Age-related differences in sleep patterns can guarantee that at least one person is awake at night in case of danger, according to the findings of a new study of modern hunter-gatherers in northern Tanzania still living in groups.
The hunter-gatherers in the study live and sleep in groups of 20 to 30 people and follow day and night cycles as humans did for hundreds of thousands years before the development of agriculture.
Study co-author Charlie Nunn, a professor of evolutionary anthropology at Duke University, says: “A lot of older people go to doctors complaining that they wake up early and can’t get back to sleep. But maybe there’s nothing wrong with them. Maybe some of the medical issues we have today could be explained not as disorders, but as a relic of an evolutionary past in which they were beneficial.”