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We’ve all had strange dreams: as a kid I was not in the least frightened by the Count Chocula character while awake, but I suffered through many a nightmare about him, his fangs dripping chocolate blood as he stalked me, Bela Lugosi-style, through the eerily empty halls of my school. God knows why. Other dreams make even less sense: I’m packing for a trip when there’s a knock at the door. It’s Fedex. For some reason, supreme court nominee Sandra Sotomayor has overnighted me a kitten.
So why does the brain produce this narrative junk? We still don’t know why for certain, but the last few decades have produced a number of interesting evolutionary theories that move beyond old-hat Jungian archetypes or Freudian “wish fulfillment,” and Scientific American’s Jesse Bering recently laid out the Darwinian contenders.
Brain conditioning
If your brain went completely dark all night, the theory goes, it would begin to lose function just as rarely-used muscles will atrophy.
Several researchers, including the psychophysiologist Fred Snyder, argued that the adaptive purpose of dreaming may therefore be primarily to stimulate the brain or to keep it “in shape” during prolonged periods of inactivity. Later research offered support for this general idea. For example, specific categories of neurotransmitters were shown to be highly active during this period, while others seemingly “rested.”
In other words, as psychologist Steven Pinker puts it, “Dreaming might be a kind of screen saver in which it doesn’t really matter what the content is as long as certain parts of the brain are active.”
External vigilance
Most dreams are notably lacking in olfactory and auditory content, and one theory holds that that’s because if they were, the dreamer would be particularly susceptible to real-world threats like fire or noisy predators.
Being a “light sleeper” in relation to these other sensory domains had adaptive benefits, and since we’re in the dark anyway and our eyes are closed, there’s less of a risk in hallucinating in our secret visual worlds while our brains are being recharged.
Threat Simulation
This theory holds that dreams function as practice run-throughs for dangerous situations that may occur in the real world; they’re drills. (Of course, this theory doesn’t explain my kitten-in-the-mail dream; what was that preparing me for?)
“By giving rise to a full-scale hallucinatory world of subjective experience during sleep, the dream production mechanism provides an ideal and safe environment for such sustained practice by selecting threatening waking events and simulating them repeatedly in various combinations.” What we should see in contemporary dreams, argues Revonsuo, are “threat scripts” depicting primitive themes of danger that would likely have been relevant in the ancestral environment, such as being chased, falling and so on.
Dreaming as problem solving
According to Harvard University psychologist Deirdre Barrett, “sleeping on it” really works in terms of real-world problem solving, and may actually be the evolutionary purpose of dreaming (even if those dreams don’t always make sense to us.) In other words –
– dreamscapes provided our ancestors (and therefore us) with a sort of creative canvas for solving real-world problems. In support of this, Barrett describes the work of Stanford University psychologist William Dement, who in the early 1970s instructed hundreds of undergraduate students to work on a set of challenging brainteasers before bedtime, so that they’d fall asleep with the problems still on their mind.
What do you think?
Painting by Jamal Vrno.
You can follow my weird dreamlife via Twitter.
Comments (30)
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One of my psych classes in college espoused the “activation synthesis” theory. Like your “brain conditioning” description, your brain randomly fires neurons throughout the night. Then, as you begin to regain consciousness, your orderly mind tries to make a narrative out of all these pieces of information that have been triggered. Thus, the cat, Fed-Ex, and Supreme Court Nominee neurons in your brain fired, and your brain forced them into a (slightly) cohesive structure.
posted by terri on 6-30-2009 at 10:38 am
So you are saying that all those women who are out there dreaming about me are just trying to solve a problem?
Thanks for ruining my day.
posted by Witty Nickname on 6-30-2009 at 10:50 am
Endogenous Dimethyltryptamine produced by the Pineal gland could be why we dream…
posted by Kang on 6-30-2009 at 11:01 am
I support the “brain conditioning” theory.
posted by K on 6-30-2009 at 11:06 am
Dreaming is also a way to digest, categorize and store the information and experiences we took in that day.
posted by Bryan on 6-30-2009 at 11:27 am
“… dreams are notably lacking in olfactory and auditory content, and one theory holds that that’s because if they were, the dreamer would be …”
This sentence makes no sense. It should be “if they weren’t”.
posted by Jon. on 6-30-2009 at 12:02 pm
Jon is an A$$.
posted by Eat it Jon on 6-30-2009 at 12:39 pm
The brain, that mysterious overgrown cauliflower residing in the shadows of our skull is an evolutionary complexity that has outpaced itself. We can think with it, but we can’t fully comprehend it – like asking a typewriter to understand Mac OSX. Since the brain’s function is multifarious, it’s hard to believe that the purpose of dreams is unidimensional. All of the above theories likely yield some relevance in addition to others yet unknown.
For instance, there’s probably a degree of reflexology to the brain. Have you ever noticed when you’ve suddenly picked up a habit, like playing brickbreaker on your Blackberry 100 times a day, you’ll tend to dream about it, at least for the first few days of your addiction? Is it also possible that the overly or newly stimulated parts of our brains fire through out the night as a reflex – the actions of our days having built up like lactic acid after a getting-ready-for-spring-break work out?
Thanks for the article! I really enjoyed it.
Blog: http://1000awesomequestions.wordpress.com/
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posted by Sarah Grantham on 6-30-2009 at 12:39 pm
I wonder if we can draw off of animals to support/disprove these theories. My dog barks in her sleep; Pretty sure she is dreaming. I doubt she is problem solving; I love my doggie to death, but she isn’t the brightest star in the sky and doesn’t seem to have much reasoning ability. I would argue for the brain conditioning theory or threat simulation.
posted by David on 6-30-2009 at 12:41 pm
I believe that dreams are capable of foreshadowing future events…unfortunately we have not fully understood how to interpret them. Have you ever had whats called a “deja vu”? These are present events that one can remember already happening. The event can be traced back to a dream that one has already had of it.
posted by Chava on 6-30-2009 at 12:57 pm
I imagine the real explanation is somewhere between random activation and problem solving. Especially with a looser definition of “problem solving.”
You dream about something not because you have an upset/problem with it, but more because it made a big impression on you, and you’re metabolizing the image or the emotion associated with it. That’s what I think.
posted by Elizabeth W. on 6-30-2009 at 1:06 pm
I like the threat simulation idea; it’s like a dress rehearsal for life. Although I can’t for the life of me figure out why my most simulated threat as a child was escaping from a red house-shaped balloon, a Nazi, and an evil kite…
posted by erininhouston on 6-30-2009 at 1:18 pm
I found this article very interesting and I agree with Elizabeth W. I’ve heard dreams are the brain’s way of working through complex emotions you experienced during the day. They are processed while you sleep so you don’t have to spend you’re waking hours going them over and over again.
I’m 22 years old, and I’ve always dreamt very vividly as a child, but lately my dreams and nightmares are becoming really out of hand. They seem so real and upsetting that I usually need a good 10 minutes in the morning to sort out what really happened in my day to day life and what I just dreamed. Some of the imagery is so weird and bizarre that it follows me throughout the day as well. Somebody please explain this to me.
*When I got my braces at age 14, the first night I dreamt I ate a chain link fence. I think that one is pretty self-explanatory to anyone who’s ever had braces. :)
posted by LB on 6-30-2009 at 1:46 pm
I’ve always been interested in why a very few dreams tend to stick with you forever, like your cat dream, Ransom. I have two dreams from long ago that I will probably remember for the rest of my life, though they don’t really have special significance to me. Although one is about getting married and going to a submarine for my honeymoon, only to discover my wedding dress had turned into a canary yellow nun’s habit. Perhaps I was having boyfriend trouble at the time, so it stuck with me? Anywho, something I find odd.
And I’m of the random activation/problem solving school of thought.
posted by nutmeag on 6-30-2009 at 2:03 pm
Also, does anyone else have similar themed dreams? Like during high school I often dreamed I was shopping (even though I hated the mall and trying on clothes), and right now my boyfriend is appearing in all of my dreams. My mom has lots of dreams about WWII (which her father was in).
posted by nutmeag on 6-30-2009 at 2:05 pm
nutmeag, perhaps the mind frequently replays dreams that were first experienced at a fragile state or time of one’s life.
Maybe you do not have the dream terribly often, but when there is a lack in important information uptake on a particular day, or something happens that day that makes that dream and the situation it reminds you of come to the forefront of your unconsciousness…maybe you have that recurring dream.
The act of remembering it as a recurring dream may make it occur more often.
posted by iamchaossthought on 6-30-2009 at 2:17 pm
nutmeg–
I have a reoccuring dream of witnessing an airline crash. I’m never in the plane, it’s always in a different location and I’m always trying to get people out of the way for I am the only one who sees it coming. After it crashes, I always am running to help in whatever way I can.
It’s so real, I can feel the heat of debris as it flies past me. These dreams disturb me to no end, and they just come randomly. I’ve had about 5 or 6 over the past 2 years and it’s still so vivid in my mind. So yes, to answer your question, I have similar themed dreams. And they suck.
…Why couldn’t they be from Harlequin novels or something..?
posted by jenner on 6-30-2009 at 2:46 pm
How about repeating dreams? I used to have one as a child where a big fuzzy monster (like a cross between the purple people eater and cookie monster) lived in my basement. I would have to take my favorite blanket and fill it up with all the silverware and bring it down for it to eat…then I would start crying.
It used to be scary… though I had it until I was probably 14 or 15…by then it was kinda funny…
posted by kmel on 6-30-2009 at 2:47 pm
What about dreams that come true? I doubt the kitten one is going to happen in your case, but this happens to me a lot. It’s never been anything important. The last time this happened to me it had to do with meeting someone in a store in the mall. I ended up in a mall a short while after the dream and there this girl was. I even had her name right. For the record, I left out the little detail that I’m a psycho dreamer and knew her that way. I just don’t know how normal that would be…
posted by Kelsey on 6-30-2009 at 4:21 pm
Good comments about dogs dreaming. Scientist would be better suited I think to test kids and their dreams. With my own kids it might seem to be a “threat simulation”
But this group as a whole has probably got the better answer. Sara mentioned Brickbreaker and how she dreams about it while playing it a lot. The brain is OVER stimulated with some activity. Then in our dream state as Bryan mentioned we try to Categorize this information and those items that over stimulated us come to the forefront. Have multiple items. (Cat, Chief Justice) and you get a very weird dream. (Activation Syntesis). When I see my kids are over stimulated I remove them from the situation so they can sleep and so I can sleep.
posted by Harper, MD on 6-30-2009 at 4:29 pm
That stuff about dreams lacking ‘auditory’ and ‘olfactory’ content isn’t something I agree with. I’ve had plenty of dreams where all of my senses functioned. I could taste, smell, feel pain, and even think cognitively. I use to have a lot of trouble with them as a child because I wasn’t old enough to understand that even though they felt real, they weren’t.
I’ve also read about most dreams being in black and white. I’ve never had a black and white dream. They’ve always been in color and very vivid.
Or maybe I just have some odd sleep disorder (shrugs).
posted by KaeleaMajere on 6-30-2009 at 4:30 pm
I’ve always felt, with absolutely no facts to back this up, that dreaming was the minds way of ‘taking out the trash’. The ‘trash’ could be a logical problem, an anxiety, a desire. I guess that makes my theory a combination of them all and not a ‘real’ insight at all.
Riggs – As far as your dream goes, I would think that you want to get ‘a little p*$$y’ from the Court nominee and you absolutely, positively, need to have it overnight.
posted by TXCherokee on 6-30-2009 at 4:32 pm
I read another theory, which makes the most sense to me. In its stages of repair and recovery there’s a lot of random firing of neurons happening, and this causes the brain to experience little ’snippets’ of scenarios. To make sense of them, your brain fabricates a story around them, and in certain stages of sleep the same story or theme can continue on. I like this theory because I notice sometimes, just as I’m truly falling asleep, such ’snippets’ start popping up in my head. They’re incredibly brief – like one person saying one word or phrase, but I’m conscious of them as I start to fall asleep.
posted by Yams on 6-30-2009 at 4:50 pm
Yams, if you also feel a paralyzing sensation while you see these “snippets,” you might be experiencing sleep paralysis. This occurs when your brain knocks out your body before you are technically “asleep.” When this has happened to me, I have seen those snippets, too. Just quick flashes of images. I think proper dreams are your brain’s way of making sense of these images and possibly connecting them to each other. Met a sleep researcher at a party who said that’s the theory right now. Sleep paralysis could also explain some of those weird “alien abduction” stories.
posted by Shasta on 6-30-2009 at 5:54 pm
I’ve had some dreams involving sleep paralysis. (Think it happens when you’re really over-tired.) They are horrible.
I can remember being aware of the time, my surroundings, and all my senses – but unable to move or yell and “something” is coming to get me.
I’ve also had dreams where I kept tossing and turning in bed and looking at the clock – only to wake up and feel that I hadn’t slept at all.
posted by Nerak on 6-30-2009 at 7:27 pm
I think dreams work much in the same way extrasensory deprivation chambers work in causing hallucinations.The brain, not being able to make sense of nothingness, will essentially “make up” something to try to make sense of its surroundings. That’s why if, say your thirsty at night, you’ll dream of drinking water because the brain is grasping onto the strongest sensation and making the other senses follow suit with that one.
posted by PeteRepeat42 on 6-30-2009 at 8:08 pm
what about nightmares? i get them frequently seeing scary things like the end of the world ect. and i have only found one cure and that’s falling asleep to my greatest friend talking about anything and everything. its as if he makes them go away but how can i get rid of them without him?
posted by unwanted vision on 6-30-2009 at 8:25 pm
I have no idea why we dream, but I take advantage of them to fill my blog with mumbo-jumbo :)
Actually, I have a theory: dreams are to the brain as oxygen is to the lungs.
Just as air is the transport mechanism for oxygen, our experiences are the transport mechanism for the stuff of dreams (whatever “stuff” may be). Once inside our brains, this dream stuff provides the mental energy to do all the things suggested in the other comments.
Cheers,
Mitch
posted by Mitchell Allen on 6-30-2009 at 9:27 pm
can anyone explain why some people can’t dream at all and/or forget their dreams when they wake?
posted by marc on 7-1-2009 at 12:25 am
Is there any data, which shows that dreams have less olfactory and auditory content than in our waking lives? I imagine the only way to get this would be to wake up people in a sleep lab while they were dreaming and immediately ask them what they smelled or heard. Has this been done?
I have a feeling that people mostly report visually imagery in dreams because we are primarily visually-focused, so that is what we remember/deem important. The dreams of congenitally blind people are focused on auditory, rather than visual content, which makes sense these people are auditorially-focused when they are awake.
In addition, regarding auditory content, we most certainly remember conversations we have/things people say to us in our dreams since we communicate via spoken language. I would say that in many cases, the words spoken in a dream are more important to the dreamer than the scenery.
posted by Marcia on 7-1-2009 at 5:44 am