A sleep scientist who has dedicated much of his career to studying the slumber patterns of Earth's remaining contactable hunter-gatherer communities recently shared his findings with the BBC, and the results challenge common assumptions about what constitutes healthy rest.
Jerome Siegel, a somnologist at UCLA, examined sleep behaviors among the Tsimane in Bolivia, the San in the Kalahari, and the Hadza in Tanzania. His research suggests that these communities possess a fundamentally different relationship with sleep than people in industrialized nations.
"If you ask hunter-gatherers, 'do you ever have trouble sleeping?' in their native language, they have trouble understanding the concept," Siegel told the BBC.
The evolutionary perspective offers context for this disparity. Sleep has been preserved across virtually every life form observed, from ancient bacteria to the most complex animals. According to principles of natural selection, characteristics that could be eliminated without consequence would eventually disappear. The fact that sleep persists throughout organic life suggests it serves an essential function.
The BBC article was compiled by Amanda Ruggeri, a journalist specializing in science, psychology, and history. Her book, The Sleep Myth, is scheduled for release in 2027.
Light exposure plays a significant role in regulating hunter-gatherer sleep cycles. Artificial light is known to delay sleep onset, disrupting the body's internal clocks, which are called circadian rhythms. To align these rhythms more naturally, Siegel's research suggests obtaining natural light immediately upon waking. Practical approaches include drinking morning coffee outdoors or positioning oneself near an east-facing window. In the evening, keeping the home as dark as safety permits, turning off unnecessary lights, using dimmers, and limiting screen time can support better sleep.
Temperature represents another critical variable. According to Siegel, the pattern of declining temperatures at night and rising temperatures in the morning aligns more closely with sleep schedules in non-industrialized communities than light does. These groups frequently wake several hours before sunrise, when sleep-time temperatures reach their lowest point. To mimic this pattern, individuals might open windows, program thermostats to decrease hourly, or arrange for cooler temperatures in the pre-dawn hours.
Social interaction also shapes sleep habits in these communities. Another sleep researcher informed Ruggeri that hunter-gatherers typically participate in social activities at sundown and after dark. In the absence of light and electricity, productive work becomes impossible, so attention shifts entirely to socializing. Replicating this aspect involves spending time with family or friends. The more challenging component is resisting the compulsion to check work email and refraining from expecting employees to do the same.
Despite their unfamiliarity with the concept of sleep difficulties, hunter-gatherers actually sleep less and wake more frequently than people in modern, technologized societies. The crucial difference is that for them, this pattern is normal and not a source of stress. One of Siegel's colleagues told the BBC that in modern societies, "good" sleep has become defined as the pursuit of eight uniform, uninterrupted hours—a standard that represents a comparative fantasy when measured against the sleep patterns of hunter-gatherers.
This leads to a fourth consideration: accepting that sleep will not be identical every night. Releasing anxiety about waking during the night or sleeping less than desired may actually improve morning alertness and make falling asleep easier the following evening.
