
Sleep is Garbage Collection - soundsop
http://blogs.discovermagazine.com/80beats/2009/04/03/sleep-may-prepare-you-for-tomorrow-by-dissolving-todays-neural-connections/
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lucumo
If sleep is garbage collection, can I switch back to old malloc/free? So I can
do it more evenly over the day? :)

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amichail
Modern garbage collection is done more evenly:

[http://en.wikipedia.org/wiki/Garbage_collection_(computer_sc...](http://en.wikipedia.org/wiki/Garbage_collection_\(computer_science\)#Stop-
the-world_vs._incremental_vs._concurrent)

Perhaps the brain could do something similar.

~~~
davidbnewquist
In software, optimizing this type of garbage collection for low pauses usually
results in reduced application throughput. Evolution in general clearly does
not favor "low pause" sleep patterns.

However, there are anecdotes of rare people that subsist on "low pause"
sleeping. Allegedly, Thomas Edison had a 24 word day and frequently cat-
napped. Contrast that with Einstein who allegedly slept 10 hrs a night.

For modern garbage collection systems (e.g. the JVM), there is no single
setting that is best (or even acceptable) for all applications. The same is
probably true for sleep patterns.

~~~
amichail
_Evolution in general clearly does not favor "low pause" sleep patterns._

Evolution does not consider every possibility. And when it does consider one,
it doesn't necessary "implement" it well.

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davidbnewquist
Well, if the genes regulating sleep patterns are half as tedious as the gc
params for the 1.4.2 JVM, I wouldn't want to consider every possibility
either:P

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tsally
In yet another example, the overhead for automatic memory management is shown
to be prohibitive.

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jodrellblank
The dominant species on earth (humans) sleep, the generally believed to be
smartest animals sleep (humans, monkeys, dogs, various birds), the biggest
(elephants, giraffes), the hunters (big cats), the hunted, herbivores,
omnivores, the dominant type of fruit fly (in the article) sleeps. Even
creatures that would drown if they went unconcious (dolphins, whales) have a
kind of sleep.

What, exactly, has it prohibited?

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tsally
Because we're currently the smartest animal, you suggest we couldn't be better
if sleep were not required?

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jodrellblank
I do not suggest that. I merely ask you to support your jokey suggestion that
the overhead of sleep is prohibitive when it doesn't seem to have prohibited
... anything.

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tsally
If we didn't require sleep (and thus had 8 more hours each day we could work)
we could produce far more as a race. It's not like it's some crazy suggestion,
it's obviously true and unrealistic at the same time.

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ankhmoop
Beggars in Spain is an interesting treatment of that idea:

[http://www.amazon.com/Beggars-Spain-Trilogy-Nancy-
Kress/dp/0...](http://www.amazon.com/Beggars-Spain-Trilogy-Nancy-
Kress/dp/0380718774)

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giardini
Subjects taking modafinil can go without sleep for weeks. And studies show no
learning decrement in subjects taking modafinil. So is sleep truly required
for humans?

Memory in humans and other animals may so different from that of fruit flies
that drawing such a general conclusion as "Sleep is Garbage Collection." may
not be valid.

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anuraggoel
Sleep = GC and more available synapses = smarter*

So smarter people need less sleep?

Is the converse true?

* [http://www.telegraph.co.uk/scienceandtechnology/science/scie...](http://www.telegraph.co.uk/scienceandtechnology/science/sciencenews/3343912/Study-traces-the-evolution-of-the-human-brain.html)

~~~
lunchbox
Do you mean that smart people need less sleep to be able to perform a
particular task, or that smart people need less sleep to perform at their own
peak?

The above analogy leads more naturally to the first conclusion. Give a smart
person a cognitive task to perform, and gradually deprive him of sleep;
eventually, his performance will be reduced to the level of the average
person.

It's less clear how the second conclusion would hold -- that smart people are
_incrementally_ affected less by sleep loss than average people. In other
words, a priori, I don't think there's much reason to believe that a smart
person would be impaired less by losing an hour of sleep than an average
person would.

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anuraggoel
I wasn't aiming to go that deep, but to answer your question I meant the
ability to perform any given set of tasks.

Deriving the second conclusion needs a lot more data. Assuming there is no
analog for swapping to disk, the biggest missing piece is the rate of GC. Is
it the same for everyone? Additionally, is a given person's GC rate constant?
When I go without sleep for two days, I usually need more sleep than when I
missed sleeping for just a day. Does this mean there is more memory to
reclaim? Or that my GC rate has been impaired? Or both?

More interestingly, how do 'brain-building' foods and activities affect sleep
requirements?

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tdavis
I must have a very aggressive GC because my memory is all but worthless for
everything besides code.

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wingo
I have this too. I find it disturbing.

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kashif
I always thought so,I think it does some defragging too.

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almost
Nice one on the title soundsop! Great summary of what the article is saying in
terms that are familiar to us here :p

