Or dance to sleep

You know, this is a good question.

Googling it would ruin the fun, but I’d assume that it’s an evolutionary thing so you don’t decide to go to sleep in an unsafe situation and get yourself eaten.

A related question might be, are there people who can deliberately make themselves sleep? For example, those that can close their eyes and just sleep in seconds. Are they falling asleep, but just faster than most, or do they decide to sleep?