Why Napping Can't Replace a Good Night's Rest [TheAtlantic.com]
Eight hours of uninterrupted sleep per night—it’s so widely recommended it approaches an axiom. The strange thing is, there’s nothing natural about it. In a landmark 1992 study , Thomas Wehr demonstrated that humans, like many other animals, are naturally inclined to sleep in bouts, separated by periods of activity. Given 10 hours per day of light, instead of the modern sixteen hours of artificial lights-on time, subjects sleep in two symmetrical blocks of several hours each. In the middle...