“…To be Abstracted From the World”: The Function of Dreaming
Why do we dream? My interest in this question was prompted by a fellow student’s remark in class in one morning. Most of our physiological processes seem to have a function, she observed, but what about dreaming? While the conversation that followed was rich and informative (and I especially liked Paul’s story of dreams as providing a whole new range of experiences, and that dreaming offers us a means of “trying out ourselves” in different circumstances) I was curious to learn what other neuroscientists had to say on the subject.
Since childhood, my own dreams have been a source of both anxiety and pleasure, self-knowledge and confusion. I enjoy vivid dream recall (perhaps because I keep a dream journal), am sometimes able to lucid dream, and have been having a recurrent dream of being devoured by a Great White shark for more than twenty years now.  Interestingly, though I have been clean of hard drugs almost ten years, I still occasionally dream about using, and when this happens, I carry lingering and difficult to shake feelings of guilt with me throughout the day. Given that my dream life is so rich and so readily colors my waking “reality”, it is curious to me that I had never before questioned their function. Nonetheless, I have never doubted that they served a purpose, cognitively and psychologically (and perhaps even spiritually). And so I was genuinely astonished to read that some neuroscientists deny this notion.
Dr. G. William Domhoff, a professor of psychology at the University of California, Santa Cruz, drawing on the work of research psychologists David Foulkes and Calvin Hall, writes, “…all the famous theorists who talk about dreams claim that dreams do have one or another purpose (although the famous theorists disagree on just what those functions are), but the best current evidence suggests otherwise. Dreams probably serve no purpose!” Domhoff rejects both Freud’s and Jung’s theories of dreaming on the grounds that they have been refuted by modern dream research. Domhoff points out that Freud’s thesis that dreaming serves to safeguard sleep (that is, that dreams signal us to wake up in order to attend to physical needs, like hunger or elimination) was invalidated by the discovery of REM sleep  in 1953, which demonstrated that dreaming happens throughout the night, not just before we awaken. Further, Domhoff claims, Jung’s concept that dreaming helps the psyche to experience parts of itself that go mostly unused during waking life has been disproved by studies that show that dream content is usually in harmony with the dreamer’s waking personality and concerns. As we are in waking life, so we are in our dreams, Domhoff asserts .
Domhoff notices that many people have little recollection of their dreams, which he considers an argument against their serving a function. Additionally, he argues, people who are able to recall their dreams don’t seem to be any “better off” psychologically when evaluated by means of standard personality tests. Disagreeing with other dream researchers I’ve discovered, Dumhoff rejects the idea that dreaming helps us sort through the events of the day, assisting us in the unconscious process of “deciding” to conserve or divest ourselves of certain memories. Dumhoff describes dreams as “plausible and even mundane” “stories” that have little to do with waking life. He writes
We are thinking creatures because thinking is a valuable adaptation, but that doesn’t mean all forms of thinking have a function. Dreams at this point in the collective findings of dream researchers seem to be a ‘throw-away’ production, an off-hand story to while the night away. that judgment could be changed tomorrow by new and original studies by a new generation of young dream researchers, but right now the preponderance of the evidence weights against any physiological or psychological function for dreams and dreaming. 
Researchers at the University of Alberta, who studied the dreams of 470 psychology students, would disagree with this claim. In this study, students recorded their dreams for two weeks and appraised the extent to which they were consistent with the events of their lives; researchers then evaluated whether or not the dreams evinced “problem-solving activity”. They concluded that many events that people experience have an impact on their dreams, both immediately after and up until a week after the experience. Oftentimes, they discovered, dreams that occurred further in time from the original event displayed problem-solving, interpersonal communication and positive feelings. These “delayed incorporations” indicated to them that dreaming serves the purpose of helping people manage the problems of waking life. Dr. Don Kuiken, a psychologist at the University of Alberta writes, “This suggests an ongoing effort to resolve a problem in dreams during the week following the emergence if that problem. The dreams themselves are a kind of treatment. Something is going on there that at least touches resolutions that people come up with.” 
Dr. Antti Revonsuo, a researcher at the University of Turku in Finland, agrees that dreaming serves a function. His “threat simulation theory” posits the idea that negative dreams prepare us to more effectively handle potentially dangerous situations in waking life. Drawing upon dream research literature, Revonsuo has noticed that in most dreams “negative” features are more widespread than “positive” ones: “Negative emotions are more common than positive emotions and aggressive interactions are more common than friendly interactions.”  Further, he discovered that approximately 80% of people have dreams in which they are being threatened or pursued. Revonsuo’s theory proposes that recurrent dreams replicate terrifying incidents because dreaming helps us to identify potential life-threats and appropriate modes of responding to them. (Interestingly, in my own recurring shark dream, I oftentimes punch the shark in his monstrous plate-sized black eye, which I hear is one way of disabling of a shark in “real” life. In the dream, such punching yields no result, though I keep on doing in future dreams, sometimes even remembering that it hasn’t worked in previous dreams.) “Exactly because they are most dangerous and life-threatening, the dreaming brain constructs the simulations in order for us to be better prepared to face such situations should they ever occur in our real lives,” he states. 
Molecular biologist Dr. Francis Crick (who discovered the DNA molecule) and theoretical biologist Dr. Graeme Mitchison have developed a “reverse learning” notion of the function of dreaming. This theory holds that dreaming helps the brain to rid itself of unnecessary information-- information that might overtax it, leading, perhaps, to hallucinations and obsessions. Dr. Robert Stickgold, a professor of psychiatrtry at Harvard Medical School’s Center for Sleep and Cognition, agrees that dreaming serves an important cognitive function. Stickgold argues that dreaming “…helps extract the meaning of events by building associative networks with other memories” and is “…probably a high-level of version of this processing.”  Stickgold conducted experiments in which twenty-seven subjects intensively played the computer game Tetris for a period of three days, and recorded their dreams. By the second night of the experiment, more than 70% of the test subjects were reporting dreams of falling geometric Tetris pieces, which demonstrated to Stickgold that some dreams are prompted by a need to learn. And one needn’t remember his or her dreams in order for this to be effective: “The brain is tuning your memory circuits as you sleep, and remembering the imagery created during the process may be fun, may be instructive, but it is almost undoubtedly a freebie.”
While Crick and Mitchison’s “reverse learning” theory may seems antithetical to Stickgold’s theory that dreaming aids learning, philosopher Friedrich Nietzsche’s remarks on the interdependence of thinking and forgetting may offer us a means of wedding these seemingly disparate notions. Nietzsche held that forgetting was a necessary component of cognition, and that conceptualization itself demands a type of forgetting about particularity. In “On Truth and Lies in the Extra-Moral Sense” he writes, “Just as it is certain that one leaf is never totally the same as another. so it is certain that the concept of a leaf is formed by arbitrarily discarding these individual differences and by forgetting the distinguishing aspects.” In the Genealogy of Morals, he makes an even stronger claim:
Forgetting is no mere vis inertiae as the superficial imagine; it is rather an active and in the strictest sense positive faculty of repression, that is responsible for the fact that what we experience and absorb enters our consciousness as little while we are digesting it (one might call the process “inpsychation”) as does the thousandfold process, involved in physical nourishment. To close the doors and windows of consciousness for a time; to remain undisturbed by the noise and struggle of our underworld of utility organs working with and against each other; a little quietness, a little tabula rasa of the consciousness, to make room for new things, above all for the nobler functions and functionaries, for regulation, foresight, premeditation (for our organism is an oligarchy)—that is the purpose of active forgetfulness, which is like a doorkeeper, a preserver of psychic order, repose and etiquette: so that it will be immediately obvious how there could be no happiness, no cheerfulness, no hope, no pride, no present, without forgetfulness. The man in whom this apparatus of repression is damaged and ceases to function properly may be compared (and even more than merely compared) with a dyspeptic—he cannot “have done” with anything. – from the Second Essay
If we agree, with Nietzsche, that cognition and memory (not to say psychological health) necessarily entail a sort of selective forgetting, we may make use of both Crick-Mitchison’s “reverse learning” and Stickgold’s “learning” accounts to understand some potential functions of dreaming. Because of the richness of my own dream life, and the lessons it has taught me about my hopes, fears and emotional composition, the idea the dreaming and learning are in some manner related appeals deeply to my own intuitive sense of their purpose and worth.
 “To sleep is to be abstracted from the world.” From the Jorge Luis Borges story, “Funes, the Memorious”, which imaginatively explores the Nietzschean notion of the interdependence of cognition and forgetting, an idea I explore later in the paper.
 My memoir of this dream, “What the Shark Taught Me” will be published in the upcoming Spring 2007 Nimbus, if you are interested in hearing about it.
 Rapid eye movement sleep, a stage in the sleep cycle which generally occurs every 90 minutes or so, when our “sleeping” brains are as active and aroused as when we are awake. Most dreaming occurs during REM sleep.
 “The ‘Purpose’ of Dreams”: http://www.dreamresearch.net/Library/purpose.html
 “Need a Solution? In Your Dreams” : http://www.sciencedaily.com/releases/2005/01/050111183922.htm
 “Field of Dreams” : http://www.guardian.co.uk/print/0,,4943014-111414,00.html
 “While You Were Sleeping” : http://www.time.com/time/printout/0,8816,160872,00.html