> [so] that a group of people could watch the village 24/7 Matthew Walker alludes to this in his book on sleep; however, in his description it's not so much ol

> [so] that a group of people could watch the village 24/7 Matthew Walker alludes to this in his book on sleep; however, in his description it's not so much older vs younger people, it's just genetic differences that make some people sleep earlier and some later, with a fairly stable 60/40 or so distribution. Thus, the "dangerous" period (where everyone sleeps) gets reduced from 8 hours to, say, 3 hours.