[I snipped]
> I see your point. Staying awake is costly and sleep is like hybernation,
> conserves energy. But how about this: "Several animals mitigate the
> fundamental conflict between sleep and wakefulness by engaging in
> unihemispheric sleep, a unique state during which one cerebral hemisphere
> sleeps while the other remains awake..." [Behavioral, neurophysiological
> and evolutionary perspectives on unihemispheric sleep, NC Rattenborg
> et al 2000] (downloadable). This suggests that sleep is indispensible.
>> Maybe sleep has some positive functions as well as being an energy-
> -conserving state. That would explain the facts quite well.
Good point. I also do think that sleep has a necessary function. If an
animal would spend so much of it's time asleep, I would say it can do
something useful in that time. But restoration of daily-expended resources
seems unlikely. My guess would simply be that some (psychological) functions
are executed in the mode of sleep, while others are executed in the mode of
wakefulness. I must add that I am biased to think so because I'm a
behavioral scientist (in two months, actually).
> > Well, sleep is essential for the hippocampus to consolidate memory
(although
> > that theory may be old by now). During REM sleep, activation of memory
> > structures allows for a more permanent storage of memories. But still, I
> > would say the function of sleep is to avoid the encumbrance of being
awake.
>> I've read about a man went without sleep for some 40 years, and his
> memory was failing. That's pretty long for the adverse effect to set in,
> but he might have other conditions unnoticed before. I cant find any
> paper on such cases, only reading about them in books, without refs.
Don't worry about the refs, I'll take your word on this because I've heard
of something similar, although I'm not sure of the exact timespan. Anyway,
what if this man was unable to perform memory consolidation, not because his
resources had been depleted but simply because the man had never reached REM
sleep, in which memory consolidation has evolved to occur.
All this is speculative, no references given, I'm no authority in any way. I
merely wish to challenge your thoughts.
Filip
