That's not how I read it. But if so, if the safety of sleep is indeed an evolutionary pressure, why don't we sleep more? And why do we have to close our eyes and lose consciousness to get the benefit of this safety?
It looks (to someone who has not done any of the necessary research to draw any real, useful conclusions) that they are proposing a balance of sorts. You are safest (in this theory) when sleeping. You are likely holed up some where, hidden from view, and relatively non-moving because you are unconscious. To cope with the inherent danger of being unconscious, you are especially alert to particular sounds which may signal a coming attack. While awake, you are out, moving around, and under danger of being attacked by a predator. However, there must be a balance between the two, because there are certain things you must do to keep living (find food, eat, create shelter for the next sleep period). Its seems fairly reasonable that there is a balance point in there some place, and that it would be different based on each animal, depending on the habits of not only their prey and predators, but also how much food they must bring into their body, what kind of shelter their environment requires for sleep, and all sort of other factors.
Well, try an experiment. Find a time of day when you are alert and well-rested, and lay still in your bed with no external entertainment for eight hours
I'm not saying the idea is correct, but your argument is sorely lacking in plausibility - creatures with complex nervous systems get bored staying still unless they lose consciousness (and actually, we spend a lot of sleep with our brains still active in dream-world). If evolution "wanted" to come up with a way to keep animals out of trouble for the part of the day they'd be vulnerable, sleep might be a reasonable and generic way of doing so
It wouldn't be lying in bed motionless. It would be sitting in the cave talking quietly instead of sleeping. Or whatever.
I don't think that being asleep is safer than being awake, even in the exact same place. Why do you think someone always stays awake to guard the camp?
Oh well, not like I know what the hell I'm talking about. I just thought Siegel's explanations were too cute by half. Of course we evolved to sleep, there's nothing about us that didn't evolve. But the idea that the state of being asleep makes us safer from predators, and that's the reason for the selection? Doesn't pass the smell test IMO. Could be wrong. Been wrong before.
