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.

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.

"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.

Another environmental input that could help with our sleep? Temperature – which, even in hot climates, tends to fall over the course of the night and rise again during the day.

Scientists like Siegel think it may be an especially underrated one, pointing to how non-industrial groups like the Hadza tend to go to sleep a few hours after sunset and wake before sunrise, with their timings tracking temperature, not light.

In industrialised societies, many of us live in homes where the temperature stays the same, day and night. To get some of the effect, he says, try turning the thermostat down a few degrees before bed, setting a smart thermostat to fall over the course of the night, or opening a window.

And yes: both light and temperature change over the course of the year – and the sleep of hunter-gatherers changes with them. That's not just in terms of timings, but also sleep durations, with people sleeping less when days are longer and warmer, and more when they're shorter and colder.

So, while many people in these societies tend to wake up around the same time each day (and that's another way that we can help re-entrain our circadian rhythms), not worrying about our sleep shifting with the seasons is important, too.

When evening sets in in foraging societies, people don't immediately go to bed, researchers told me. They engage in relaxing, non-work-centred activities – whether gathering around campfires, telling stories, or visiting each other.

"The moment the Sun goes down, everything starts getting quiet," says anthropologist Alyssa Crittenden at the University of Nevada, Las Vegas, who has spent time with Tanzania's Hadza each year for two decades. "During the day, most activity and conversations revolve around really practical matters. They revolve around logistics, they revolve around childcare, they revolve around food… But at night, you're done with that."

The fact that the evening is "radically different" from the more work-oriented daylight hours is "extremely important," she adds – and one more signal to our bodies, and brains, that it's time for sleep. It's yet another reason, for those who are able, to kick the habit of checking work emails or paying bills right before bed – and for leaders in the workplace to stop expecting employees to do so, too.

You might have noticed that the night-time activities foraging groups engage in aren't just non-work-related, but communal. That's no mistake, says Crittenden; they build a sense of cohesion and support. She's even given it a name: the "nighttime cooperative niche".

Many people in these societies sleep in the same room, or on the same surface, as others – not just their intimate partners, but their children, and in some cases friends or neighbours – that sense of communality continues even while they sleep, too. Even in industrialised societies, there is some evidence that we may feel like we slept better when we sleep with someone else than when we sleep alone.

With several decades of research finding that people who feel lonely sleep worse, it's possible that these sorts of activities aren't just good for social cohesion, but that feeling connected is good for our sleep.

For those of us who live in smaller units, like nuclear families, or alone, incorporating that kind of sociality into an evening routine can be harder to attain. But it's a reminder that partaking in evening activities with others, whether a group yoga class, having friends over for dinner, or a catch-up phone call, might be a big help.

Again and again, researchers told me the same thing: on average, people in foraging and other non-industrial societies sleep less and wake more than we do. Those of us in industrialised countries, with our aims for eight uninterrupted hours, "are trying to get at something that is, physiologically, a fantasy", as Crittenden puts it. By increasing our anxiety around sleep, this goal might actually be making us sleep worse.

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In a society increasingly obsessed with optimising and quantifying every element of our wellbeing, including our sleep, many of us might benefit from accepting the idea that not every night will look exactly the same – nor does it necessarily have to for us to function.

"Don't expect your sleep to look the same every single night," says evolutionary anthropologist Gandhi Yetish, lead author of the paper on the Hadza, Tsimane and San and other research on hunter-gatherer sleep. "You wouldn't eat the exact same thing two days in a row. Why would you expect to sleep exactly the same way two days in a row?"

Of course, he notes, part of the problem is that we are expected to perform to the same, optimal standard every day – so it makes sense that we expect to get the same, optimal level of sleep each night, too. But perhaps that, more than anything else, is the mindset that we need to adjust.

We will have days where we feel a little more or less energised, focused or sharp. Sometimes, that can indicate a sleep (or other health) problem – and it's important to see a clinician if you're concerned; chronic insomnia, or exhaustion, should never be dismissed. But some degree of variation is just because we're humans, not machines. And embracing that fact might, paradoxically, be an important part of sleeping better. 

* Amanda Ruggeri is a science, psychology and history journalist. She writes the six-part How to Sleep Better newsletter course, and her forthcoming book, The Sleep Myth, will be published in summer 2027.

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