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Member (Idle past 92 days) Posts: 10333 From: London England Joined: |
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Author | Topic: The Evolution Of Sleep | |||||||||||||||||||||||
Straggler Member (Idle past 92 days) Posts: 10333 From: London England Joined: |
Larni writes: I remember some study about brain activity inducing tiredness (there seemed to be no significant difference between doing book learning and going on many fair ground rides). That raises the question of what makes us tired. How do we know/recognise when we are tired? What triggers it? Is it some sort of chemical/hormone? Can we learn anything about the biological nature of sleep from studying narcoleptics and insomniacs?
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Larni Member Posts: 4000 From: Liverpool Joined: |
Is it some sort of chemical/hormone? Yes. Adenosine: it builds up while we are awake and dgreades when we are asleep.
Can we learn anything about the biological nature of sleep from studying narcoleptics and insomniacs? We do, but sleep disorders are often not normal sleep so it's harder to generalise from. Edited by Larni, : No reason given.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.
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caffeine Member (Idle past 1050 days) Posts: 1800 From: Prague, Czech Republic Joined: |
But isn't that like saying that if Cheetahs got too fast they'd all die out from over-eating? Whilst it might be logically true the incremental nature of change means that it doesn't happen like that. The Cheetah gets a bit faster and then the antelope does too (or vice versa) and the whole thing is kept in balance through graduality. But the ultimate result is escalation. So why not the same with regard to preying on sleepers? I'm not sure if this applies generally to predator/prey relationships (although I suspect it does), but since you're talking cheetahs, grazers on the African plains tend to sleep much, much less than the hunters. Whereas hunters will happily spend more than half the day asleep (lions average something silly like 16 hours a day), antelope only sleep a few hours, and this they do in short naps, whilst standing up, and are easily startled awake by loud noises. I imagine the antelope are pushing the limits of what you can get away with; and it probably makes more sense from an energy efficiency point of view for the lions to not directly compete on the sleep front, instead conserving energy for as long as possible between meals. If they catch sufficient meals in their few hours of wakefulness anyway, why increase your energy demands by only sleeping a quarter as often? Edited by caffeine, : No reason given.
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Straggler Member (Idle past 92 days) Posts: 10333 From: London England Joined: |
But even when awake it is possible to have very vivid hallucinations and visions (I'm not knowingly prone to such things but I have experienced my share of recreational drugs). And if I close my eyes I can very clearly imagine the face of my son (for example) who I last saw a couple of hours ago.
So I don't think such clarity is necessarily a feature of dreams specifically.
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Larni Member Posts: 4000 From: Liverpool Joined: |
But here you are talking about two different things: sleep and dreams.
The act of being asleep can have more than one function.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.
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Straggler Member (Idle past 92 days) Posts: 10333 From: London England Joined: |
Larni writes: The act of being asleep can have more than one function. I agree. I'm just not convinced by GDR's idea that images within dreams are necessarily superior. I suspect the main difference is that when we dream it seems more real because we are not consciously aware that we are dreaming and that it isn't real. Or something like that.
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New Cat's Eye Inactive Member |
But that still wouldn't fully explain fish or deep sea dwellers would it? If they evolved to their places after sleep had already evolved, it could still... but yeah, I doubt the circadian rhythm is the entire explanation. Energy regulation should be a big factor too. But fish do have a more primitive form of sleep.
If that is correct - That sleep has evolved along two independent strands - It adds weight to the notion that it is something that most complex lifeforms will do. So - In the same way we might expect alien lifeforms to possess "eyes" of some sort (because they are bloody useful and have evolved independently in a number of forms) - It seems aliens might well sleep too. Bizzarre. I'm still not seeing what's so bizarre about it? Seems like a good idea to me...
If we develop Artificial Intelligence would we expect to implement periods of sleep into our inventions? Kinda defrag time? Well, my computer does have a sleep mode (although nothing really happens during it). Don't most of the droids in Sci-Fi have it too? Is there any reason to think that we wouldn't? Nothing runs forever and everything wears down, so it makes sense to delay the inevitable with a sleep mode.
But isn't that like saying that if Cheetahs got too fast they'd all die out from over-eating? Wouldn't they?
Whilst it might be logically true the incremental nature of change means that it doesn't happen like that. The Cheetah gets a bit faster and then the antelope does too (or vice versa) and the whole thing is kept in balance through graduality. But the ultimate result is escalation. So why not the same with regard to preying on sleepers? You said it right there, even with an ultimate result of escalation, the whole thing is kept in blance through graduality. If having a sleep state means having to spend less energy, then that benefit could be the selective pressure away from an arms race to sleeplessness.
Well forever is a long time. But given the ability of organisms to repair themselves I don't see why the limit has to be tens of years rather than much longer. Trees live for centuries. Why, in theory, couldn't brains? I suppose they could, but then, what kind of energy input is that going to require? How much would you need if you had to do all your repair work while you were running at full speed? Would that be sustainable? So instead of sleeping at night, you just have to be eating the whole time? Would that really be better? Shit, now I got to get another job to pay for all this extra food I need, or I could just shut down instead.
CS writes: ...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? But I'm not sure why those have to be the choices. Would you want an engine that you never had to turn off but that you had to change the oil in on your way to work? Is your question why the oil doesn't just work longer? Or why there's no perfect engine?
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Straggler Member (Idle past 92 days) Posts: 10333 From: London England Joined: |
CS writes: Would you want an engine that you never had to turn off but that you had to change the oil in on your way to work? Is your question why the oil doesn't just work longer? Or why there's no perfect engine? Oh I don't know. It just occurred to me how odd sleep is in an evolutionary context. Apparently I find it more odd than most. Although some googling around suggests that the question of why exactly we sleep is at least deemed an interesting scientific question that we have yet to fully answer. The fact that all complex lifeforms do seem to sleep and that it seems to have evolved at least twice independently (to our knowledge) suggests that there is something rather fundamental about it. I suppose what I am asking (to put it into geek speak) is why it is that despite all our seeming biological refinements we are more like Windows operating systems than UNIX. Windows needs to rebooted all the blasted time whilst my record for a UNIX box is seven years and counting. But now I am just letting my work frustrations infringe on the far more important activity of internet foruming......
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caffeine Member (Idle past 1050 days) Posts: 1800 From: Prague, Czech Republic Joined: |
The fact that all complex lifeforms do seem to sleep and that it seems to have evolved at least twice independently (to our knowledge) suggests that there is something rather fundamental about it. Where did we establish that it evolved independently in deuterostomes and protostomes? Catholic Scientist threw it out there, but I can't find any evidence anywhere for the idea. If sleep is so widespread even in quite simple animals, a single origin seems the default assumption to me.
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Straggler Member (Idle past 92 days) Posts: 10333 From: London England Joined: |
Fair point.
In my own ignorance I took CS's speculations to be more authoritative than even he probably intended. I can't find any support for this claim either. And I agree that it seems more likely that the origin lies in a common ancestor to both. Which makes sleep something that arose very very very early in our evolutionary past. So where does that leave us on the 'Would evolved aliens also likely sleep?' question?
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GDR Member Posts: 6202 From: Sidney, BC, Canada Joined: Member Rating: 2.1 |
Straggler writes: So I don't think such clarity is necessarily a feature of dreams specifically. I don't actually have a point in all of this except that I find it strange. I can look at a face, close my eyes and create a mental picture. The mental picture I get is a memory of what I was just looking at. In my dreams however, it is much more like what I experience when I'm awake with my eyes open and in some cases I dream of things and people of which I have no memory. With a bit of circular reasoning I think that it has something to do with the consciousness or mind being a reality that isn't a physical reality. That however is JMHO. I think dreams have a lot to do with needing sleep and so I think that discussing dreams is consistent with the theme of this thread. I thought I’d add that before some sharp eyed admin tells me I’m off topic. Everybody is entitled to my opinion.
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New Cat's Eye Inactive Member |
It just occurred to me how odd sleep is in an evolutionary context. Apparently I find it more odd than most. Why do you find it so odd? Anything besides the pred-prey relationship?
The fact that all complex lifeforms do seem to sleep and that it seems to have evolved at least twice independently (to our knowledge) suggests that there is something rather fundamental about it. Life evolved on a planet that was dark half the time...
I suppose what I am asking (to put it into geek speak) is why it is that despite all our seeming biological refinements we are more like Windows operating systems than UNIX. Windows needs to rebooted all the blasted time whilst my record for a UNIX box is seven years and counting. Sounds like the creationist musings on why evolution didn't give us eagle vision... There's lots of "issues" like that because you only have to evolve to be good enough.
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Straggler Member (Idle past 92 days) Posts: 10333 From: London England Joined: |
CS writes: Why do you find it so odd? Anything besides the pred-prey relationship? The apparent inefficiency of it. The vulnerable state it leaves us in. The fact that a whole mechanism for allowing our imagination to run wild (i.e. dreaming) whilst restricting us from acting out these fantasies (we apparently undergo a sort of mild induced form of paralysis whilst REM sleeping) has evolved. The fact that despite all of us all doing it (along with practically every other complex living thing on the planet) scientists still don't really understand why we do it or how exactly it works. The strangeness of phenomena like sleepwalking (people have apparently sent emails and even cooked whilst asleep!!!), narcolepsy and insomnia. The lack of rhyme or reason in how much sleep is needed (a giraffe needs less than 2 hours of sleep a day and an elephant about 3 - Why? I would have thought size would make sleep more necessary). Etc. etc. etc. In general it just seems to be a very strange and interesting phenomenon. It just made me think - How the hell did that evolve? Apart from anything else with a five year old and one year old it is something which I am desperately short of and something which is much on my mind.
Link writes: The first rapid eye movement (REM) period usually begins about 70 to 90 minutes after we fall asleep. We have around three to five REM episodes a night. Although we are not conscious, the brain is very active - often more so than when we are awake. This is the period when most dreams occur. Our eyes dart around (hence the name), our breathing rate and blood pressure rise. However, our bodies are effectively paralysed, said to be nature's way of preventing us from acting out our dreams. Link writes: So why do we sleep? This is a question that has baffled scientists for centuries and the answer is, no one is really sure. Some believe that sleep gives the body a chance to recuperate from the day's activities but in reality, the amount of energy saved by sleeping for even eight hours is miniscule - about 50 kCal, the same amount of energy in a piece of toast. Link writes: Python 18 hrsTiger 15.8 hrs Cat 12.1 hrs Chimpanzee 9.7 hrs Sheep 3.8 hrs African elephant 3.3 hrs Giraffe 1.9 hr Link Link writes: Sleepwalkers have been described to be involved in complex motor activities like cooking, eating, driving a car, playing an instrument, stabbing and murder Link Edited by Straggler, : No reason given.
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Straggler Member (Idle past 92 days) Posts: 10333 From: London England Joined: |
GDR writes: With a bit of circular reasoning I think that it has something to do with the consciousness or mind being a reality that isn't a physical reality. Whilst the mind body problem is a fascinating topic in itself (maybe I'll start a thread at some point) but let's not explicitly go there here. But on that note....You must admit that physical things (e.g. drugs) can induce dream like states, hallucinations and all of the other things that you seem to consider non-physical. Isn't sleep (and dreaming) just bio-chemistry at the end of the day?
GDR writes: I think dreams have a lot to do with needing sleep and so I think that discussing dreams is consistent with the theme of this thread. I thought I’d add that before some sharp eyed admin tells me I’m off topic. Well if I have any say as the starter of the topic I would like to agree with you in a bid to keep those sharp eyed admins at bay.
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Straggler Member (Idle past 92 days) Posts: 10333 From: London England Joined: |
If I were a creationist looking for a gap I think the whole issue of sleep and dreaming would be rife with opportunity. No obvious evolutionary explanation agreed upon by science as a whole and lots of opportunity for subjective mysticism regarding dreams and the like.
This isn't an invite. Just an observation.
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