A Hadza man sleeps on the ground in northern Tanzania. | David Samson

Trouble Sleeping? Restless Nights Evolved From Ancestors Avoiding Dangers

New research suggests that age-related sleep disorders are maybe not disorders at all but instead are legacies of our evolutionary past, when they were beneficial.

A Hadza hut in Tanzania. Wikimedia Commons
Spotted hyenas eyeing a house cat at night. A. Davey