Michael Ende

It is only when you watch the dense mass of thousands of ants, crowded together around the Hill, blackening the ground, that you begin to see the whole beast, and now you observe it thinking, planning, calculating. It is an intelligence, a kind of live computer, with crawling bits for its wits.

If you think about evolution, sleep, at some time, was a dangerous undertaking. You lie down in your cave or shelter, and along comes a predator and has you for dinner. Many creatures do not sleep or sleep while standing so they can escape from dangerous situations.