If we could only get back to ancient times when our lives were spent hunting deer, picking berries and snuggling up with furs at sunset, we might finally get a decent night’s sleep.
At least that is how the argument goes. But according to new research, modern life has done nothing to rob us of sleep, despite the invention of the electric lightbulb, the TV, the internet, smartphones and social media.
Scientists who studied three hunter-gatherer and hunter-horticulturalist societies in Africa and Bolivia found that they stayed up for hours after sunset and got no more sleep than people in the industrialised world. None had access to electricity and their only source of light after dark was a campfire.
The findings, reported in the journal Current Biology, suggest that our sleep patterns today are not overly different to those of our ancient ancestors, and that we might be obsessing unnecessarily about how much sleep we get.
“People are always saying we sleep a lot less than we used to and that it started with the electric light. They argue that we are really meant to be asleep when it’s dark,” said Jerome Siegel, professor of psychiatry at the University of California in Los Angeles. “But how can that be based on hard data? We’ve only been able to measure sleep properly for the past 50 years.”
More than 100 years ago, in 1894, the British Medical Journal ran an editorial which raised concerns about sleep loss and urged readers to live more quietly. “The pity of it is that so many people are unable to follow this good advice and are obliged to lead a life of anxiety and high tension,” it said.
Unable to travel back in time to monitor the sleeping habits of our paleolithic ancestors, Siegel worked with three groups of people who live life much as our forebears did for millennia. He asked members of the Hadza in Tanzania, the San in Namibia and the Tsimane in Bolivia to wear watches that recorded their sleep. In total 94 people in total were tracked for six to 28 days each throughout the seasons, creating sleep data for 1,165 separate days.
He found that none of the groups went to sleep at sundown, and instead stayed up for an average of three hours and 20 minutes longer. “They are up for a good two hours after it is as dark is it ever gets,” Siegel said.
Nor did the people sleep that long. A typical night’s rest amounted to six hours and 25 minutes, at the low end of sleep times recorded for people in Europe and the US. They slept an hour longer in the winter than in the summer.
“There’s this expectation that we should all be sleeping eight or nine hours a night and that if you took away modern technology, people would be sleeping more,” said Gandhi Yetish, a co-author on the study at the University of New Mexico. “We’re showing that’s not true.”
But Siegel believes that the groups’ sleep patterns were connected to natural cycles. All went to sleep as the temperature was falling and woke when it reached its minimum, at around sunrise. He hopes now to test whether going to sleep in a room that gets steadily cooler helps people who struggle to get to sleep.
Siegel points out that his work addresses a serious medical problem. Having unrealistic expectations of sleep can be dangerous, he said. “If you go to your GP and say doctor I really think I should sleep more, they’ll give you whatever the last sleeping pill rep who was in their office was handing out.”
Several studies have linked the chronic use of sleeping pills to a shorter life, but the pills might not be to blame. It may be that people with underlying health problems sleep worse and so take more sleeping pills. But even so, Siegel points to the massive use of sleeping medicines in the US, where in 2008, pharmacists wrote out 56 million prescriptions for the pills.
Prof Derk-Jan Dijk, director of the Surrey Sleep Research Centre, said: “If we don’t have access to electricity and only have campfires for light we tend to wake up before or close to sunrise, and that makes sense, but when we get electricity, that changes. We can turn a light on and go long into the night. There are still many people in our society who do not get enough sleep, who find it difficult to get out of bed in the morning.”
In 2013, Dijk found that getting too little sleep for several nights disrupted the activity of more than 700 genes involved in the immune system, metabolism and the body’s responses to stress, though how long the changes last for is not known.
“We shouldn’t forget that there are real sleep problems out there. There are people with insomnia, and these people cannot get to sleep even though they have the opportunity to. They deserve treatment, though whether that should be pharmacological or not is an important area of research,” he added.
