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Re: Evolution of sleep



--- K and T Dykes <ktdykes@arcor.de> wrote:

<Sleep per se is common to all... vertebrates?>>
> 
> This must be another interesting question, because I
> don't know the answer
> either.  Happily, there's a good chance somebody
> else will be able to
> enlighten us both.  That's the great thing about
> ignorance.  It leaves
> plenty of room for learning new stuff.
> Cheers
> Trevor

+++++++++++++++++++++++++++++++++++++++++++++++

I'm not sure how far back sleep goes, but I know that
insects get the "honour" of being included in this
camp. Though the physiological processes that occur in
vertebrate sleep, are completely different with
insects (since they have a completely different
physiology, I'm hardly surprised). As such, insect
sleep usually gets labeled as: torpor. 

Nonetheless, insects demonstrate the same lack of
mobility and decreased response to stimuli, that is
seen in vertebrates when they sleep (i.e. they "shut
down" just like the rest of us do).

Now, do insects dream? That's what I'd like to find
out.

Aside from that, I'm left wondering if sleep is a
common trait seen in all creatures that exhibit an
ability to think (i.e. neurons capable of associating
with each other). There was a recent article in Time
magazine that dealt with sleep. The latest research on
it would seem to confirm that it is a behaviour
devoted, almost entirely, to the brain. As such, I'm
wondering if sleep is a requirement for proper
functioning of the associative neurons themselves. It
would help explain why sleep is so prevalent across
classes, and why the best some critters can do, is
only turn off half of their brains at a time.

Jason

"I am impressed by the fact that we know less about many modern [reptile] types 
than we do of many fossil groups." - Alfred S. Romer

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