Our Ancestors Didn’t Get 8 Hours of Sleep Either

Photo: 2/Asia Images/Corbis

You would get so much more sleep if not for the modern evils of electricity, TV, and the internet, right? Maybe not. Researchers at UCLA and the University of New Mexico suspect our ancestors didn’t sleep any better than we do. In order to investigate this claim without a time machine, they put medical-grade sleep trackers on the wrists of people in three hunter-gatherer communities who are thought to experience the same “natural” sleep of our forebears. Turns out they don’t get any more sleep than modern city dwellers. In fact, they get a little less.

For a study published in Current Biology, the team looked at 1,165 nights’ of sleep data from 94 adult members of the Hadza people of Tanzania, San people of Namibia, and Tsimané people of Bolivia. They found that mean sleep time was 6.4 hours, or 6 hours 25 minutes per night, which is slightly less than the average American. Sleep time ranged from 5.7 to 7.1 hours among the groups. Mind you, that’s actual snoozing time; they were in bed for longer than that, spending an average of 6.9 to 8.5 hours in repose. And before you ask, despite a lack of modern medicine, these people’s lifespans are much better than our ancestors’: They often live well past the age of 60 and even into their 70s and 80s.

Sleep deprivation has been linked to obesity, mental-health problems, and other chronic diseases, and in June, the American Academy of Sleep Medicine issued recommendations saying adults should get 7 or more hours of sleep on a regular basis. But the president of the AASM told the New York Times that most studies on the topic rely on self-reported sleep data and it’s very possible that people overestimate the amount of ZZZs they’re getting by saying how long they’re in bed, which is different from how long they’re actually conked out. 

But sleep is, after all, pretty personal. Some people can feel totally refreshed on six hours while others really need eight to function. The study authors worry that presenting a number as the “ideal” or required amount of sleep could lead people to take sleeping pills they don’t really need. So maybe don’t try to get by on four or five hours per night, but if you’re “only” getting six and a half and you feel good, it’s probably not worth stressing over.

Our Ancestors Didn’t Get 8 Hours of Sleep Either