1345: "Answers"

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1345: "Answers"

Postby najodleglejszy » Fri Mar 21, 2014 10:52 am UTC

Image

Alt-text: Stanford sleep researcher William Dement said that after 50 years of studying sleep, the only really solid explanation he knows for why we do it is 'because we get sleepy'.

can it be? my first XKCD comic thread submitted?
Last edited by najodleglejszy on Fri Mar 21, 2014 1:06 pm UTC, edited 1 time in total.

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Re: 1345: Answers

Postby dalcde » Fri Mar 21, 2014 10:56 am UTC

You didn't quote the title. Should be 1345: "Answers".

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Re: 1345: Answers

Postby rhomboidal » Fri Mar 21, 2014 11:05 am UTC

Philosophers stay up late wondering why we sleep. Philosophers with insomnia, why they can't.

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Re: 1345: Answers

Postby HerrVonMumpitz » Fri Mar 21, 2014 11:05 am UTC

And then you're getting so sleepy you can't sleep, but the alarm clock doesn't care.
Maybe shouldn't have been joking that I can sleep when I'm dead. So tired.
So much to do. So doing the morning run in the afternoon.

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Re: 1345: Answers

Postby JediMaster012 » Fri Mar 21, 2014 11:25 am UTC

Most people look at me strangely when I say I'm interested or have been interested in learning about sleep.

To me, it's always been absolutely mind boggling that so many people know so little about something we spend roughly 1/3 our life doing.

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Re: 1345: Answers

Postby cellocgw » Fri Mar 21, 2014 11:28 am UTC

I'm going to take a nap. Wake me when someone has the answer to why we sleep.
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Re: 1345: Answers

Postby Neil_Boekend » Fri Mar 21, 2014 11:28 am UTC

That's not a touche. It is more of an agreement.
The fact that we don't know why we sleep doesn't diminish our hunger to know why we sleep. Millions are spent in sleep research.
Hard questions take time to answer. That we still search for those answers is a testament to our hunger. Not a proof of its non-existance.
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Re: 1345: Answers

Postby cellocgw » Fri Mar 21, 2014 12:20 pm UTC

Oh, wait, we do know the answer:


To sleep; perchance to dream.
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Re: 1345: Answers

Postby thevicente » Fri Mar 21, 2014 12:41 pm UTC

"nobody knows why?" how is that?

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Re: 1345: Answers

Postby BrianK » Fri Mar 21, 2014 12:56 pm UTC

I hope I have enough posts to be able to do links...

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Re: 1345: Answers

Postby BrianK » Fri Mar 21, 2014 12:57 pm UTC

We sleep because garbage collection.

http://www.nih.gov/news/health/oct2013/ninds-17.htm

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Re: 1345: Answers

Postby cellocgw » Fri Mar 21, 2014 1:08 pm UTC

BrianK wrote:We sleep because garbage collection.

http://www.nih.gov/news/health/oct2013/ninds-17.htm


It's a raptor-or-egg problem, though. Maybe GC happens while we sleep because there's nothing better to do, but we sleep because it's dark out and our ancient ancestors didn't have television sets in their bedrooms. :)
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Re: 1345: Answers

Postby Mental Mouse » Fri Mar 21, 2014 1:15 pm UTC

Sometimes there aren't answers. It's not like we haven't been studying sleep since the Pharoahs were hiring dream-interpreters, but so far, what it looks like is more complicated than any one "because". Evolution tends to do that....

Nearly everything on the planet seems to have a diurnal cycle, that is a pattern of activity over the course of the day. That's natural, given that conditions change over the course of a day. Most animals will usually have at least some part of the day when it's less safe, useful, or comfortable to go roaming about, so might as well stay home (or someplace passibly safe). And if you're staying put for a while, you can save energy by going into a dormant state. Then, if you're already immobile, hey, it's a good time for healing and cleanup around the body. While you're at it, critters with more advanced brains can get some sorting done of their experiences and memories....

What we know as sleep is an accumulation of functions and "reasons" that has been collecting probably since animal life got started, or at least since it got out of the deep seas. I'd say that "don't know why" is more of a complaint that the universe isn't handing us a way to skip all that "useless" downtime!

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Re: 1345: "Answers"

Postby ucim » Fri Mar 21, 2014 1:29 pm UTC

I read recently (but don't have a link handy) that the brain actually shrinks during sleep - leaving more spaces between the cells. That allows toxins and such to drain more easily. In this state it's not unreasonable to suppose that there would be more "interference" with cell-to-cell signaling, and perhaps this is the cause of dreams.

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Re: 1345: "Answers"

Postby PsiSquared » Fri Mar 21, 2014 1:56 pm UTC

XKCD 1345 wrote:IWe all spend a third of our lives lying down with our eyes closed and nobody knows why


Most of us also spend another third of our lives in front of a screen that shows us mindless entertainment which atrophies our brains. Which, come to think of it, is pretty weird pastime for a species that defines itself with its curiosity for answer.

And I find the question of why so many people do that, to be a far greater mystery than why we sleep. At least when we sleep, we are doing something that benefits our brains and bodies. Not only the obvious (i.e. the fact that sleep is essential for our health) but also the side benefits we gain from all the creative processing the brain does while dreaming. We may not know the exact "why" or "how", but we do know that it's good for us.

Now, if you'll excuse me, I'm going to take nap. :)

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Re: 1345: "Answers"

Postby SlyReaper » Fri Mar 21, 2014 2:03 pm UTC

Isn't this a non sequitur? What does the existence of a gap in human knowledge have to do with humans wanting to fill those gaps?
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Re: 1345: "Answers"

Postby Morgan Wick » Fri Mar 21, 2014 2:33 pm UTC

Cueball is wrong, but more for the reasons PsiSquared suggests than what's presented. Just because we don't have the nitty-gritty details of the cause-and-effect chain that leads to us sleeping doesn't mean we don't know enough to have at least a basic explanation of sleep. (Now dreaming is another thing entirely.) On the other hand, there are way, way, way, way, way, way too many examples of people with no curiosity whatsoever (none of which I will give in order to avoid the inevitable flame war). I generally discount any explanation an intellectual gives for what separates us from the animals that amounts to a quality a cursory examination will show to be wanting in the vast majority of humans but that the intellectual does have (and whose presence in those humans that do have it has had a substantial impact on everyone else).

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Re: 1345: "Answers"

Postby rmsgrey » Fri Mar 21, 2014 3:38 pm UTC

My understanding is that the best theory is that animals sleep because the alternative to lying around conserving energy is to stay active and (on average) accumulate damage and burn resources, so creatures that take down-time when they don't need to tend to other needs will live longer, be more capable of raising offspring, and generally turn out fitter.

As others have said, once you get a routine downtime, it makes sense to shift various maintenance and upkeep tasks that can be performed then into that period rather than having them compete with more intensive activities, and you get things like dreaming and faster healing, and taking periodic downtime goes from being a regularly indulged convenience to a necessity, and continues to develop further complications and ramifications...

If nothing else, it's a neat picture, provides a plausible explanation, and is hard, if not impossible to test...

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Re: 1345: "Answers"

Postby imantodes » Fri Mar 21, 2014 4:14 pm UTC

That's not a touche. It is more of an agreement.
The fact that we don't know why we sleep doesn't diminish our hunger to know why we sleep. Millions are spent in sleep research.
Hard questions take time to answer. That we still search for those answers is a testament to our hunger. Not a proof of its non-existance.


Certainly such a large gap in our knowledge of humans undermines a claim that certain features are definitively human.

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Re: 1345: "Answers"

Postby speising » Fri Mar 21, 2014 5:33 pm UTC

a better reply would have been :"reality tv".

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Re: 1345: "Answers"

Postby hazyhomunculus » Fri Mar 21, 2014 5:44 pm UTC

brainsciencepodcast dot com/bsp/107-lewis

Latest news in sleep research: slow waves synchronously stimulate all nerves at approximately 1 Hz, disrupting their ability to perform normal activity; interstitial space expands during sleep allowing easier clearance of toxins (built-up misfolded proteins, misproduction rates increase progressively during waking hours); memories are all dimmed, to an extent important memories are selectively consolidated as information is transferred from the hippocampus to the neocortex, and the insignificant memories fade (this forgetfulness is proposed as an evolutionary adaptation).
And more!

There are definitely plenty of aspects left to discover, but we've at least begun to dig in. Once we understand it fully we'll perhaps be able to recover those lost hours. Of course this is lower-priority than most issues: we'll have completed the age vaccine by then, of course, but it will still be a significant improvement to be freed from our sleep obligations C:

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Re: 1345: "Answers"

Postby Andrew5DK » Fri Mar 21, 2014 6:30 pm UTC

I heard a podcast recently, stating the brain gets flushed, "much like a dishwasher":
Since this is my first post, I can't put a link to the study, but search University of Rochester Medical Center for news dated October 17, 2013 called "To Sleep, Perchance to Clean", lead author Maiken Nedergaard, M.D., D.M.Sc.
So now we do know why we sleep. It's fatal otherwise.

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Re: 1345: "Answers"

Postby yoyodu » Fri Mar 21, 2014 6:47 pm UTC

The reason is that the brain's cleaning system can only be used when the brain is inactive. The cleaning system removes waste products and toxins that can affect the brain.

Please see "Sleep Drives Metabolite Clearance from the Adult Brain", the scientific report.

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Re: 1345: Answers

Postby PinkShinyRose » Fri Mar 21, 2014 6:47 pm UTC

cellocgw wrote:Oh, wait, we do know the answer:


To sleep; perchance to dream.

So our entire sleep cycle is just to support REM sleep?
Mental Mouse wrote:Most animals will usually have at least some part of the day when it's less safe, useful, or comfortable to go roaming about, so might as well stay home (or someplace passibly safe).

So we shouldn't run around looking for creepers appearing?
PsiSquared wrote:
XKCD 1345 wrote:IWe all spend a third of our lives lying down with our eyes closed and nobody knows why


Most of us also spend another third of our lives in front of a screen that shows us mindless entertainment which atrophies our brains. Which, come to think of it, is pretty weird pastime for a species that defines itself with its curiosity for answer.

I think the positive reaction to the OTT is a bug, as are reactions to several other stimuli.

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Re: 1345: Answers

Postby da Doctah » Fri Mar 21, 2014 7:28 pm UTC

cellocgw wrote:I'm going to take a nap. Wake me when someone has the answer to why we sleep.

I'll ask my feral cat colony, if I can catch them during the two hours a day they're actually awake.

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Re: 1345: "Answers"

Postby BlitzGirl » Fri Mar 21, 2014 8:15 pm UTC

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Re: 1345: "Answers"

Postby SecondTalon » Fri Mar 21, 2014 8:19 pm UTC

Andrew5DK wrote:I heard a podcast recently, stating the brain gets flushed, "much like a dishwasher":
Since this is my first post, I can't put a link to the study, but search University of Rochester Medical Center for news dated October 17, 2013 called "To Sleep, Perchance to Clean", lead author Maiken Nedergaard, M.D., D.M.Sc.
So now we do know why we sleep. It's fatal otherwise.
That explains nothing. That's like saying "Getting stabbed is fatal because it lets the blood out." and ending right there. Why is blood necessary? Why is letting it out bad? We know that one.

Why is not sleeping fatal?


yoyodu wrote:The reason is that the brain's cleaning system can only be used when the brain is inactive. The cleaning system removes waste products and toxins that can affect the brain.

Please see "Sleep Drives Metabolite Clearance from the Adult Brain", the scientific report.
Explain dreaming and all the brain activity that happens during sleep then. Or why we lose consciousness rather than going catatonic.
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Re: 1345: "Answers"

Postby Wnderer » Fri Mar 21, 2014 8:44 pm UTC

Sleep is used by the matrix to maximize the number of inhabitants. By minimizing the amount of consciousness of its humans to the minimum required to maintain sanity and viability, the matrix makes the most efficient use of the energy produced by its human batteries. Dreams are a lower energy matrix that maximizes the amount of sleep a subject may endure. Research is underway to increase the amount of sleep and increase system efficiency. Humans in the 'wild' do not sleep.

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Re: 1345: "Answers"

Postby fr00t » Fri Mar 21, 2014 9:38 pm UTC

I don't think it makes much sense to talk about one particular reason for sleep, other than the general fact that evolution would have satisficed our sleeping habits given our ecological niche (being diurnal).

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Re: 1345: "Answers"

Postby LastDawnOfMan » Fri Mar 21, 2014 10:55 pm UTC

It seems to me that we're finally really reaching a good scientific consensus on sleep, and that it's probably getting to be late in the game to claim that we don't know why we sleep.

Previous posters have already pointed out two things:
1) our diurnal evolutionary design (homo-centric we are...the question of sleep applies to all sleeping animals, doesn't it?)
2) the clean-up process that is finally being documented. So far as we know, a two-part problem of
a) cleaning out waste products
b) converting memory molecules from shorter-term compounds to longer-term compounds

There are also many more minor processes that go on throughout the body, such as more rapid cell division and repair.

Anyone who studies medicine and biology eventually learns that biological systems are pretty adept at being very efficient with the situations and resources that are available. Or, that in other words, that there are differential evolutionary advantages to being efficient with those resources.

It seems that those creatures with features that helped them function better at a particular part of the day, (diurnal/nocturnal) were made safer and also able to conserve energy resources by becoming inactive at the times those features made them less functional. It is clearly efficient then to take advantage of such a time by using that inactive time to do the cleanup and memory rearrangement and other minor housekeeping tasks a biological system requires.

Simply putting these two things together answers the question pretty thoroughly on why we sleep, and so I have a hard time now seeing any mystery to it since the neural clean-up process has been documented.

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Re: 1345: "Answers"

Postby Korinthe » Fri Mar 21, 2014 10:57 pm UTC

Actually...scientists finally did find out a major reason why we need sleep, very recently.

During sleep certain cells in our brains, glial cells, which create channels around neurons that funnel cerebrospinal fluid throughout the brain to clear toxic proteins away from the neurons, start to pump the cerebrospinal fluid at dramatically increased rates, which clears said toxic proteins out at over twice the rate as an awake brain. Neurons also shrink during sleep, by ~60%, which increases the size of these channels. Apparently this process is very energy intensive for the glial cells, and the neurons are so thick it can overtax the glial cells when the neurons are at full size, which they immediately grow to upon waking. So this process only works while sleeping, and is very important to brain health.

It even seems to explain why larger animals need less sleep, and smaller ones more. Because the larger brains have more space for the glial cells to move the fluids (and thus toxic proteins), so can clear the brain more efficiently. Smaller brains, on the other hand, have less space and have to work harder to move the buildup of proteins through the smaller channels.

These protein buildups are also what appear to be the cause of Alzheimer's and similar degenerative brain diseases. This also helps explain why losing sleep makes your brain start to function worse and worse, as these proteins continue to build up to greater concentrations.

So it is a mechanism that actually has correlations with other puzzling aspects of brain activity.

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Re: 1345: "Answers"

Postby rmsgrey » Sat Mar 22, 2014 12:47 am UTC

fr00t wrote:I don't think it makes much sense to talk about one particular reason for sleep, other than the general fact that evolution would have satisficed our sleeping habits given our ecological niche (being diurnal).


It kinda depends on whether you're talking about why humans, specifically need sleep relatively frequently, and for such a large fraction of our lives - in which case there's not a simple answer, and the complex answer comes down to "because a whole bunch of stuff happens while you're asleep, which helps keep body and mind in working order" - or about why creatures sleep in general, in which case the answer comes down to "because there's a survival advantage in having periods of dormancy" (the other possible explanation for widely observed traits is that there are several viable alternatives, and our common ancestor happened to be the creature that took this option - in which case you'd expect to see some evidence of the other strategies having developed as well unless it turns out to be locked in way, way, way, way back up the evolutionary tree).

If you're talking about the particular survival advantage(s) sleep provides that enabled it to evolve in the first place, then it makes sense to talk about that as the reason(s) for sleep...

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Re: 1345: "Answers"

Postby The_Man » Sat Mar 22, 2014 5:25 am UTC

We all spend a third of our lives lying down with our eyes closed and nobody knows why


This is so wrong that I'm going to make my first post about it!

I consider myself to know more than the average person about sleep because I have extensively read about sleep; I suffer from a sleep disorder (idiopathic hypersomnia / narcolepsy without cataplexy). It causes me to sleep and feel tired far more than a healthy person.

Your sleep is actually divided into several phases which normally occur multiple times each night: light sleep, slow wave sleep (deep sleep), and REM sleep.

It is widely believed that slow wave sleep is the most important phase of sleep. During slow wave sleep, your brain waves are at their absolute slowest, blood flows to your muscles to recover from workout/injury, and your body produces testosterone and growth hormone. There is a prescription drug called "Xyrem" which increases slow wave sleep. The drug is prescribed to patients with narcolepsy to increase the quality of their sleep at night, helping them to stay awake during the day. Years ago, this drug was available over the counter and athletes used it as a performance enhancing drug. Come to think of it, it's probably the world's second most maligned drug after cannabis. Not only that, but experiments were done in which people would be momentarily disturbed each time their bodies tried to transition from light sleep to deep sleep. In those experiments, test subjects showed signs of fibromyalgia within a few days. Slow wave sleep is vital!

REM sleep, I don't know as much about, but it's widely believed that it has to do with memory consolidation.

Furthermore, it is said that without sleep, we die faster than without food, and I don't see anyone saying: "We put dead plants and animals in our mouths and no one knows why!"

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Re: 1345: Answers

Postby sotanaht » Sat Mar 22, 2014 7:54 am UTC

Neil_Boekend wrote:That's not a touche. It is more of an agreement.
The fact that we don't know why we sleep doesn't diminish our hunger to know why we sleep. Millions are spent in sleep research.
Hard questions take time to answer. That we still search for those answers is a testament to our hunger. Not a proof of its non-existance.


If humans were defined by their search for answers one would think that the answer to a question plaguing a third of all of our lives would get more than mere millions. Billions? Probably tens of trillions really.

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Re: 1345: Answers

Postby Neil_Boekend » Sat Mar 22, 2014 11:15 am UTC

sotanaht wrote:
Neil_Boekend wrote:That's not a touche. It is more of an agreement.
The fact that we don't know why we sleep doesn't diminish our hunger to know why we sleep. Millions are spent in sleep research.
Hard questions take time to answer. That we still search for those answers is a testament to our hunger. Not a proof of its non-existance.


If humans were defined by their search for answers one would think that the answer to a question plaguing a third of all of our lives would get more than mere millions. Billions? Probably tens of trillions really.

A. There are more questions to answer.
B. Cueball is wrong. Most people do not question, hence the popularity of religion. Most people are uncomfortable with not knowing. Some fill that with searching for the answers, most fill it with not questioning.
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Re: 1345: Answers

Postby Darekun » Sat Mar 22, 2014 10:53 pm UTC

BrianK wrote:We sleep because garbage collection.

http://www.nih.gov/news/health/oct2013/ninds-17.htm

Hunh, with that setup I thought it was going to be the neural net thing…

cellocgw wrote:It's a raptor-or-egg problem, though. Maybe GC happens while we sleep because there's nothing better to do, but we sleep because it's dark out and our ancient ancestors didn't have television sets in their bedrooms. :)

Well, there's two very different questions inside "why do we sleep"; there's why we started sleeping, and why sleeping is so important to keep doing. The first may easily have such prosaic answers… but brained species that must "work hard" in order to sleep, do so. Species that don't have the kind of downtime we have daily, and whose ancestors haven't for millions of years, still waste opportunity sleeping; dolphins use "differential sleep" because they require activity even while sleeping, and albatrosses may do the same thing; species with no reasonable circadian clock(think deep ocean) will nevertheless have some kind of clock for sleep, often with a bunch of unrelated downtime; etc. Most of the easy explanations break down when you consider other species with brains.

Personally, I'd bet on the neural net thing; damping weak connections to avoid the crazy can't be done while taking in data. (Basically, new data starts weak.) Of course, that would mean bad things for technological neural nets, so we may solve it some day :J

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Re: 1345: "Answers"

Postby PinkShinyRose » Sat Mar 22, 2014 11:42 pm UTC

Do animals need a ganglion to sleep? Do jellyfish sleep? Maybe it's just easier to detect in concentrated clusters of neurons.

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Re: 1345: "Answers"

Postby Mikeski » Sat Mar 22, 2014 11:59 pm UTC

PinkShinyRose wrote:Do animals need a ganglion to sleep? Do jellyfish sleep?

If so, do the teenage male ones dream about starring in anime?

Spoiler:
If you were expecting a hentai joke, then that's what this was.
If you weren't expecting a hentai joke, then I meant this show.

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Re: 1345: Answers

Postby addams » Sun Mar 23, 2014 5:16 am UTC

Darekun wrote:
BrianK wrote:We sleep because garbage collection.

http://www.nih.gov/news/health/oct2013/ninds-17.htm

Hunh, with that setup I thought it was going to be the neural net thing…

cellocgw wrote:It's a raptor-or-egg problem, though. Maybe GC happens while we sleep because there's nothing better to do, but we sleep because it's dark out and our ancient ancestors didn't have television sets in their bedrooms. :)

Well, there's two very different questions inside "why do we sleep"; there's why we started sleeping, and why sleeping is so important to keep doing. The first may easily have such prosaic answers… but brained species that must "work hard" in order to sleep, do so. Species that don't have the kind of downtime we have daily, and whose ancestors haven't for millions of years, still waste opportunity sleeping; dolphins use "differential sleep" because they require activity even while sleeping, and albatrosses may do the same thing; species with no reasonable circadian clock(think deep ocean) will nevertheless have some kind of clock for sleep, often with a bunch of unrelated downtime; etc. Most of the easy explanations break down when you consider other species with brains.

Personally, I'd bet on the neural net thing; damping weak connections to avoid the crazy can't be done while taking in data. (Basically, new data starts weak.) Of course, that would mean bad things for technological neural nets, so we may solve it some day :J

Is that like down loads on a computer?
It shuts down to do it?

That explanation, sort of, fits my experience.
Spoiler:
I went though a tough educational experience one time.

My head would be So Tired and Full.
I would hit a place where I was not learning.

We were told to sleep.
No one needed to tell us to sleep.

I was not the only one that fell asleep.
We were not bored. We were exhausted.

After sleep, there was room for more knowing.
One of my favorite faculty called the mind, The Bucket.

She said, "It is a leaky Bucket."
She taught us to Sleep.

I could sleep standing up, like a horse.
The urge to roll over caused some problems.
Life is, just, an exchange of electrons; It is up to us to give it meaning.

We are all in The Gutter.
Some of us see The Gutter.
Some of us see The Stars.
by mr. Oscar Wilde.

Those that want to Know; Know.
Those that do not Know; Don't tell them.
They do terrible things to people that Tell Them.

Mordrorru
Posts: 27
Joined: Fri Jan 14, 2011 9:22 am UTC

Re: 1345: "Answers"

Postby Mordrorru » Sun Mar 23, 2014 7:39 am UTC

I only know a little about this, but I think people are getting confused. It's not that scientists don't know what sleep does. They know a lot about it, and are adding more to that knowledge all the time. The thing is there's a difference between knowing what sleep does and why we to sleep to do it. None of these functions so far discovered seem to in-and-of-themselves necessitate putting the body into a dormant state, and it's hard to tell which functions (if any) are an inherent part of sleep and which have merely evolutionarily "piggy-backed" onto the process. That's where the question is.


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