It sure doesn’t feel like it, but Scientific American has some research to suggest that all these screens and electric lights really aren’t ruining our primal, natural-born sleep schedules… as much as the A/C is:
The researchers looked at people living in three hunter-gatherer societies in rural parts of Africa and South America. Investigations showed that these traditional peoples slept slightly less than 6.5 hours a night on average. In comparison, people in industrial societies usually average seven to eight hours per night.
“We find that contrary to much conventional wisdom, it is very likely that we do not sleep less than our distant ancestors,” said the study’s senior author, Jerome Siegel, a sleep researcher at the University of California, Los Angeles.
However, the researchers also found that insomnia may have been more rare in ancient times than it is now. This finding suggests that looking to the past could lead to new ways of treating insomnia, which afflicts more than 20 percent of people in the United States at some point during their lives, the investigators added.
To learn more about how people slept before the modern era, the researchers analyzed the sleeping habits of 94 members of three hunter-gatherer societies: the Hadza of Tanzania, the San of Namibia and the Tsimane of Bolivia. These people live much as their ancestors did for thousands of years, so the scientists reasoned that these people’s sleep habits reflect prehistoric human behavior.
After collecting 1,165 days’ worth of data on these hunter-gatherers, the scientists found a surprising similarity across the three groups. Despite differences in their genetics, histories and environments, all three groups had similar sleep patterns, which the researchers suggested mirrored those of humans before the modern era.
“I feel a lot less insecure about my own sleep habits after having found the trends we see here,” study lead author Gandhi Yetish at the University of New Mexico said in a statement.
For example, none of these groups went to sleep as soon as it got dark, much like industrial people do. Instead, the hunter-gatherers began to sleep a little more than 3 hours after sunset, on average. Nighttime activities included preparing food, eating dinner, making arrows and planning for the next day, Siegel said.
However, the scientists uncovered one big difference between these groups and people who live in industrial societies: Only 1.5 to 2.5 percent of the hunter-gatherers the researchers studied experienced insomnia more than once a year. In comparison, 10 to 30 percent of people in industrial societies report chronic insomnia, the scientists noted. Insomnia was so rare among the San and the Tsimane, they do not have a word for the disorder.
The scientists found that the amount of sleep these hunter-gatherers got had less to do with the length of daylight hours than with temperature. These groups sleep an hour more in the winter than they do in the summer.
“In natural conditions, humans sleep [more] during a period of declining temperature,” Siegel said. “In contrast, in most modern settings, while we may turn the temperature down at night, it is not declining.”
In other words, modern life has “almost completely eliminated a major sleep regulator,” he said.
(By the way, I’d love to see the grant application: “We’re taking some Land Rovers out into the Kalahari to watch San people sleep.”)