And the Power!
At this point I can't remember what book because I'm reading like three to four at the same time but there was this one book that had a bit about how not everyone has the same sleep schedule. Some of us are morning people and some of us are not. The point being that if you can get a job or live your life around your internal clock you tend to be happier and more productive. One genius would sleep a few hours, get up do stuff, go to sleep again, etc. He never actually had a night and day, just spaces of time when he would either be awake or asleep.