Do we really heed 8 hours of sleep and a nap?
In a study published in Current Biology this week, researchers traveled to remote corners of the planet to scrutinize the sleep patterns of some of the world's last remaining hunter-gatherers — the Hadza of Tanzania, the San of Namibia, and the Tsimane of Bolivia. Cut off from electricity, media and other distractions, these pre-industrial societies are thought to experience the same sort of natural sleep ancient humans enjoyed more than 10,000 years ago...
What they found was a striking uniformity in their sleep patterns despite their geographic isolation. On average, all three groups sleep a little less than 6.5 hours a night, do not take naps and don't go to sleep when it gets dark. Like many of us, the Hazda, San and Tsimane spent more than that in bed — from 6.9 to 8.5 hours than actually sleeping. That computes to a sleep efficiency of between 81 to 86 percent — which is very similar to today's industrial populations.
A full report is at WaPo.