You definitely see a bit of this in other primates. They sleep on trees (much safer) and for a lot more hours than humans.

That's great for primates, but what about nematodes? Everything with a nervous system sleeps, even when the cost is high.

	▲	redox99 29 minutes ago \| parent [-]
		Obviously sleep is necessary. I'm saying that there isn't always a large pressure to minimize sleep. Long sleep can be beneficial just to preserve energy.