG) of one or more sleep nights in a laboratory. Generally, participants are awakened to explore the presence of a dream report and to compare the recall and non‐recall condition (Scarpelli et al.,  2017 ; Scarpelli et al.,  2020a ; Siclari et al.,  2017 ) or the report's qualitative features (Scarpelli et al.,  2020b ), correlating them with the specific EEG patterns preceding the awakening. It is worth noting that the narration of dream contents could be influenced by many biases after awakenings, such as the experimental setting (Schredl,  2008 ), the physiological background of waking‐life and by individual variables, such as personality, cognitive functions, censure/omissions and socio‐cultural features (Nir & Tononi,  2010 ), making dream reports not always completely reliable.

How can we overcome this obstacle? In this regard, recent studies have suggested that viable access to mental sleep activity is represented by dream‐enacting behaviours (DEBs; Baltzan et al.,  2020 ). Any acting out of a dream during sleep characterised by motor, emotional or verbal components may be considered a direct observation of dream experience while the subject is asleep (Nielsen et al.,  2009 ). In this view, the study of parasomnias or parasomnia‐like events, i.e., REM behaviour disorder (RBD), sleep walking, nightmares, and sleep talking, may provide new insights about dreaming. Interestingly, some investigations highlighted a strong level of congruence between the body movements, verbal or emotional expressions during sleep and the subsequent components of dream recall (Arkin et al.,  1970 ; Leclair‐Visonneau et al.,  2010 ; Oudiette et al.,  2009 ; Rocha & Arnulf,  2020 ).

Assessing REMs in patients with RBD, Leclair‐Visonneau et al. ( 2010 ) found a concordance between limbs, head, and eye movements during the REM behaviour episode. The authors suggested that REMs may imitate the scanning of the dream scenario according to the so‐called “scanning hypothesis” (Arnulf,  2011 ; Leclair‐Visonneau et al.,  2010 ). Moreover, Oudiette et al. ( 2009 ) revealed that during sleepwalking or sleep terror episodes, subjects show complex motor behaviours strictly related to their oneiric scenes. The same group has demonstrated that sleepwalkers are able to replay the recently trained behaviour during the parasomnia episode, supporting the idea that dream enactment may have a pivotal role in memory processing during sleep (Oudiette et al.,  2011 ).

More recently, Rivera‐García et al. ( 2019 ) investigated the activation of facial muscles during REM sleep among healthy women. They considered facial expressions during sleep on a par with DEBs and an index of emotional dreams. Consistently, the previous literature shows that DEBs are more frequent during intense emotional dreams, such as nightmares (Nielsen et al., 2009 ). Indeed, the authors revealed that the activation of corrugator and zygomatic muscles are highly associated with dreams featured by negative affect (Rivera‐García et al. ( 2019 )).

Also, sleep talking could be considered an additional non‐pathological parasomnia‐like event related to dreaming (Alfonsi et al.,  2019 ; Mangiaruga et al., 2021). During sleep, the audible verbalisations may represent access to oneiric contents (Arkin et al.,  1970 ; Alfonsi et al.,  2019 ). In this regard, some studies showed different degrees of correspondence between sleep talking and dreaming (Arkin et al.,  1970 ; Rechtschaffen et al.,  1962 ). Arkin et al. ( 1970 ) reported different orders of concordance between sleep speech and later dream reports. Some authors investigated the presence of dialogical components within the dream reports proposing an overlapping between the neural mechanisms underlying linguistic production in dreams and those responsible for language during waking state (Shimizu & Inoue,  1986 ; Hong et al.,  1996 ; Siclari et al.,  2017 ). Specifically, Hong et al. ( 1996 ) found a reduction of the alpha activity focussed on Broca's and Wernicke's language regions, proportional to the amount of expressive and receptive language reported in dreams (Hong et al.,  1996 ; Shimizu & Inoue,  1986 ). In addition, Noreika et al. ( 2015 ) demonstrated a decrement in the theta and alpha activity in a single‐case study associated with linguistic hypnagogic hallucination. Consistently, a recent study revealed that similar EEG patterns predict intelligible verbalisations during sleep (Mangiaruga et al., 2022 ).

Overall, both findings in subjects suffering from parasomnias and those related to “benign” phenomena (e.g., facial expressions, sleep talking), suggest that parasomnia‐like episodes may open a new frontier in dream research making the oneiric production more accessible.

1.4.1. Nightmares

Nightmares are disturbing mental sleep activity characterised by negative emotions and often considered a clinical symptom causing significant distress. They are frequently associated with a high level of arousal and somatic manifestations that are capable to awake the dreamer from REM sleep. The repeated occurrence of this event is categorised as parasomnia, i.e., “nightmare disorder”, according to the Diagnostic and Statistical Manual of Mental Disorders, fifth edition (DSM‐5; American Psychiatric Association, 2013 ).

On the one hand, this disturbance is frequently related to post‐traumatic stress disorder (PTSD; Germain,  2013 ), but it could also be a reaction to stress conditions (Scarpelli et al.,  2022 ). On the other hand, also idiopathic nightmares, i.e., without a known cause, should be considered. For instance, this kind of mental sleep activity is quite common in children tending to disappear during adulthood, and it is more frequent among females (Nielsen & Levin,  2007 ).

From a neurobiological perspective, a recent investigation shows that the activation of the autonomic nervous system may be linked to nightmares (Paul et al.,  2019 ). Some studies revealed REM‐specific alterations in nightmare sufferers such as longer REM latency, increased skipping of early REM periods and cycle length, and more frequent REM periods (Nielsen et al.,  2010 ). Furthermore, some EEG findings highlighted the presence of slow frontal and central theta activity during REM sleep in a group of nightmare recallers (Marquis et al.,  2017 ). Further studies reported evidence for reduced slow‐wave sleep and greater intra‐sleep wakefulness (Simor et al.,  2012 ), increased alpha power during REM sleep, and higher levels of EEG desynchronisation in NREM sleep of students with frequent nightmares (Simor et al.,  2013 ). In other words, as already mentioned for dream recall, a higher autonomic and electrophysiological activation may provide the physiological background to the nightmare occurrence (Fisher et al.,  1970 ; Nielsen & Zadra,  2005 ). This is consistent with the self‐reported experience of greater emotional and physical activations during the nightmare occurrence.

Fear is the predominant emotion included in nightmares (Zadra et al.,  2006 ), suggesting that nightmares could be linked to fear‐dysfunction disturbances, i.e., phobias, generalised or social anxiety (Nielsen & Levin,  2007 ; Walker,  2010 ). In other words, nightmares could be related to the dysfunction in the hippocampal–amygdala prefrontal system that controls fear memory formation and extinction (Marquis et al.,  2017 ; Nielsen & Levin,  2007 ). Nevertheless, the functional role of nightmares is still debated. Considering the early theories of dream function emphasising roles for REM sleep and dreaming in promoting adaptation to stress, nightmares could be interpreted as a failure of this process (Wright & Koulack,  1987 ).

Along this vein, some authors proposed that a certain degree of awareness of our dream contents and the possibility of altering them may be beneficial for nightmares sufferers (Kellner et al.,  1992 ; Krakow et al.,  2001 ; Neidhardt et al.,  1992 ). In particular, compelling evidence highlighted that imagery rehearsal therapy (IRT) is very effective in reducing chronic nightmares within 6–12 weeks of therapy (Germain et al.,  2004 ; Kellner et al.,  1992 ; Krakow et al.,  2001 ; Neidhardt et al.,  1992 ). This technique consists of modifying the plot of the recurring nightmare during the wakefulness by an imaginal rehearsal of a new dream without disturbing items (Kellner et al.,  1992 ). The nightmare sufferers learn to change the nightmares scenes by creating a less unpleasant ending and including mastery elements in the new dream scenario (Germain et al.,  2004 ).

Interestingly, lucid dreaming induction could represent a useful intervention to reduce nightmares (Zadra & Pihl,  1997 ; Spoormaker & Van Den Bout,  2006 ; Rak et al.,  2015 ). It has been hypothesised that lucid dreaming could be a sort of coping strategy to face unpleasant stimuli during a dream experience (Schiappa et al.,  2018 ). Actually, lucid dream therapy is a cognitive technique that allows patients to learn to be aware of and modify their mental sleep activity during their nightmares through daily exercises (Spoormaker & Van Den Bout,  2006 ; Zadra & Pihl,  1997 ).

More recently, eye movement desensitisation and reprocessing (EMDR; Shapiro,  1989 ) has been employed for nightmares treatment in PTSD. Starting from the view that nightmares are the manifestations of adverse events registered in a dysfunctional form, this technique aimed to promote the recall of distressing images while activating one type of bilateral sensory input (e.g., hand tapping or side‐to‐side eye movement). The protocol allows subjects to identify and reprocess the targeted disturbing memories and experiences in order to formulate insight and adaptive behaviour.

In conclusion, it should be underlined that studies on PSG abnormalities and specific macro‐ and micro‐structural features correlated to nightmares are still missing. Further, efficacy studies on nightmare treatment (i.e., IRT, lucid dream therapy, EMDR) are scarce and fragmentary. Future research should be conducted to fill this gap and explore the effectiveness of the above‐mentioned interventions for nightmare disorders.

1.4.2. What role for dreamwork in modern psychotherapy?

An interesting open issue concerns the possible usefulness of the oneiric experience as a tool in clinical practice, also in light of the neuroscientific knowledge on dreams.

Classically, Freud (1953) proposed two main functions of dreams: the expression of repressed infantile wishes and the protection of sleep. The antimoral nature of such wishes implies the need of a distortion through the dream censor to be acceptable, allowing their partial expression while protecting the continuity of sleep. Freud distinguished the manifest and the latent content of dream, the latter containing the true meaning of the dream. Free associations would represent the “royal road” to uncover the latent dream content, and the analyst provide his/her dream interpretation on the basis of the patient's dynamics.

The role of dream interpretation in modern psychoanalytic models has been significantly redefined compared to the initial Freudian conceptualisation (Pesant & Zadra,  2004 ). Crucially, several authors focussed their attention to the intrinsic validity of the manifest facets of dreams and their relationship with the diurnal experience. According to different approaches, the role of dream has been conceptualised in terms of reorganisation of the experience (Fosshage,  2002 ), adaptation to reality (Gazzillo et al.,  2020 ), and co‐construction of the intersubjective reality (Jiménez,  2012 ).

Although several authors underline a “marginalisation” of dream in modern clinical psychological practice (Leonard & Dawson,  2018 ), it is worth noting that dreams have become an object of study also in clinical paradigms different from the psychoanalytical models (Pesant & Zadra,  2004 ; Velotti & Zavattini,  2019 ). Among the others, the evolution of the debate about dreaming in the cognitivist framework (Rosner et al.,  2004 ) represents an interesting example of the redefinition of dreamwork in psychotherapy based on novel experimental data, theoretical models, and clinical observations. Beck ( 1971 ) proposed that dreams reflect the individual conception (and biases) about the self, the world, and the future, and may represent and indicator of changes in the emotional status. Nevertheless, the initial need to move away from the psychoanalytical framework and the pressure to adopt an empirically verifiable clinical model led to a common disuse of oneiric activity in cognitive‐behavioural psychotherapy. Dreams were mainly considered as psychologically meaningless epiphenomena of sleep, useless for the dreamer and in turn for the therapeutic process. More recently, the progress in the scientific understanding of dreams has led to the reintegration of dreams among the object of interest from different epistemological paradigms in the cognitivist framework. From a rationalist perspective, starting from the hypothesis that dreams are subjected to the same cognitive distortions that characterise the waking experience, it has been proposed that dreamwork can help to detect cognitive biases and maladaptive thought patterns (Barrett,  2002 ; Freeman & White,  2002 ; Hill,  1996 , 2003 ) and promote cognitive reconstructing. On the other hand, the constructivist paradigm moved the focus on the narrative facets of dreams and the co‐construction of meaning between patient and therapist (Bara,  2012 ; Rezzonico & Bani,  2015 ; Rosner et al.,  2004 ), with the aim to promote the emergence of relevant aspects of the personal meaning and increase the level of awareness of the patient.

The interest in the clinical use of dreams led to the development of different articulated models of dreamwork in psychotherapy, like the Description, Memory Sources, and Reformulation (DMR) model (Montangero,  2009 ) and the cognitive‐experiential model (Hill,  1996 , 2003 ). Overall, Eudell‐Simmons and Hilsenroth ( 2005 ) identify four main functions of dreams in psychotherapy: (a) facilitate the therapeutic process, (b) increase patient insight and self‐awareness, (c) provide clinical information relevant for the therapist, and (d) provide a measure of therapeutic change.

Clearly, a further research effort is needed to provide support for the objective and efficacy of dreamwork in psychotherapy. Nevertheless, the ongoing debate on this topic has led to several models of the clinical valence of dreams that appear consistent with experimental findings on oneiric activity, mainly moving from standardised symbolic interpretations of dreams to approaches based on the relationship of dreaming with individual experience and cognitive/emotional/behavioural functioning.

2. CONCLUSIONS

From the discovery of REM sleep to the present day, empirical investigations have considerably increased our understanding of neural mechanisms underlying dream recall.

Although compelling evidence converges in providing support to the so‐called activation hypothesis and continuity hypothesis, considerable efforts are still needed to fully understand the neurobiological bases of oneiric processes.

Overall, we believe that (a) some results are still heterogeneous due to the application of different protocols, so a more consistent approach is needed; (b) the use of advanced techniques such as high‐density EEG or source localisation methods should be encouraged to better understand the relationship between specific oscillations and dream features; (c) further studies on experimental manipulation of dreaming should be carried out, also considering the implementation of brain stimulation techniques to promote dream recall or its specific characteristics; and (d) DEBs could be used as a model to observe dream contents overcoming the problem regarding the correspondence between specific time/stage of sleep and dream production, offering new insights about the neural correlate of dreaming.

Lastly, it is worth noting that recent pandemic studies have “elected” dream activity (and nightmares) as a reliable index of our emotional and psychological health (Fränkl et al.,  2021 ; Scarpelli et al.,  2022 ). Considering this, we underline that a translational view is needed to systematically explore the potential role of neurobiological and experiential facets of dreaming in a clinical context.

AUTHOR CONTRIBUTIONS

All the authors contributed equally.

CONFLICT OF INTEREST

All authors report no conflict of interest.

ACKNOWLEDGEMENTS

Open Access Funding provided by Universita degli Studi di Roma La Sapienza within the CRUI‐CARE Agreement. [Correction added on 26 May 2022, after first online publication: CRUI funding statement has been added.]

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How the American middle class has changed in the past five decades

The middle class, once the economic stratum of a clear majority of American adults, has steadily contracted in the past five decades. The share of adults who live in middle-class households fell from 61% in 1971 to 50% in 2021, according to a new Pew Research Center analysis of government data.

From 2020: Are you in the American middle class? Find out with our income calculator

The shrinking of the middle class has been accompanied by an increase in the share of adults in the upper-income tier – from 14% in 1971 to 21% in 2021 – as well as an increase in the share who are in the lower-income tier, from 25% to 29%. These changes have occurred gradually, as the share of adults in the middle class decreased in each decade from 1971 to 2011, but then held steady through 2021.

The analysis below presents seven facts about how the economic status of the U.S. middle class and that of America’s major demographic groups have changed since 1971. A related analysis examines the impact of the coronavirus pandemic on the financial well-being of households in the lower-, middle- and upper-income tiers, with comparisons to the Great Recession era. (In the source data for both analyses, demographic figures refer to the 1971-2021 period, while income figures refer to the 1970-2020 period. Thus, the shares of adults in an income tier are based on their household incomes in the previous year.)

This report analyzes data from the Annual Social and Economic Supplements (ASEC) of the Current Population Survey (CPS) to study how the economic status of the American middle class has changed since 1971. It also examines the movement of demographic groups in and out of the American middle class and across lower- and upper-income tiers from 1971 to 2021.

The CPS is the U.S. government’s official source for monthly estimates of unemployment ; the ASEC, conducted in March each year, is the official source for its estimates of income and poverty . The COVID-19 outbreak has affected data collection efforts by the U.S. government in its surveys, limiting in-person data collection and affecting the response rate. It is possible that some measures of economic outcomes and how they vary across demographic groups are affected by these changes in data collection. This report makes use of updated weights released by the Census Bureau to correct for nonresponse in 2019, 2020 and 2021.

In this analysis, “middle-income” adults in 2021 are those with an annual household income that was two-thirds to double the national median income in 2020, after incomes have been adjusted for household size, or about $52,000 to $156,000 annually in 2020 dollars for a household of three. “Lower-income” adults have household incomes less than $52,000 and “upper-income” adults have household incomes greater than $156,000.

The income it takes to be middle income varies by household size, with smaller households requiring less to support the same lifestyle as larger households. The boundaries of the income tiers also vary across years with changes in the national median income. Read the methodology for more details.

The terms “middle income” and “middle class” are used interchangeably in this analysis for the sake of exposition. But being middle class can refer to more than just income, be it the level of education, the type of profession, economic security, home ownership, or one’s social and political values. Class also could simply be a matter of self-identification.

Household incomes have risen considerably since 1970, but those of middle-class households have not climbed nearly as much as those of upper-income households. The median income of middle-class households in 2020 was 50% greater than in 1970 ($90,131 vs. $59,934), as measured in 2020 dollars. These gains were realized slowly, but for the most part steadily, with the exception of the period from 2000 to 2010, the so-called “ lost decade ,” when incomes fell across the board.

The median income for lower-income households grew more slowly than that of middle-class households, increasing from $20,604 in 1970 to $29,963 in 2020, or 45%.

The rise in income from 1970 to 2020 was steepest for upper-income households. Their median income increased 69% during that timespan, from $130,008 to $219,572.

As a result of these changes, the gap in the incomes of upper-income and other households also increased. In 2020, the median income of upper-income households was 7.3 times that of lower-income households, up from 6.3 in 1970. The median income of upper-income households was 2.4 times that of middle-income households in 2020, up from 2.2 in 1970.

The share of aggregate U.S. household income held by the middle class has fallen steadily since 1970. The widening of the income gap and the shrinking of the middle class has led to a steady decrease in the share of U.S. aggregate income held by middle-class households. In 1970, adults in middle-income households accounted for 62% of aggregate income, a share that fell to 42% in 2020.

Meanwhile, the share of aggregate income accounted for by upper-income households has increased steadily, from 29% in 1970 to 50% in 2020. Part of this increase reflects the rising share of adults who are in the upper-income tier.

The share of U.S. aggregate income held by lower-income households edged down from 10% to 8% over these five decades, even though the proportion of adults living in lower-income households increased over this period.

Older Americans and Black adults made the greatest progress up the income ladder from 1971 to 2021. Among adults overall, the share who were in the upper-income tier increased from 14% in 1971 to 21% in 2021, or by 7 percentage points. Meanwhile, the share in the lower-income tier increased from 25% to 29%, or by 4 points. On balance, this represented a net gain of 3 percentage points in income status for all adults.

Those ages 65 and older made the most notable progress up the income ladder from 1971 to 2021. They increased their share in the upper-income tier while reducing their share in the lower-income tier, resulting in a net gain of 25 points. Progress among adults 65 and older was likely driven by an increase in labor force participation , rising educational levels and by the role of Social Security payments in reducing poverty.

Black adults, as well as married men and women, were also among the biggest gainers from 1971 to 2021, with net increases ranging from 12 to 14 percentage points.

On the other hand, not having at least a bachelor’s degree resulted in a notable degree of economic regression over this period. Adults with a high school diploma or less education, as well as those with some college experience but no degree, saw sizable increases in their shares in the lower-income tier in the past five decades. Although no single group of adults by education category moved up the income ladder from 1971 to 2021, adults overall realized gains by boosting their education levels . The share of adults 25 and older who had completed at least four years of college stood at 38% in 2021, compared with only 11% in 1971.

Progress up the income ladder for a demographic group does not necessarily signal its economic status in comparison with other groups at a given point in time. For example, in 2021, adults ages 65 and older and Black adults were still more likely than many other groups to be lower income, and less likely to be middle or upper income.

Married adults and those in multi-earner households made more progress up the income ladder from 1971 to 2021 than their immediate counterparts. Generally, partnered adults have better outcomes on a range of economic outcomes than the unpartnered. One reason is that marriage is increasingly linked to educational attainment , which bears fruit in terms of higher incomes.

Married men and women were distributed across the income tiers identically to each other in both 1971 and 2021. Both groups nearly doubled their shares in the upper-income tier in the past five decades, from 14% in 1971 to 27% in 2021. And neither group experienced an increase in the share in the lower-income tier.

Unmarried men and women were much more likely than their married counterparts to be in the lower-income tier in 2021. And unmarried men, in particular, experienced a sizable increase in their share in the lower-income tier from 1971 t0 2021 and a similarly large decrease in their share in the middle-income tier. Nonetheless, unmarried men are less likely than unmarried women to be lower income and more likely to be middle income.

Adults in households with more than one earner fare much better economically than adults in households with only one earner. In 2021, some 20% of adults in multi-earner households were in the lower-income tier, compared with 53% of adults in single-earner households. Also, adults in multi-earner households were more than twice as likely as adults in single-earner households to be in the upper-income tier in 2021. In the long haul, adults in single-earner households are among the groups who slid down the income ladder the most from 1971 to 2021.

Despite progress, Black and Hispanic adults trail behind other groups in their economic status. Although Black adults made some of the biggest strides up the income tiers from 1971 to 2021, they, along with Hispanic adults, are more likely to be in the lower-income tier than are White or Asian adults. About 40% of both Black and Hispanic adults were lower income in 2021, compared with 24% of White adults and 22% of Asian adults.

Black adults are the only major racial and ethnic group that did not experience a decrease in its middle-class share, which stood at 47% in 2021, about the same as in 1971. White adults are the only group in which more than half (52%) lived in middle-class households in 2021, albeit after declining from 63% in 1971. At the top end, only about one-in-ten Black and Hispanic adults were upper income in 2021, compared with one-in-four or more White and Asian adults.

The relative economic status of men and women has changed little from 1971 to 2021. Both experienced similar percentage point increases in the shares in the lower- and upper-income tiers, and both saw double-digit decreases in the shares who are middle class. Women remained more likely than men to live in lower-income households in 2021 (31% vs. 26%).

Adults 65 and older continue to lag economically, despite decades of progress. The share of adults ages 65 and older in the lower-income tier fell from 54% in 1971 to 37% in 2021. Their share in the middle class rose from 39% to 47% and their share in the upper-income tier increased from 7% to 16%. However, adults 65 and older are the only age group in which more than one-in-three adults are in lower-income households, and they are much less likely than adults ages 30 to 44 – as well as those ages 45 to 64 – to be in the upper-income tier.

All other age groups experienced an increase in the shares who are lower income from 1971 to 2021, as well as a decrease in the shares who are middle income. But they also saw increases in the shares who are upper income. Among adults ages 30 to 44, for instance, the share in upper-income households almost doubled, from 12% in 1971 to 21% in 2021.

There is a sizable and growing income gap between adults with a bachelor’s degree and those with lower levels of education. In 2021, about four-in-ten adults with at least a bachelor’s degree (39%) were in the upper-income tier, compared with 16% or less among those without a bachelor’s degree. The share of adults in the upper-income tier with at least a bachelor’s degree edged up from 1971 to 2021, while the share without a bachelor’s degree either edged down or held constant.

About half or a little more of adults with either some college education or a high school diploma only were in the middle class in 2021. But these two groups, along with those with less than a high school education, experienced notable drops in their middle class shares from 1971 to 2021 – and notable increases in the shares in the lower-income tier. In 2021, about four-in-ten adults with only a high school diploma or its equivalent (39%) were in the lower-income tier, about double the share in 1971.

Note: Here is the methodology for this analysis.

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