> This quote from Science vol 321 July 18 08 'Simple Sleepers' seems to
> somewhat support some of my ideas on sleep. To summarize, I suggest that
> sleep is a two part process with the first, deep sleep, a time of rebuilding
> and dealing with nurturing; and, the second REM sleep period is a time of
> preparing waste out.
>
> It turns out that mammals and birds are not the only creatures that sleep.
> Now we have to add fish, flies and worms.
> Perhaps some of these
> organisms can give us sleep clues.
>
> "One way to get at the basic cellular purpose of sleep is to compare which
> genes and proteins are active only during sleeping or waking. In mice, rats,
> sparrows, and flies, numerous genes involved in protein synthesis and cho-
> lesterol metabolism work mainly during sleep. An accumulation of such
> research, including their own mouse studies, led Pack and colleagues to
> propose in 2007 that a key function for sleep is to give the body time and
> energy to rebuild molecules that are used up during waking. The C. elegans
> nap cycle squares with this idea, Raizen says. During lethargus, the worms
> synthesize a new skin- like cuticle and double the cell nuclei in their
> intestines, even though the cells themselves don't divide. "Those are two
> intensely bio- synthetic events," he says. "
>
> And note this on worm sleep:
>
> "The worm, however, has an odd sleep
> schedule. From the time it hatches, C. elegans takes just a few days to
> mature. Rather than sleep daily like flies and other animals, the growing
> worm takes a 2-hour nap (a state called lethargus) every 7 to 12 hours at
> each of four developmental transitions. During these periods, the worm
> builds a new cuticle, restructures body parts, and, finally, reaches sexual
> maturity. From then on, at least in the lab, the worm never sleeps again.
> David Raizen, a neurologist who studies C. elegans sleep at the University
> of Pennsylvania Med- ical School, says the contrast to mammalian sleep is
> actually a good thing: Lethargus is so different that anything the two have
> in com- mon is probably important to sleep's universal function. "The
> trick," Raizen says, "is to look at similarities."