Foraging societies offer a rare view into sleep patterns that may have shaped humans through more than 95% of evolutionary history. Their habits also challenge the enduring assumption that our ancestors routinely slept without interruption from dusk until dawn.

Research involving Tanzania's Hadza, Bolivia's Tsimane and Namibia's San communities has produced a strikingly consistent observation. People in foraging societies rarely report having difficulty sleeping, even though they generally sleep less and awaken more often than people in industrialised societies.

University of California, Los Angeles sleep scientist Jerome Siegel has studied all three communities. “If you ask hunter-gatherers, 'Do you ever have trouble sleeping?' in their native language, they have trouble understanding the concept,” he says.

Some measures of sleep quantity and quality may be better on average in industrialised societies. Yet modern environments can disrupt circadian rhythms, the biological clocks that tell the body when to be alert and when to become sleepy.

Circadian rhythms depend upon consistent environmental signals known as zeitgebers, meaning time givers. David Samson, director of the University of Toronto's Sleep and Human Evolution Lab, says, “We're living in environments that dysregulate this ancient timing system.”

Light is the primary zeitgeber, which is why researchers recommend getting exposure as soon as possible after waking. For people in industrialised societies, daytime light may also reduce the influence of artificial illumination used during the evening.

In one study, using a very bright screen for several hours before bedtime delayed sleep onset by about 10 minutes. That effect disappeared when participants also received bright light exposure during the day.

Getting sufficient daytime light can be difficult for people who work indoors or live in darker climates. Even short periods may help, whether someone walks outdoors for several minutes, eats lunch outside or works beside a window.

Temperature is another environmental cue that may influence sleep. Even in hot climates, temperatures generally decline through the night before rising again during the day.

Siegel considers temperature an underappreciated signal. Groups such as the Hadza usually fall asleep several hours after sunset and awaken before sunrise, with their sleeping schedules following temperature more closely than light.

Many people in industrialised societies live in homes that remain at roughly the same temperature throughout the day and night. Siegel suggests lowering the thermostat by a few degrees before bed, programming it to fall overnight or opening a window.

Seasonal changes also affect sleep among foraging communities. People tend to sleep less when days are longer and warmer, then sleep more when days become shorter and colder.

Many members of these societies awaken at a similar time each day, which can help reset circadian rhythms. At the same time, their seasonal patterns suggest people should not necessarily worry when sleep schedules and durations shift throughout the year.

Evenings in foraging communities do not begin with everyone immediately going to bed. People instead gather around fires, tell stories and visit one another, creating a clear separation between practical daytime responsibilities and quieter nighttime activities.

Anthropologist Alyssa Crittenden of the University of Nevada, Las Vegas, has spent time with the Hadza each year for two decades. She describes the evening as “radically different” from daylight hours dominated by discussions about logistics, childcare and food.

These nighttime activities are also communal, helping build feelings of cohesion and support. Crittenden calls this pattern the “nighttime cooperative niche,” and the communal atmosphere can continue as people share rooms or sleeping surfaces with partners, children, friends or neighbours.

Evidence from industrialised societies also suggests that people may feel they slept better beside someone else than when sleeping alone. Decades of research finding that loneliness is associated with worse sleep raise the possibility that evening social connection may be helpful.

Researchers repeatedly found that people in foraging and other nonindustrial societies sleep less and awaken more than people in industrialised countries. Crittenden says the pursuit of eight uninterrupted hours means people “are trying to get at something that is, physiologically, a fantasy”.

Anxiety about reaching that ideal may itself make sleep worse. Evolutionary anthropologist Gandhi Yetish advises, “Don't expect your sleep to look the same every single night.”

Yetish notes that society expects people to perform at the same optimal standard each day, encouraging them to seek identical sleep every night. Accepting natural variation means recognising that energy, focus and sharpness will not always remain constant.

Persistent insomnia or exhaustion should not be dismissed, and anyone concerned about a sleep or other health problem should see a clinician. Yet ordinary variation is part of being human, and accepting it may paradoxically become an important step toward sleeping better.