RenaissanceBiker
Eats shoots and leaves.
Rust never sleeps.
Neither does Samara.
casebro
Penultimate Amazing
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That sounds like about half of the posters here.
Where as the other half of the posters are asleep with the other half of their brains.
I wonder how we can tell which is witch ?
Hmm, it must be true. When I spend too long at the net, sometimes my rear half falls asleep.
Gee, that's a lot of wit for this early. Maybe I should have had only half a a cup of coffee?
Speaking of wit, I maybe only half right...
Zeuzzz
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Well that doesn't make any sense.
Why do you think that our ancestors went to the bother of climbing up trees when they slept? or why animals dig burrows to sleep?
If they didn't need sleep, they wouldn't need to do these things, and could spend more time feeding and being aware of predators. Surely?
Zeuzzz
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No, being higher up or hidden keeps them them from being eaten. Being asleep does not keep them from being eaten. The very reason that they perform these actions is precisely because when they sleep they need to get into a safe place to avoid predators.
sol invictus
Philosopher
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To make themselves safe.
That's been addressed by nearly every post in this thread. Are you sleep-posting?
No you can't. That's the whole point. The mere act of being awake uses a lot of energy. The brain is hugely energy intensive, and then there are things like temperature control which are all shut down when you sleep. The ratio of sleep to wakefulness is a compromise. You need to be awake for at least some time in order to survive. Energy is the most obvious problem, but things like ensuing safety are also important. The rest of the time you want to be using as little energy as possible, which means sleep. The problem is, if you spend too much time asleep, you don't have enough time to gather energy. Similarly, if you spend too much time awake, you use up a lot more energy and may have trouble fitting everything in. Obviously the actual balance depends on the specific animal and the environment, but it is clear that it tends to be somewhere in the middle, with some animals spending more time awake than sleeping and others doing it the other way around.
alfaniner
Penultimate Amazing
Do sharks sleep? (or any fish for that matter) I seem to recall that sharks need to keep swimming to constantly process oxygen through their gills.
Besides, they don't even have any eyelids!
Besides, they don't even have any eyelids!
I beg your pardon?
Body temperature may drop a bit during sleep, but that doesn't mean that temperature control is shut down when you sleep.
paximperium
Penultimate Amazing
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You have things backwards and you seem to have this belief that evolutionary traits are directed.
Climbing and digging behavior developed as a way to prevent night predators from killing you when you sleep. A hidden animal is not easy to get to. You forget, warm blooded animals are a recent development and most animals, especially cold blooded creatures, hibernate and sleep at the night time. This saves energy.
Being awake uses up tremendous amount of energy. A python can eat an animal and "sleep" and conserve energy for months while waiting for a prey to come by before attacking.
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Nope - but they are not animals. Plants do not sleep either. The question is about animals because, as best we know only animals sleep - and likely only animals above a certain development level (chordata definitely).
Zeuzzz
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Totally agree. Thats what I meant.
Please do not manipulate the words of other posters in order to change their meaning. Because Sol Invictus corrects this later in the thread, I won't do so here.
Replying to this modbox in thread will be off topic Posted By: LibraryLady
Clearly you are unable to understand what is being said, you just see a post by me you cant resist arguing, can you?
There are three simple things here to understand:
1) Sleeping makes animals less safe and is a disadvantage in this sense, as they are not aware of approaching predators.
2) However lots of animals are safer when they sleep.
3) They are not safer because they are sleeping, but due to the various methods they employ to remain safe while sleeping.
So if you are an animal with predators around, it is a disadvantage to sleep. Thus why I was wondering why no animals have evolved to lessen the sleep they need, or exclude it completely, as this would serve as a major advantage. This however depends on whether an animal could evolve to do the job sleep does when they are in an awake state, or they would just suffer all the usual sleep deprivation signs. This seems to be why this has not happened, animals seem not able to do the job sleep does while fully awake.
Which was what I said in the OP, and every post since it. I should also add that an organism cannot choose to evolve in a certain direction, or to acquire a particular trait. It doesn't matter how wonderful it might be, if a mutation that would permit it has never occurred, it can't happen.
However, as has been speculated above, it's possible that such a mutation HAS occurred, and turned out to NOT be adaptive, in which case it quickly disappeared from the gene pool again.
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Ivor the Engineer
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Ichneumonwasp
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No, sleep keeps them from roaming around, looking for food. Sleep actually keeps animals safe during the time period for which they are not well-adapted, night for the diurnals and day for the nocturnals. If they were in their burrows or up in trees making noise they would not be as safe as they would be asleep, and they would probably spend most of that time foraging for food anyway. Sleep is a way of keeping animals in a safe place so that they cannot be eaten during their vulnerable times.
That is probably the primary reason why sleep evolved in the first place in land animals. The function sleep (and particularly REM sleep) now serve in these same animals may now differ, since natural selection takes advantage of what is already in place, to the point where most land animals cannot function at all without sleep.
Ichneumonwasp
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Number one is incorrect. Sleeping is not a disadvantage. Most predators know about a prey's location based on movement clues. Sleeping animals move less, so sleep is, in itself, an advantage when animals are most vulnerable.
aggle-rithm
Ardent Formulist
From what I've heard, they do...in fact, the exact same chemicals that put human beings to sleep also put insects to sleep.
Apparently, it's something that appeared in a common ancestor VERY early in the evolutionary process.
How do you know that they haven't?
Ziggurat
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"Rest" and "sleep" are not synonymous. Sleep is a neurological state, and if you don't have a nervous system, you can't sleep. But even animals with nervous systems can rest without sleeping, and frequently do. I would expect that single-celled organisms only "rest" (which would really only mean slow down their metabolism) if there are periods in which they can't really feed - otherwise there's no point in resting for them.
