David K. Randall:
The idea that we should sleep in eight-hour chunks is relatively recent. The world’s population sleeps in various and surprising ways. Millions of Chinese workers continue to put their heads on their desks for a nap of an hour or so after lunch, for example, and daytime napping is common from India to Spain.
I’ve always found the 8 hour thing a bit weird. Turns out, it is a bit weird.