Randall Munroe on dreaming

"Dreams, as we all know, are very queer things: some parts are presented with appalling vividness, with details worked up with the elaborate finish of jewellery, while others one gallops through, as it were, without noticing them at all, as, for instance, through space and time. Dreams seem to be spurred on not by reason but by desire, not by the head but by the heart, and yet what complicated tricks my reason has played sometimes in dreams, what utterly incomprehensible things happen to it!"

-Fyodor Dostoevsky, "The Dream of A Ridiculous Man"

Dreams: they're bizarre, powerful, mundane, emotional, sexual, frightening, elating, and devastating. What makes them range from the droll monotony of stuffing napkin holders to the gut-wrenching insanity of being stuck on an alien planet and riding a giant version your childhood pet hamster?  Scientists and laymen alike have puzzled over the mystery of dreams for centuries--why do we have them, and, more importantly what do they mean (if anything)? Psychoanalysis would have us believe that dreams are an access point to our unconscious and Id-driven desires, unleashed while executive control snoozes. On the other hand, researchers who study sleep and dreaming have proposed that dreams are just noise, a by-product of the firing of neural pathways as the brain runs nightly maintenance scripts. At the end of the day, we just don't know much.

However, we do know that just like all perceived experience, you have your unique brain to thank for the experience of dreaming. Though we may not know whether our dreams should be interpreted as meaningful in the psychoanalytic sense, they may tell us something about who we are as individuals. If you're like me, you meet people who seem to have nothing in common with you when it comes to dreaming: I remember dreams often, some claim to "never" recall them; I tend to dream in deeply emotional and floridly bizarre expansive story-scapes, but I have friends who report that all of their dreams could (more or less) take place in real life ("I was late for work and naked"; "I made play-doh soup for my cat!?"). We know that people's brains are systematically different from one another, and that such differences correspond with personality trait variance. It seems reasonable to imagine that if these neurobiological differences give rise to individual differences in our waking life tendencies, they should also create measureable differences in our dream worlds.

The keen scientific mind will recognize the basic problem of measuring individual differences in dreaming: How can you determine if the variation we care about happens at the level of dream experience as opposed to dream recall? As yet, there is no solution to this roadblock, and so we are restricted to examining the dreams of those who can recall them adequately (perhaps magnetic resonance mind reading will deliver us?). Researchers who investigate individual differences in dreaming have classically focused on three major aspects of dreaming: Dream Recall Frequency (DRF), Frequency of Dream Type (Lucid Dreams, Nightmares, etc.), and Dream Content (e.g. emotions, interpersonal interactions, waking life activities, etc.). A review by Blagrove & Pace-Schott (which I highly recommend) evaluated the consistency of associations between individual difference measures and dream experiences, concluding that most associations were tenuous at best. Some personality traits did seem to matter somewhat consistently-for example, trait neuroticism/anxiety predicts nightmare frequency, and traits related to Openness to Experience (including Absorption, Boundary Thinness, and Attitude Toward Dreams) are the most consistent predictors of Dream Recall Frequency. However, studies show that nightmares are just as likely to occur from state waking anxiety (not just trait), presumably even for individuals low in neuroticism. Similarly, a closer look at the research on Boundary Thinness and Openness suggests that the differences occur mainly at the level of retrospective memory, not at the level of recall per se (in other words, people who are more likely to think about their dreams in the first place remember them more easily down the road--not so surprising; Beaulieu-Prevost & Zadra 2007). The authors of the 2010 review conclude that psychometrically assessed personality constructs just don't have that much to do with dream recall and content.

At first, I found the virtual dearth of associations between personality and dream content both surprising and disappointing, until I found this tantalizing section of the review:

"Domhoff (1996) reviews evidence of trait-like aspects of dream content, with data from dreams collected in the laboratory, or at home over a period of weeks, or in personal dream diaries that an individual has kept, often over many years. He summarizes this work as showing 'amazing consistency' in dreaming of 'types of characters, social interactions, objects, and activities,' and with the dream content being 'relatively free of major changes in life circumstances.' He also provides considerable evidence for correspondences between dreams and waking life, such that there are differences between individuals (such as famous writers) in these dream characteristics, and differences between groups, such as cross-cultural or sex differences. This follows on from the work of Hall (1947), where judges were able to identify postulated waking-life conflicts of dream diarists, and Hall (1953), which showed from a sample of 10,000 dreams how they are the embodiment of the person's whole personality and daily problems. Dream content can even be predictive of future circumstances: Cartwright and Wood (1993) showed that masochistic dream content was predictive, in women undergoing divorce, of less improvement at follow-up and more need for emotional support. There is therefore evidence for connections between waking life and dream content."

In essence, it seems as if rather than being directly parallel to waking life personalities, the dream incarnation of your personality may have some measurable, seperable aspects in its own right. Of course, this is not to say that there are no intersections between your waking and dreaming proclivities--the paragraph above certainly suggests the contrary. However, I suggest that the very neurobiology of REM sleep (Rapid Eye Movement Sleep: the sleep phase during which the most dreaming occurs) should lead us to expect a Dream-Self rather different from the Waking Self: You are still You, but stripped down and refracted through a unique biological lens.

In comparison to slow wave sleep, brain activity during REM sleep is strikingly similar to waking electroencephalographic (EEG) recordings. In the visual cortices, limbic areas, and orbitofrontal cortex, EEG activity is virtually indistinguishable from consciousness--the amazing difference is that broad swaths of the bilateral parietal and frontal cortices (motor function and executive cognitive function), both of which are constantly alive with activity in waking and during slow wave sleep, are in a comparatively quiescent state during dreaming (see Figure below).

Active and quiescent brain regions during dreaming.

What does this mean for how your personality might be transformed in dreaming? In short, neurobiology tells us that during REM sleep, your emotional and visual circuits are blazing with activity, while your executive control networks snooze away placidly. (This absence of frontal activity probably accounts for why we only perceive the strangeness of our dreams upon waking--and perhaps why we cannot seem to escape, fight back, and so on.) During dreaming, your brain's metaphorical conductor, usually responsible for error monitoring, evaluation, and planning, is basically on a lunch break (fun fact: onset of lucid dreaming is marked by an increase in activity in the frontal lobes during REM sleep!). One of the most common experiences documented in dream reports is the frustrated memory of knowing there was a plan/goal in your dream saga, but never  being quite able to take any steps toward completing it! Since the very neurobiological substrates from which your dreaming experiences arise are missing a crucial and omnipresent filter through which passes all of waking behavior (the introspective, planful, & evaluative executive brain), the types of behaviors that make up the contents of psychometrically assessed waking traits may be biologically blocked from the dreamer's experience.

Thus, the neurobiology of dreaming points to a surprising parallel with core ideas of psychoanalysis: the virtual absence of self-monitoring in dreams, combined with the apparent trait-like aspects of their content, indicates a world in which our dreams represent an experience of our more uninhibited and unbridled concerns and emotions.  Understanding how trait-like aspects of dream content relate to waking personality and to the individual differences in the neurobiology of sleep may help us to unravel the scientific mysteries surrounding the function of dreaming and consciousness more broadly.

We have some work to do before we can say with any certainty exactly what that dream about performing the macarena wearing a banana suit while your weird coworker yells "CUMMERBUND!" says about who you are. We should work to refine and standardize methods for measuring and recording dream content, and we may one day uncover a more mechanistic account of individual differences in dreaming. For now, I believe the science indicates that it is interesting and worthwhile to observe themes and patterns that occur in the dreams you remember--they may be telling you something about yourself that would otherwise be filed away out of consciousness under the orderly waking tyranny of those impressive frontal cortices of yours.

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