If evolution is so great, why do we need…

…to sleep?

As was seen in the How Much Sleep? thread in MPSIMS (I can’t find it) the amount of sleep an individual needs varies. In a given population of animals, would not those that needed less sleep have more time for gathering food, finding mates, drinking beer, etc.? There is a definite advantage to sleeping less. When one is sleeping, one is a bit more vulnerable to falling victim to nocturnal predators. There is a definite disadvantage to sleeping more. Would not those animals who sleep less have an advantage over their sleepy brethren? If need for sleep is a genetic trait, wouldn’t the proportion of night-owls in a population grow? Why then, has sleep not been relegated to the evolutionary backwaters?
[disclaimer] I don’t have any doubt that evolution is the driving force behind change over time. If I did, I would have asked this in the [Evidence"]http://www.straightdope.com/ubb/Forum7/HTML/000696.html]Evidence]( [url="http://www.straightdope.com/ubb/Forum7/HTML/000696.html) Against thread.[/disclaimer]

Once in a while you can get shown the light
in the strangest of places
if you look at it right…

There may be disadvantages to sleeping, but what about the advantages? What about what the body does during sleep? Now, we’re not entirely sure what goes on, but indications are that learning is helped, the brain needs sleep to process information, healing of the body is helped, etc. These are all advantages that outweigh the disadvantages of being vulnerable. Of course, having a societal structure (which many animals have) further reduces the disadvantage of sleeping because others can keep an eye out while you’re taking a snooze.

One advantage to sleep might be is that it keeps you immobile and quiet while predators are roaming about. If we stumbled about in the dark all night, predators would find it a lot easier to track us down and eat us. We may be more vunerable if actually found by the critters, but we’ll probably wake up once they start gnawing on us, so we just miss the intial attack. Lots of animals don’t eat carrion, too, so sleep might be a method of “playing possum”.

“…Mithras the Sun-God
Is a solar myth they say,
But the Gnostics know
He obeyed the crow
And he killed that bull one day…” Happy Mithrasmas, all!

Side note: there’s a short story on this called “Beggars in Spain” where they figure out how to make humans do without sleep. All the non-sleepers are more successful, since they get an extra 8 hours a day to study or work, so they face a lot of prejudice from the sleepers.

I’ve heard a theory … well, I’ve heard gab, but I think there’s a theory behind it, that one reason for the persistence of seasonal affective disorder is that sleeping a lot is a good survival method for northerly people. It doesn’t help to gather food if there isn’t any; if you’re relying on food you stored the previous fall you’d better sleep as much as possible. And if it’s subzero outside you should stay inside as much as possible. So maybe SAD is a way of keeping grumpy Norsemen from getting restless and wandering around in the snow, looking for food which won’t be back until April.

It could be thought of that SAD is an evolutionary predecessor of hybernation, although the interbreeding of SAD north people with cheery southerners has almost certainly closed this pathway.

There is also the oft-forgotten fact that evolution is not directed. First some animal has to get a randomly acquired trait for doing with less sleep. Then that animal has to be sufficiently successful to pass on those genes and their descendants have to be successful enough to pass the genes on again. In the midst of this, these gene-bearers have to find mates from among those who do not have the trait. Ultimately, those bearing the non-sleep genes have to be so much more successful that they begin to overwhelm the population with their success (in day-to-day life, as in Gaudere’s story) in order to pass on their success in reproduction.

The genetic development of this trait may, indeed, be among us and we are simply too close to its origin to see its effect in the population.

(Ironically, most of the people of whom I have heard that they lived on only 2 - 3 hours of sleep per night were bachelor males. This is purely anecdotal, of course, but if the gene popped up in a non-reproducing population, it wouldn’t get out among the rest of us very quickly.)


Short answer: no one knows.

Long answer: Almost all animals show a circadian rest/activity cycle. “True” sleep has only been demonstrated in birds and mammals, with reptiles showing an analogous brain-wave pattern during their rest cycle. Fish and amphibians exhibit a deep rest stage, but the there has not been a heck of a lot of work done on interpreting their EEGs. Anything with a less complicated nervous system seems to only need rest and not the torpor associated with sleep.

Sleep seems to be a time when an animal with a complex nervous system does the maintenance work on its system. We know from sleep deprivation experiments that humans deprived of the REM stage of sleep feel rested, but their brains start producing all sorts of hallucinations. Dreaming may be the time when the brain catalogs and files the stimuli it has received during the day. Mammals with more complex brains tend to exhibit a greater amount of REM sleep patterns than “dumber” mammals.

Sleep seems to be a side effect of the possession of a complex nervous system. The more it can do, the more comprehensive the down-time needed for regular maintenance.

I must be one smart cookie cause I sleep all day…heheheheheeh

All jokes aside. I have gone without sleep for several weeks. Got lost for a while(mentally) and that was not much fun. I lost my apetite, health, etc. I think that sleep is necessary to function to your highest potential. So in other words, if you just wanna half ass it all day and pace yourself, you may be able to pull it off.

One Love–Robert Nesta Marley

tomndebb wrote:

Bachelor males are only non-reproducing if they remember to bring contraceptives with them on those all-night shindigs…

Fixing Rhythmdvl’s link: www.straighdope.com/ubb/Forum7/HTML/000696.html


Now I need to fix MINE!!! :frowning: :o

Where’s that LBMB “Angry Face” when you need it?!?!?!


How come we don’t have built-in nuclear reactors so we don’t have to eat, and laser beams that shoot out of our eyes? Wouldn’t that be an evolutionary advantage?

Look! Food! Use your eye lasers! ZAP

Actually, sleeping probably increases our life span by quite a bit. Remember, your metabolism goes down while you’re asleep. I think it does, at least. I mean, I can drink a liter of water, sleep for nine hours, and wake up with a bladder that says “Yo! It’s been about an hour and a half since you drank that water, you wanna go somewhere or should I let go right here?” That is, if I’d waited an hour and a half without going, my bladder would have given me the same sense of urgency. And I go to bed after a liter of water pretty often.

So let’s say that your metabolism (minus the brain, which is still active, and not counting all you active sleepers) slows down by a factor of a lot because you just aren’t moving. Let’s say that factor is 1/6, using my bladder’s functionality as analogous to the rest of the body.

So, assuming that you only age 1/6th of the time you spend asleep, and assuming you get eight hours of sleep a night, you’re really only living about 17 hours a day. So you’re effectively performing a night-day time warp that takes an unremembered hour. So, from one day to the next, you live 17 hours and go through 24. You’re actually aging at a rate of 17/24. You see what I’m saying?

So, at our rate of 17/24, over the course of 80 years… So how long would we live without that sleep? Well, 80 years times 365.25 days per year times 24 hours per day, comes to (calculator time) 701,280 hours in a lifetime. So we live 17 hrs per 24 hrs (our life rate is a unitless number) how long would we have lived WITHOUT sleep? Well, just multiply the hours in a lifetime by our liferate, and you come up with 496,740 hours. That’s only 56 and two-thirds years.

Sleeping gives uss an extra 200,000 hours of life. Because we couldn’t do anything during the dark hours anyway, sleep is an evolutionary ADVANTAGE. It gives us an extra 30 years of life to do things in, eh?

Evolution may be perfect, but that doesn’t mean that it has created the perfect creature yet. Evolution is an ongoing project, not a mythical snap of the fingers to create something.

Anyone who truely beleives in evolution will admit that humans are not perfect.

What does that mean?

“It is lucky for rulers that men do not think.” — Adolf Hitler

Just a side note on the story Gaudere mentioned.

“Beggars in Spain” by Nancy Kress is now a full blown novel, with two full blown sequels, which I recommend to anybody who likes science fiction.
The sequels are: “Beggars and Choosers” and “Beggar’s Ride”

Libertarian wrote:

It’s a personal insult against you, Libertarian! He’s sayin’ yo mamma wears army boots! Are you gonna sit there and take it? Are you gonna just let him talk trash to yo mamma like that? C’mon! Put up your dukes! Fight like a man!

– tracer, who has ten bucks riding on this fight.

Evolution may be perfect…

Evolution (n.) – The continuous genetic adaptation of organisms or species to the environment by the integration agencies of selection, hybridization, inbreeding, and mutation.

May (v. pres.) – used as an auxiliary to express: a. possibility, opportunity, or permission, b. wish or prayer, c. contingency, esp. in clauses expressing condition, concession, purpose, result, etc. d. ability or power (more commonly can.)

Be (v. pres. indic. sing.) – 1. to exist; have reality; live; take place; occur; remain as before.

Perfect (adj.) – 1. in a state proper to a thing when completed; have all essential elements, characteristics, etc., lacking in no respect; complete. 2. in a state of complete excellence; without blemish or defect; faultless. 3. completely skilled. 4. Completely corresponding to a type or description; exact.

And in three whole days, no one even NOTICES my post? I would be insulted if only I didn’t know my post was just a piece of silly fluff.

Anyway, the question has been answered. Sleep does a whole lot of stuff for us, we don’t really understand everything it does, and hey, we’re not at the end of the road yet. Evolution’s a wild ride, let’s see where it takes us (I’ll be surprised if I’m still alive to see it :slight_smile: ).