

People who are sleep deprived have no sense of their limitations - stillmotion
http://www.cbsnews.com/stories/2008/03/14/60minutes/main3939721.shtml

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tim2
Actually, when the article says:

> people who are chronically sleep deprived, like people who've had too much
> to drink, often have no sense of their limitations.

What it means is that people don't realize _the degree to which_ they are
being inhibited (although the studies did not test this, this is based on one
piece of anecdote.) The article is not saying that people think that their
limitations are greater than they otherwise would, as is the case with alcohol
or testosterone.

------
jauco
> It would be the biggest evolutionary mistake if sleep does not serve some
> critical function," Walker says.

it's a minor quote from the whole article, but sentences like these always
annoy me: Evolution does not make mistakes! It's not an It! it doesn't do!

Evolution's simply a term that describes change. You should treat it like the
term "moving". As in "Creature a moved to B" <=> "Creature A evolved to B" how
silly would it be to say that movement made a mistake.

And even if we forget syntax and focus on what the sentence implies the
sentence is overly bold. If we sleep, then somewhere along our ancestry,
creatures that slept survived. That's about all you can say. Maybe sleepers
where unfit for life if strange virus X hadn't wiped out all non-sleeping
superior lifeforms. Or whatever. Don't infer based on the fact that something
is as it is, that it is therefore superior to all other possibilities.

~~~
mechanical_fish
I agree that the "mistake" phrasing is atrocious.

I don't exactly agree with this, though:

 _Don't infer based on the fact that something is as it is, that it is
therefore superior to all other possibilities._

Actually, we _can_ conclude that there must be a good reason why the average
human needs eight hours of sleep, as opposed to four hours or two hours or
half an hour. It's not as if we can't get there from here: Some living humans
really _do_ need only four hours of sleep. And other creatures, not so
different from us, have much niftier tricks: Bears can sleep for four months
straight, horses can sleep very lightly while standing up, my parrot wakes up
at almost _any_ stimulus, some creatures sleep with half the brain at once,
etc. If sleep were a big liability, there seem to be lots of genetic switches
that could be thrown to reduce, alter, or eliminate it. The fact that those
switches have not been thrown in us suggests that our sleep pattern is an
equilibrium point in evolutionary space.

Now, maybe you're trying to say that, although there might be a way to design
a brain that didn't need sleep -- perhaps scientists will use futuristic
neuron-CAD software to figure that out, someday -- some accident in early
evolution sent us down this particular branch, and now we can't get there from
here. That's true, and it's really fascinating. It seems that creatures
without sleep would have to evolve nearly from scratch -- because even _fruit
flies_ sleep (a fact that I didn't know until today) which suggests that you
have to go back past our common ancestor with the _insects_ to find a creature
that wasn't designed around sleep. And if such a creature with a prototype
sleep-free brain tried to start up shop today, odds are it or its descendents
would all be eaten by fish before they got very far. It's hard to evict
species from an ecological niche, particularly when you're going up against
_nearly every animal species on earth_.

~~~
jauco
_Actually, we can conclude that there must be a good reason why the average
human needs eight hours of sleep, as opposed to four hours or two hours or
half an hour._

 _Now, maybe you're trying to say that some accident in early evolution sent
us down this particular branch, and now we can't get there from here. That's
true, and it's really fascinating._

That was indeed the idea behind my previous post. Rather the same thing
happens with humans only changing teeth once a lifetime instead of
continuously. There is some evidence that changing once doesn't give us an
evolutionary advantage, but is simply a leftover from some ancestor's trait
way back. (I'll see if I can find the reference).

I'm not saying that humans might not need their sleep (we die if we are sleep
deprived), but that, based on the fact that we sleep, you can't claim that
sleeping creatures have an advantage over hypothetical non-sleeping creatures.
Maybe it's just something that stuck and doesn't do enough harm to kill us all
out.

