The Evolution of the Human Sleep Pattern

Humans evolved to have three periods of sleep during atwo approximately four hour chunks at night, with a period of wakefulness between them. That's what the human sleep pattern envolves to be. But now let's get back in the tartis and see what people in the modern, developed world are doing. In some countries it's still normal to take a nap or a siesta after lunch, but in places like the united states there is no time allotted for napping.