Temperature and social time: How hunter-gatherers ensure they get a good night's sleep

Hunter-gatherer communities are a window on how the human species learned to get a good night's rest. Here's what you can learn from them.

When it comes to how our hunter-gatherer ancestors slept, there's a lot that we don't know. There's also some long-lasting assumptions, including the belief that they slept from dusk to dawn, that have recently been largely discredited.

But research on today's foraging societies, often considered the best evidence we have for how we may have slept for more than 95% of human evolutionary history, has revealed a consistent finding: in general, people in foraging societies rarely report sleep problems.

"If you ask hunter-gatherers, 'Do you ever have trouble sleeping?' in their native language, they have trouble understanding the concept," says University of California, Los Angeles sleep scientist Jerome Siegel, who has studied the sleep patterns of Tanzania's Hadza, Bolivia's Tsimane and Namibia's San communities. That's even though the people who have been studied in non-industrial societies generally sleep less, and wake more, than those of us in industrialised ones.

So what's their secret? Over the course of my reporting for my book The Sleep Myth and the BBC newsletter How to Sleep Better, I discovered some of the methods, approaches and ways of thinking that may have helped our ancient ancestors get their zzzs – and that the rest of us could incorporate to sleep a little bit better, too. Here are five of the most effective.

Get light exposure during the day

Even if some aspects of our sleep quantity and quality are better, on average, in industrialised societies, one of the main foundations of sleep is not. And that's our circadian rhythms, the biological "clocks" that signal to our bodies when it's time to be awake and when to be sleepy – and which need consistent inputs from different cues called "zeitgebers" to stay on track.

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"We're living in environments that dysregulate this ancient timing system," says David Samson, director of the University of Toronto's Sleep and Human Evolution Lab and author of the book The Sleepless Ape: The Story of Sleep in Human Evolution.

The primary zeitgeber – meaning "time giver" – is light, which is why researchers suggest that, as soon as you can after waking, you get any exposure that you can. Importantly, for those of us in industrialised societies, that doesn't just help keep our circadian rhythms on track. It may also blunt the effect of using artificial light at night (which, for what it's worth, might also not be quite as bad for us as we thought).

Researchers have found that while using a very bright screen for several hours before bedtime might delay sleep onset by about 10 minutes, that effect disappeared if participants also experienced bright light exposure during the day.

Of course, this can be hard in darker climes, or for those of us who work indoors. But small spells might help, so the next time you have the option to walk a few extra minutes instead of take the train, eat lunch outside instead of indoors, or work at a desk under a window, take it.

Keep time with........

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