3 scientific perspectives on why we dream
What's in a dream, after all?
Dreaming might be one of the key sleep characteristics that we know the least about, but that certainly isn’t for lack of interest in the subject.
Our earliest records of dream interpretation date all the way back to ancient Mesopotamia, Egypt, and Rome, where dreams were held in high-esteem as sacred messages from a higher power. Not only were dream-books used as a popular means of unravelling the meaning of a dream, but dream interpretation was also an honoured profession (1).
While our modern conceptualization of dreams may differ slightly from our ancestors, much of the science behind our dreams still remains unknown.
Dreams are pretty remarkable when you think about them, after all:
Our brain, disconnected from our external environment in its subconscious state, has the ability to generate entire worlds that we can take with us into our conscious experience. Often, some dream experiences are powerful enough for us to recall and reflect on for days, months, and even years to come!
As a result, however, the study of dreams is a formidable challenge.
Unlike typical scientific experiments, dreams can’t easily be manipulated, and - even if they could - researchers can only access them via participants' self-reports of the experience, and never direct observation.
So, while we haven’t quite figured out exactly why and how dreams work in the brain, there are a handful of established theories:
- Dreams are a by-product of our long-term memory storage processes.
- Dreams are an evolutionary mechanism to help us process our inner fears and emotions, making us more likely to survive and thrive in future situations.
- Dreams are our brain's way of introducing random variables in order to keep our neural connections flexible and avoid “overfitting.”
scientific perspective #1: dreams are a by-product of our long-term memory storage.
Over the course of a single minute, our brains can take up to 11 million bits of information in, whilst our conscious minds can only handle a small fraction of that amount.
So what happens in between receiving the information, and paying attention to it consciously?
Well, in order to cope with the high volumes of stimuli and environmental input we receive as we go about our day, the brain uses a number of automatic mechanisms to filter information and determine what to discard, and what to retain and share with our conscious minds. Naturally, everything that isn’t determined to be “important” information falls away; a process developed over thousands of years of evolution in order to help us survive (using a mental shortcut of two along the way)!
We also know that sleep plays a huge role in the consolidation of memory. During all stages of sleep, our brains work to sort through our short-term memory traces, organise them, and assess whether or not to commit them to our memory, long-term (2).
In this way, it’s theorised that dreaming is a by-product of the sorting and memory organisation that takes place during sleep. It’s not uncommon, after all, for our dreams to feature recent events, thoughts, people, and places from our day prior. This leads researchers to believe that the bits and pieces of information that we may experience recurrently within our dreams are a reflection of the sorting process, and perhaps an indication of the memories our brain wants us to later recall (3).
scientific perspective #2: dreams are an evolutionary mechanism for survival
In determining dreams to be a mere by-product of the process of sleep, researchers are effectively arguing that dreams don’t have a “real” or natural function of their own. This, however, is where others are inclined to disagree.
Because dreams can only be recalled consciously (yet they can only be experienced while we’re unconscious), some sleep experts suggest that we may be undermining the value of dreams - simply due to the fact that it’s hard to study them. As such, another popular conceptualisation of dreams is that they are actually far more organised and selective than we often give them credit for.
One evolutionary perspective on why we dream is that dreams help to equip us mentally to prepare for adverse and unfamiliar events by stimulating danger and/or forcing us to rehearse our fears (4).
More likely than not, each of us have experienced first-hand how unpleasant, embarrassing, or downright frightening our dreams can be. Well, this theory is supported by the idea that that’s no accident, you see. Among the findings of one study, researchers found that 66% of recurrent dream reports contained one or more personal threats to the dreamer - although less than 15% were actually plausible (5).
In other words, while the likelihood of turning up to our school’s talent show without any clothes on is (hopefully) not very high, our unconscious mind may present this exact situation as an uncomfortable threat while we dream…
Perhaps facing “scary” unrealistic events is the safest way for our brains to prepare us for the unknown. Similar to visualisation techniques, it may be that “seeing” the things we see in dreams, and getting the chance to act them out before they happen in real life is just one of the many factors that helped our ancestors stay alive.
How exactly it may be helpful for us to rehearse scenarios like this while we dream is the part that we still don’t fully understand. So, as always, there’s a need for further research.
scientific perspective #3: dreams are an exaptive mechanism for increased randomisation
More recently, even newer theories have emerged on dreaming, one of which is that while dreams may have started out as a purposeless by-product of memory organisation during sleep, they have since evolved to serve a unique function of their own.
The process of a trait shifting or gaining new function during evolution is a phenomenon referred to as “exaptation,” and is what would make dreaming, according to this next theory, an exaptive mechanism.
As consciousness researcher and neuroscientist Erik Hoel proposes, sleep is the perfect time for molecular housekeeping, i.e. sorting through all of the input and stimuli from the days prior and providing signals to the body and brain that help us differentiate the important stuff from the other “stuff.”
As the human brain has slowly but surely evolved to take in more and more input as our environments have become busier, we naturally become quicker at taking shortcuts and making assumptions about the world.
While for the most part our assumptions are right (for example: the traffic light changes amber and then green after it turns red, or it’s probably going to rain with those grey clouds above), it’s not a good thing for us to consider the world around us too predictable.
Similar to the inner algorithmic workings of the sofi brain, where data is analysed and carefully separated from any additional “noise,” our brains, too, require a degree of randomisation in order to function at their best.
“The point of dreams is the dreams themselves, since they provide departures away from the statistically-biased input of an animal’s daily life, which can therefore increase performance,” he says. “It may seem paradoxical, but a dream of flying may actually help you keep your balance running.” - Erik Hoel.
Hoel goes on to explain that there is a disadvantage to becoming too assured of what we know, and this disadvantage is known as “overfitting.” In machine learning, like with the sofi brain, overfitting is defined as “the production of an analysis that corresponds too closely or exactly to a particular set of data, and that may therefore fail to fit to additional data or predict future observations reliably.”
In other words, it could be the strangeness and unpredictability of dreams that allows us to make better choices, and live better lives, in and of itself (6).
And if that’s not a good reason to get some extra zzz’s then we don’t know what is!
For more on the mysterious world of dreams, check out this incredible story on the active benefits of passiflora on sleep by our in-house Ethnobotanist, Dr. Michael Balick.
And, if you haven't yet, sign up at sofi.health/sleep to participate as a Pioneer and get the chance to trial our latest plant pod formulations, completely free.
- Hughes, J.D. Dream Interpretation in Ancient Civilizations. Dreaming 10, 7–18 (2000).
- Wamsley EJ, Stickgold R. Memory, Sleep and Dreaming: Experiencing Consolidation. Sleep Med Clin. 2011 Mar 1;6(1):97-108.
- Cipolli, C. (1995). Sleep, dreams and memory: an overview. Journal of sleep research, 4(1), 2-9.
- Revonsuo, A. (2000). The reinterpretation of dreams: An evolutionary hypothesis of the function of dreaming. Behavioral and brain sciences, 23(6), 877-901.
- Zadra, A., Desjardins, S., & Marcotte, E. (2006). Evolutionary function of dreams: A test of the threat simulation theory in recurrent dreams. Consciousness and Cognition, 15(2), 450-463.
- Hoel, E. (2021). The overfitted brain: Dreams evolved to assist generalization. Patterns, 2(5), 100244.
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