A new study challenges conventional wisdom about how much sleep a person needs each night.
Many people these days aren't getting enough sleep and it's tempting to blame this on well-lit houses with TVs blaring, cell phones buzzing, and a well-used coffee maker in every kitchen. However, researchers from the University of California, Los Angeles found that three ancient groups of hunter-gatherers -- living in different parts of the world without any of those trappings of modern life -- don't get any more sleep, Reuters reported.
"The bigger conclusion is not that they sleep less but that they very clearly do not sleep more, contrary to what has been assumed," UCLA psychiatry professor Jerome Siegel told Reuters.
Those traditional people sleep a little under 6.5 hours a night on average. They don't take regular naps. They don't go to sleep at dark, either. In other words, their sleep habits don't look so different from ours, although they usually do wake up before the sun rises.
"The short sleep in these populations challenges the belief that sleep has been greatly reduced in the 'modern world," Siegel said in a statement. "This has important implications for the idea that we need to take sleeping pills because sleep has been reduced from its 'natural level' by the widespread use of electricity, TV, the Internet, and so on."
For the study, researchers looked at three traditional human hunter-gatherer societies: the Hadza of Tanzania, the San of Namibia, and the Tsimane of Bolivia, PBS reported. The researchers recorded the sleeping habits of 94 individuals around the clock to collect data representing 1,165 days in all.
"Despite varying genetics, histories, and environments, we find that all three groups show a similar sleep organization, suggesting that they express core human sleep patterns, probably characteristic of pre-modern-era Homo sapiens," Siegel says.
Group sleep time averaged between 5.7 and 7.1 hours, with between 6.9 and 8.5 hours between the beginning and end of the sleep period. Those amounts are at the low end of durations reported in "industrial societies."
Hunter-gatherers sleep an hour more in the winter than they do in the summer. Although they lack electric lights, none of the groups went to sleep with the sun. On average, they stayed up a little over three hours after the sun went down and woke up before sunrise.
It appears that their sleep time may have more to do with temperature than with light. Those ancient groups all went to sleep as the temperature fell and slept through the coldest part of the night.
The findings are detailed in the journal Current Biology.
