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The brain can get a lot done, and leave you a little smarter, when it sleeps (sciam.com)
34 points by peakok on Aug 3, 2008 | hide | past | web | favorite | 16 comments

Great article, this is the type of interesting stuff that keeps me coming back. The author suggests an interesting hypothesis in the end:

"Memory processing seems to be the only function of sleep that actually requires an organism to truly sleep--that is, to become unaware of its surroundings and stop processing incoming sensory signals. This unconscious cognition appears to demand the same brain resources used for processing incoming signals when awake. The brain, therefore, might have to shut off external inputs to get this job done. In contrast, although other functions such as immune system regulation might be more readily performed when an organism is inactive, there does not seem to be any reason why the organism would need to lose awareness. Thus, it may be these other functions that have been added to take advantage of the sleep that had already evolved for memory."

Is this really that surprising to people? Many of the solutions to the problems I think about during the day come to me right as I fall asleep.

It's always just been a given for me.

This isn't about the time "right as you fall asleep". If it were, it would fit just fine with various earlier theories of sleep: the ones that concluded that sleep was just an extreme form of rest, a chance to let all those overworked neurons cool down and heal, and that you could get most of the benefits of sleep by, say, meditating.

But the new data is beginning to home in on what sleep accomplishes. And, in fact, your brain is doing a lot of work while you sleep. If I were to indulge in some CS-freshman handwaving, I'd say that the sleeping brain is doing garbage collection, lossy compression, and search indexing and optimization.

Is that surprising? I'd say that the really surprising thing is that we've gone through life up to now without really having any data on what sleep is for. So the new theory that sleep is primarily about memory management is more gratifying than surprising. It's about time we figured this out!

I think it's surprising that we still can't figure out the purpose of an observable process that blows a third (or more) of our lives, yet somehow we've come to a definitive theory on how the entire universe came into existence.

I guess the more we know, the more we realize we don't know.

I know folks who work on neural imaging. Let me assure you that to call sleep "an observable process" is a big exaggeration. Stars are much easier to observe than the details of your brain at work. Indeed, the reactions which drive stars are easier to see, understand, and simulate than a single neuron is.

It's not the size or the distance -- it's the complexity. I'm not saying that astrophysics is easy, but it's a lot less complex than the brain. Your brain is the most complicated thing in the universe... as far as we know.

It is just a matter of what you mean by understanding a thing. There are different standards applied to brains and stars.

A lot of things that count as understanding in stars are just normal to know about brains - for example mass, density, mechanical properties, energy throughput, age.

That "Human brains are the most complex thing in the universe"-meme strikes me as human chauvinism.

While some of this stuff may not be surprising to creative people (in terms of their personal experience), it's exciting to see empirical research moving in this direction. Examples:

- The brain may be selectively rehearsing the more difficult aspects of a task [...] each subject was getting faster on those particular [details] at which he or she was worst

- Sleep was doing this work by using different parts of the brain than were used while learning the task

- Somehow the sleeping brain was solving this problem, without even knowing that there was a problem to solve.

Any insight into creative process, especially creative process that bypasses the habitual efforts of the conscious mind, is exciting to me.

Edit: these findings are also welcome in the light of a lot of people's efforts to get by on as little sleep as possible. There have been many posts and comments here, in fact, about taking that to an extreme (or wanting to). This research suggests that those efforts are mistaken if one's goal is to maximize productivity, and provide the beginnings of a model for understanding why.

These moments of clarity usually come to me while I'm in the restroom.

The three B's of creativity: bus, bath, bed

All of which, in a sense, are a Between (or a Break).

Piotr Wozniak (inventor of SuperMemory) wrote about this eight years ago: http://www.supermemo.com/articles/sleep.htm

Sometimes when you return to a problem after a rest, you find your unconscious mind has left an answer waiting for you.


Powernapping achieves much of the same (atleast for me). So if for some reason you are unable to take sleep, at least be sure to try and fit in a ~20min powernap. The benefits can be surprising.

I've experienced this effect numerous times. Sleep is a wonderful thing. One time in high school I was working on an advanced calculus problem for several hours before going to sleep. I woke up in the middle of the night to use the restroom and realized that suddenly I had the key insight needed to find the solution. The problem was to find the solution to \int_{0}^{\infty} t^{- \frac{1}{2}} e^{-t} dt.

If only this worked all the time. Perhaps I should read up on the Riemann Hypothesis and see what happens tonight.

Sometimes we need years of studies to (re)discover what our elders knew long ago. That's probably from where comes the proverb : Night is the mother of counsel.

Finally, I can have that useless lump of pinkish-grey jelly work for me!

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