Summary The function of dreams is a question of long-standing scientific research. Simulation theories of dream function, which are based on the premise that dreams represent selective pressures from the evolutionary past and an improvement in fitness through altered states of consciousness, have not yet been tested in cross-cultural populations. that include small-scale collecting societies. Here, we analyze dream content with cross-cultural comparisons between the BaYaka (Rep. of the Congo) and Hadza (Tanzania) hunter-gatherer groups and populations from the Global North, to test the hypothesis that dreams in foraging groups fulfill a more effective emotional regulation function due to its strong social norms and high interpersonal support. Using a linear mixed-effects model, we analyzed 896 dreams of 234 people from these populations, recorded using dream diaries. The dream texts were processed into four psychosocial constructs using the Linguistic Inquiry and Word Count dictionary (LIWC-22). The BaYaka showed greater community-oriented dream content. Both the BaYaka and the Hadza exhibited higher threat content in their dreams, 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 showed the highest anxiety dream content. In conclusion , this study supports the notion that dreaming in non-clinical populations can effectively regulate emotions by linking potential threats to 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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Why do we dream?
A product of the neurophysiology of our brain, dreaming is a complex experience that can take on many emotional tones and simulate reality to varying degrees. As a result, there is still no clear answer to this question. A study led by the universities of Geneva (UNIGE) and Toronto, and the University Hospitals of Geneva (HUG), compared the dreams of two foraging communities, in Tanzania and the Democratic Republic of the Congo, with those of people living in Europe and North America. It showed that the first two groups produced more threatening, but also more cathartic and socially oriented, dreams than the Western groups. These results, published in Scientific Reports , show how strong the links are between the sociocultural environment and the function of dreams.
Dreaming is a hallucinatory experience common to all human beings. It occurs most frequently during the paradoxical phase of sleep, known as the rapid eye movement (REM) phase. However, it can occur at any stage of sleep. What are the physiological, emotional or cultural functions of dreams? Does it regulate our emotions? Does it prepare us to face a specific situation? Recent theories suggest that during "functional" sleep , the individual simulates more threatening and/or social situations, which would have an evolutionary advantage by promoting behavior adapted to real-life situations.
The outcome of dreams differs depending on the environment and population studied.
To test these theories, researchers from UNIGE and the University of Toronto compared the content of the dreams of the BaYaka in the Democratic Republic of the Congo and the Hadza in Tanzania, two communities whose way of life is close to that of our hunter-gatherer ancestors. , with that of different groups of individuals living in Europe and North America (Switzerland, Belgium, Canada), including healthy participants and patients with psychiatric disorders. For the BaYaka and Hadza, anthropologists at the University of Toronto collected dream narratives over a two-month period in the field. The data on dreams in Western groups comes from previous studies, published between 2014 and 2022.
’’We discovered that BaYaka and Hadza’s dreams are very dynamic. They often begin with a dangerous situation , in which life is threatened , but end up enacting a way to cope with this threat, unlike the scenarios of the Western groups that we observe. On the other hand, in clinical populations, such as patients suffering from nightmares or social anxiety, dreams are intense but do not contain cathartic emotional resolution . In these latter groups, the adaptive function of dreams seems to be deficient," explains Lampros Perogamvros, private teacher and group leader in the Departments of Psychiatry and Basic Neurosciences of the UNIGE Faculty of Medicine, and treating physician at HUG. Sleep Medicine, who led the study.
A mirror of the social fabric
Among the available responses of indigenous people to a threat in their dreams, the researchers found that those linked to social support were very common . This is the case, for example, when an indigenous person relates a dream in which he is hit by a buffalo in the middle of the forest, only to be rescued by a member of his community. Or when another dreams that he falls into a well and one of his friends helps him. These dreams contain their own emotional resolution.’
’’Between the BaYaka and Hadza, the social ties they have are, necessarily, very strong. Compared to the more individualistic societies of Europe and North America, daily life and the division of labor are often more egalitarian. It seems that this type of social connection, and dependence on community means that the best way to process the emotional content associated with the threat in your dreams is through the social relationships you have. In effect, these relationships are the emotional tools used to process life’s challenges," explains David Samson, associate professor of Evolutionary Anthropology at the University of Toronto, Mississauga, and first author of the study. Therefore, the research team suggests that there is a close connection between the function of dreams and the social norms and values of each specific society studied.
’’However, in this study it is difficult to deduce causal links between dreams and daytime functioning. Nor should we conclude that dreams in groups of Western individuals do not have an emotional function,’’ adds Lampros Perogamvros. In fact, in 2019, the same research team published a study showing that "bad dreams" in Westerners, that is, dreams with negative content that are not nightmares, are often simulations of our fears that prepare us for deal with them once they are awake. ’’There seems to be more than one type of ’functional’ dreams . The present study shows that there is a strong link between our sociocultural life and the function of dreams,’’ concludes the researcher.
Conclusion Here we support the idea that in non-clinical populations with real and perceived threats, dreams can process high levels of threat, but also be characterized by low anxiety and negative emotions. Our results indirectly suggest that dreams can effectively regulate emotions by linking potential dangers to 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. Furthermore, in at least one of these communities (the BaYaka), emotional catharsis is often achieved through strong social support. Ultimately, if dreaming prepares humans to face potential challenges and dangers in waking life, then our results are among the first to show these potential functions under evolutionarily relevant socioecological conditions. |
