Hunter-gatherer communities are a window on how the human species learned to get a good night's rest. 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. 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. 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 [anthropologist Alyssa] Crittenden; they build a sense of cohesion and support. She's even given it a name: the "nighttime cooperative niche".