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Author Topic:   The Evolution Of Sleep
Straggler
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Posts: 10284
From: London England
Joined: 09-30-2006


Message 1 of 72 (636662)
10-08-2011 5:41 PM


How and why did sleep evolve? Which forms of life require sleep and which don't? What does this tell us about sleep and how it evolved? Is it possible for complex life to evolve that doesn't require sleep?

It has just occurred to me what a strange thing sleep is in a evolutionary context. A state of high vulnerability that has evolved. Why? Is there no way round it?

I have no answers or strong opinions of my own. I am just intrigued as to the purpose, need and hence evolution of sleep.


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Message 2 of 72 (636664)
10-09-2011 8:13 AM


Thread Copied from Proposed New Topics Forum
Thread copied here from the The Evolution Of Sleep thread in the Proposed New Topics forum.
    
Larni
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Posts: 3975
From: Liverpool
Joined: 09-16-2005


Message 3 of 72 (636666)
10-09-2011 9:03 AM
Reply to: Message 1 by Straggler
10-08-2011 5:41 PM


Here's some of my musings about sleep:

When it gets dark (for diurnal animals) it is very dangerous to be stumbling around in the darkness. Sleep could be really good way to immobilise the organism and conserve as much energy as possible.

We we sleep we experience sleep paralysis. If we did not we would act out our dreams. This means that when we sleep our brain is as active as when awake and something about that activity is necessary for the correct working of the brain.

There is some suggestion that brains 'de frag' when we sleep; ordering our files in a more efficient way. I personally like this: anecdotally I've spent ages on a tricky computer game only to find it easy when I've slept on it.

The various stages we go through when we sleep is quite plastic, we can condense two to three cycles into aboutvfour hours if we need to. But the fact we can't reduce it to zero and the way some animals sleep different hemispheres of the brain separately is a strong indication that sleep is biological necessary. After all, not sleeping for long enough leads to irritability, paranoia, hallucination and death.

I 'reckon' that having a complex nervous system means it 'run hot' and needs to have a refractory period where it de frags itself and this function has been co opted by organisms to conserve energy and/or stay safe during none feeding or mating times.

I've not touched on dreams but they are fascinating, too.


The above ontological example models the zero premise to BB theory. It does so by applying the relative uniformity assumption that the alleged zero event eventually ontologically progressed from the compressed alleged sub-microscopic chaos to bloom/expand into all of the present observable order, more than it models the Biblical record evidence for the existence of Jehovah, the maximal Biblical god designer.
-Attributed to Buzsaw Message 53

Moreover that view is a blatantly anti-relativistic one. I'm rather inclined to think that space being relative to time and time relative to location should make such a naive hankering to pin-point an ultimate origin of anything, an aspiration that is not even wrong.

Well, Larni, let's say I much better know what I don't want to say than how exactly say what I do.


This message is a reply to:
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Straggler
Member
Posts: 10284
From: London England
Joined: 09-30-2006


Message 4 of 72 (636667)
10-09-2011 9:43 AM
Reply to: Message 3 by Larni
10-09-2011 9:03 AM


When Did Sleep Arise In Evolutionary History?
You've obviously focused on human sleep. And that's all very on topic and fine. But from what little googling I have done on this it appears that all sorts of life on Earth sleeps. Not just mammals and reptiles but fish and even invertebrates (not sure about insects).

So at what point did sleep evolve and why?

Is it even possible for evolved complex lifeforms to exist without sleep?

If we meet intelligent aliens one day will they also need to sleep?

I have no idea. But insights from anyone who knows anything about this at all much appreciated.

Larni writes:

I've not touched on dreams but they are fascinating, too.

Indeed. If this thread catches on I'm sure we'll get onto dreams. I hope so.


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Replies to this message:
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hooah212002
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Posts: 3183
Joined: 08-12-2009


Message 5 of 72 (636668)
10-09-2011 9:49 AM
Reply to: Message 4 by Straggler
10-09-2011 9:43 AM


Re: When Did Sleep Arise In Evolutionary History?
Don't most animals have a "night watchman" so to speak? A member of the group that watches out for danger?

"Why don't you call upon your God to strike me? Oh, I forgot it's because he's fake like Thor, so bite me" -Greydon Square

This message is a reply to:
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Straggler
Member
Posts: 10284
From: London England
Joined: 09-30-2006


Message 6 of 72 (636669)
10-09-2011 10:41 AM
Reply to: Message 5 by hooah212002
10-09-2011 9:49 AM


Re: When Did Sleep Arise In Evolutionary History?
In social animals very probably. But it doesn't seem to be prerequisite for sleep to be needed.

I have just come across the notion of "unihemispheric sleep" where one half of the brain sleeps whilst the other half stays alert for threat detection etc. Apparently some birds and aquatic mammals utilise this method of sleeping. Fascinating.

Here is a wiki link on non-human sleep:

Link writes:

Unihemispheric sleep refers to sleeping with only a single cerebral hemisphere. The phenomenon has been observed in birds and aquatic mammals, as well as in several reptilian species (the latter being disputed: many reptiles behave in a way which could be construed as unihemispheric sleeping, but EEG studies have given contradictory results). Reasons for the development of unihemispheric sleep are likely that it enables the sleeping animal to receive stimuli, threats, for instance, from its environment, and that it enables the animal to fly or periodically surface to breathe when immersed in water.

More generally:

Link writes:

Sleep as a phenomenon appears to have very old evolutionary roots. The nematode C. elegans is the most primitive organism in which sleep-like states have been observed. Here, a lethargus phase occurs in short periods preceding each moult, a fact which may indicate that sleep primitively is connected to developmental processes. Raizen et al.'s results[5] furthermore suggest that sleep is necessary for changes in the neural system.

The electrophysiological study of sleep in small invertebrates is complicated. However, even such simple animals as fruit flies appear to sleep, and systematic disturbance of that state leads to cognitive disabilities.

Link

So sleep seems to be a very early developed, and hence widespread, evolutionary phenomenon indeed.


This message is a reply to:
 Message 5 by hooah212002, posted 10-09-2011 9:49 AM hooah212002 has acknowledged this reply

Replies to this message:
 Message 7 by Larni, posted 10-09-2011 11:01 AM Straggler has responded

  
Larni
Member
Posts: 3975
From: Liverpool
Joined: 09-16-2005


Message 7 of 72 (636672)
10-09-2011 11:01 AM
Reply to: Message 6 by Straggler
10-09-2011 10:41 AM


Re: When Did Sleep Arise In Evolutionary History?
As far as I can recall babies do most of their growing and sundary protien syntheses when they ae asleep.

As far as I know all animals need sleep. I 'reckon' it did not evolve specifically but was a by product of the advent of the nervous system.


The above ontological example models the zero premise to BB theory. It does so by applying the relative uniformity assumption that the alleged zero event eventually ontologically progressed from the compressed alleged sub-microscopic chaos to bloom/expand into all of the present observable order, more than it models the Biblical record evidence for the existence of Jehovah, the maximal Biblical god designer.
-Attributed to Buzsaw Message 53

Moreover that view is a blatantly anti-relativistic one. I'm rather inclined to think that space being relative to time and time relative to location should make such a naive hankering to pin-point an ultimate origin of anything, an aspiration that is not even wrong.

Well, Larni, let's say I much better know what I don't want to say than how exactly say what I do.


This message is a reply to:
 Message 6 by Straggler, posted 10-09-2011 10:41 AM Straggler has responded

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 Message 8 by Straggler, posted 10-09-2011 11:05 AM Larni has not yet responded

    
Straggler
Member
Posts: 10284
From: London England
Joined: 09-30-2006


Message 8 of 72 (636673)
10-09-2011 11:05 AM
Reply to: Message 7 by Larni
10-09-2011 11:01 AM


Re: When Did Sleep Arise In Evolutionary History?
Larni writes:

I 'reckon' it did not evolve specifically but was a by product of the advent of the nervous system.

More than plausible.

So at what stage in the evolutionary development life did the nervous system evolve?

Are there any examples of creatures which exist today and straddle the divide between having a nervous system and not (and thus possibly straddling the sleep/non-sleep divide)


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New Cat's Eye
Inactive Member


Message 9 of 72 (636677)
10-09-2011 12:21 PM
Reply to: Message 1 by Straggler
10-08-2011 5:41 PM


How and why did sleep evolve?

It gets dark anyways, so you might as well just wait for when you can see. Being able to shut down while you're waiting and avoiding unnecessarily spending energy would be beneficial and so would the rebuilding aspects.

Which forms of life require sleep and which don't? What does this tell us about sleep and how it evolved?

Pretty much every animal sleeps in some way, so itís been important since early on. Fish and reptiles have a more primitive sleep state than birds and mammals. And even invertebrates have a shutdown mode. But I donít think non-animals sleep. I guess that as you get more complex systems within organisms, the more they need to regulate them.

Is it possible for complex life to evolve that doesn't require sleep?

I doubt it from our current state, but I suppose it would have been possible. Although, the energy input would have to be a lot higher so that might be preventative.

It has just occurred to me what a strange thing sleep is in a evolutionary context. A state of high vulnerability that has evolved. Why? Is there no way round it?

Donít forget that predator-prey relationships have to form a balance, or the preds will eat all their food, so the vulnerability thing would kind of work itself out.

I have no answers or strong opinions of my own. I am just intrigued as to the purpose, need and hence evolution of sleep.

Well this is all just me speculating.


This message is a reply to:
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Replies to this message:
 Message 11 by Straggler, posted 10-10-2011 7:59 AM New Cat's Eye has responded

  
frako
Member
Posts: 2813
From: slovenija
Joined: 09-04-2010


Message 10 of 72 (636680)
10-09-2011 1:23 PM
Reply to: Message 1 by Straggler
10-08-2011 5:41 PM


Given that virtually every animal sleeps i think sleep must somehow be necessary for normal brain function to work.

fun fact:
Dolphins sleep with only half a brain at a time because they have to be constantly concision so they do not drown.


Christianity, One woman's lie about an affair that got seriously out of hand

Jesus was a dead jew on a stick nothing more


This message is a reply to:
 Message 1 by Straggler, posted 10-08-2011 5:41 PM Straggler has not yet responded

    
Straggler
Member
Posts: 10284
From: London England
Joined: 09-30-2006


Message 11 of 72 (636706)
10-10-2011 7:59 AM
Reply to: Message 9 by New Cat's Eye
10-09-2011 12:21 PM


CS writes:

It gets dark anyways, so you might as well just wait for when you can see. Being able to shut down while you're waiting and avoiding unnecessarily spending energy would be beneficial and so would the rebuilding aspects.

The circadian rhythm does indeed seem to be a feature of most life on Earth. Including plants as well as animals. No doubt it is a contributing factor to the evolution of sleep. But creatures evolved for polar conditions (where "days" and "nights" can last months) and those that dwell in caves, underground or deep within the oceans where day/night is of much less consequence all seem to sleep as well. So it can't be the whole story.

CS writes:

Pretty much every animal sleeps in some way, so itís been important since early on. Fish and reptiles have a more primitive sleep state than birds and mammals. And even invertebrates have a shutdown mode. But I donít think non-animals sleep. I guess that as you get more complex systems within organisms, the more they need to regulate them.

Perhaps unsurprisingly single celled organisms don't exhibit any signs of anything matching sleep. But nor (apparently) do squids and octopuses. How far do we have to go back to find a common ancestor with them I wonder?

CS writes:

Although, the energy input would have to be a lot higher so that might be preventative.

Isn't most of the energy humans consume taken up by the brain? And (as I understand it) the brain isn't really less active when we sleep. I might need to check my facts here. Also dolphins swim whilst asleep and birds fly!!! (mad!!). So how much energy is really being saved?

CS writes:

Donít forget that predator-prey relationships have to form a balance, or the preds will eat all their food, so the vulnerability thing would kind of work itself out.

In the evolutionary arms race wouldn't it be a case (if possible) ever less sleep and improved nocturnal abilities rather than everyone agreeing to take the night off?

Strags writes:

Is it possible for complex life to evolve that doesn't require sleep?

CS writes:

I doubt it from our current state, but I suppose it would have been possible.

I am intrigued by the idea of intelligent evolved life that doesn't need to sleep. If it is possible then maybe one day we will meet some alien cousins who will consider our need to spend 30% of our life unconscious thoroughly and bewilderingly inefficient.

If of course the squids and octopuses haven't taken over by then....

Edited by Straggler, : No reason given.


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Replies to this message:
 Message 12 by New Cat's Eye, posted 10-10-2011 10:26 AM Straggler has responded
 Message 13 by caffeine, posted 10-10-2011 11:04 AM Straggler has responded
 Message 14 by Larni, posted 10-10-2011 11:16 AM Straggler has responded

  
New Cat's Eye
Inactive Member


Message 12 of 72 (636724)
10-10-2011 10:26 AM
Reply to: Message 11 by Straggler
10-10-2011 7:59 AM


The circadian rhythm does indeed seem to be a feature of most life on Earth. Including plants as well as animals. No doubt it is a contributing factor to the evolution of sleep. But creatures evolved for polar conditions (where "days" and "nights" can last months) and those that dwell in caves, underground or deep within the oceans where day/night is of much less consequence all seem to sleep as well. So it can't be the whole story.

Well, it could be... If the circadian rhythm was already a part of their evolution before they got to the poles/caves.

Perhaps unsurprisingly single celled organisms don't exhibit any signs of anything matching sleep. But nor (apparently) do squids and octopuses. How far do we have to go back to find a common ancestor with them I wonder?

If we're going back that far, I'd prolly bet that sleep evolved independently between Protostomes and Deuterostomes. Protosomes splits into antropods, flat worms, and mollusks (etc) while Dueterostomes splits into urchins, round worms and vertebrates (etc). I think that there's some disparity between the sleep that these two groups exhibit, so that could suggests its unrelated.

Isn't most of the energy humans consume taken up by the brain? And (as I understand it) the brain isn't really less active when we sleep. I might need to check my facts here.

I don't know, but there's also a lot of "rebuilding" that goes on during sleep, which would still count as 'activity' even though its helping. Its still gonna require energy, but you're not doing all that other activity as well. If you didn't sleep, then you'd have to be rebuilding while you're doing your normal activities, and then all that together would require that much more energy.

Also dolphins swim whilst asleep and birds fly!!! (mad!!). So how much energy is really being saved?

Adaptations to sleep that arrise after sleep has already evolved isn't gonna help us much in figuring out how sleep evolved in the beginning. To contrast: How much energy does a brown bear save during its hybernation?

Donít forget that predator-prey relationships have to form a balance, or the preds will eat all their food, so the vulnerability thing would kind of work itself out.

In the evolutionary arms race wouldn't it be a case (if possible) ever less sleep and improved nocturnal abilities rather than everyone agreeing to take the night off?

That's not really what I was thinking... Preds that took too much advantage of sleeping prey wouldn't have survived, so we'd just be left with the ones that didn't. I see it as more of a balancing act than an arms race.

I am intrigued by the idea of intelligent evolved life that doesn't need to sleep. If it is possible then maybe one day we will meet some alien cousins who will consider our need to spend 30% of our life unconscious thoroughly and bewilderingly inefficient.

With aliens, having their own circadian rhythm, the sky's the limit...

But sleep seems like a good idea to me. Everything degrades and nothing can run forever, it just makes sense to take a break every so often. Would you prefer to never have to sleep but then just have a lifespan that was 30% shorter? Would you sleep more for a longer life?


This message is a reply to:
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caffeine
Member
Posts: 1600
From: Prague, Czech Republic
Joined: 10-22-2008
Member Rating: 2.4


Message 13 of 72 (636726)
10-10-2011 11:04 AM
Reply to: Message 11 by Straggler
10-10-2011 7:59 AM


Perhaps unsurprisingly single celled organisms don't exhibit any signs of anything matching sleep. But nor (apparently) do squids and octopuses. How far do we have to go back to find a common ancestor with them I wonder?

Well, our ancestry with squid is a very long time ago, but are you sure they don't sleep? I had a look and found this article on Discover about cephalopod intelligence, which has this to say about sleep:

quote:
Meanwhile, Anderson has been investigating another phenomenon little-noted in invertebrates: sleep. Until recently, only vertebrates were believed to sleep in the full metabolic sense. But Anderson has observed that octopuses, ordinarily hypervigilant, may sleep deeply. Their eyes glaze over, their breathing turns slow and shallow, they don't respond to light taps, and a male will let his delicate ligulaóthe sex organ at the tip of one armódangle perilously.

Stephen Duntley, a sleep specialist at Washington University Medical School in St. Louis, has videotaped similar slumber in cuttlefish, with a twist: Sleeping cuttlefish lie still, their skin a dull brown, for 10- to 15-minute stretches, then flash bold colored patterns and twitch their tentacles for briefer intervals. After viewing Duntley's footage, Anderson suggests the cuttlefish might merely be waking to check for threats. But Duntley says the cycling resembles the rapid eye movement sleep of birds and mammals, when humans dream. If invertebrates undergo a similar cycle, Duntley argues, it would affirm "that REM sleep is very important to learning." Would it also suggest that cuttlefish and octopuses dream? "That's the ultimate question," Duntley responds.


Isn't most of the energy humans consume taken up by the brain?

20% of energy consumption seems to be the most commonly cited figure.


This message is a reply to:
 Message 11 by Straggler, posted 10-10-2011 7:59 AM Straggler has responded

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Larni
Member
Posts: 3975
From: Liverpool
Joined: 09-16-2005


Message 14 of 72 (636729)
10-10-2011 11:16 AM
Reply to: Message 11 by Straggler
10-10-2011 7:59 AM


Isn't most of the energy humans consume taken up by the brain? And (as I understand it) the brain isn't really less active when we sleep. I might need to check my facts here. Also dolphins swim whilst asleep and birds fly!!! (mad!!). So how much energy is really being saved?

It is true that the human brain is musts as active as when it is awake so I don't see sleep as an energy saver: the energy saved comes from over all inactivity.

Swimming dolphins and flying swifts does so not wholes asleep but by shutting down one hemispher of their brains so they are never unconscious.

I would imagine this could be the same in Cephalopoda, too. I've octopuses go into what looks like a refractory period and always assumed they were having a kip.

I would hazard that organisms probably could exist that do not need sleep but they would be out competed by ones that do sleep. That's why we don't see any and organisms that would logically be better off without it (dolphins and swifts) not needing to sleep but have convoluted work arounds (sleeping one hemisphere at a time).


The above ontological example models the zero premise to BB theory. It does so by applying the relative uniformity assumption that the alleged zero event eventually ontologically progressed from the compressed alleged sub-microscopic chaos to bloom/expand into all of the present observable order, more than it models the Biblical record evidence for the existence of Jehovah, the maximal Biblical god designer.
-Attributed to Buzsaw Message 53

Moreover that view is a blatantly anti-relativistic one. I'm rather inclined to think that space being relative to time and time relative to location should make such a naive hankering to pin-point an ultimate origin of anything, an aspiration that is not even wrong.

Well, Larni, let's say I much better know what I don't want to say than how exactly say what I do.


This message is a reply to:
 Message 11 by Straggler, posted 10-10-2011 7:59 AM Straggler has responded

Replies to this message:
 Message 16 by Straggler, posted 10-10-2011 11:26 AM Larni has responded

    
Larni
Member
Posts: 3975
From: Liverpool
Joined: 09-16-2005


Message 15 of 72 (636731)
10-10-2011 11:20 AM
Reply to: Message 12 by New Cat's Eye
10-10-2011 10:26 AM


To contrast: How much energy does a brown bear save during its hybernation?

Forgive my pedantry: bears go into torpor, rather than hibernation.


The above ontological example models the zero premise to BB theory. It does so by applying the relative uniformity assumption that the alleged zero event eventually ontologically progressed from the compressed alleged sub-microscopic chaos to bloom/expand into all of the present observable order, more than it models the Biblical record evidence for the existence of Jehovah, the maximal Biblical god designer.
-Attributed to Buzsaw Message 53

Moreover that view is a blatantly anti-relativistic one. I'm rather inclined to think that space being relative to time and time relative to location should make such a naive hankering to pin-point an ultimate origin of anything, an aspiration that is not even wrong.

Well, Larni, let's say I much better know what I don't want to say than how exactly say what I do.


This message is a reply to:
 Message 12 by New Cat's Eye, posted 10-10-2011 10:26 AM New Cat's Eye has not yet responded

    
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