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-RA-
#6
Oct17-07, 03:27 PM
P: 88
Quote Quote by jim mcnamara View Post
Go to a field where you cannot see any electric lights closer than 100 yards or so. Go out on a dark moonless night.

Try to walk about. You will personally experience why some researchers think being awake at night and moving around was a bad idea for early humans. While you are stumbling around, pretend there are predators nearby. They can silently run 40mph, too. And you are on the menu.
point taken, although i think i'll leave the experiment for someone else to try!. I suppose that is a good reason for mammals with bad night vision; but what about animals that hunt at night, aswell as the day? they still sleep periodically.

Quote Quote by mgb_phys View Post
If you are hiding in hole during the day it makes sense to reduce your energy demands by slowing down that calorie hungry brain so that when you do go out looking for food you don't need to find so much.
i can understand that aswell, but i also cant see why we have to sleep to replenish our brains in the first place. An animal with a brain that 'replenishes' as it is use, and so would never need to rest, would be at a much bigger advantage than animals that do rest. I would have thought that over time some animals would have developed to not need sleep as it would be so advantageous.

I guess in an indirect way i am asking why exactly do animals need sleep so badly in the first place.