The Atlantic dives deeply into the recent study that found hunter-gatherers don’t get more sleep than we do.

Horacio de la Iglesia from the University of Washington disagrees that these short sleep durations are a “signature of human ancestral sleep,” noting that some other hunter-gatherer communities sleep for up to 9 hours. And “there is plenty of evidence that industrialization has indeed reduced sleep,” he adds. In one of his own studies, a group of Argentinian hunter-gatherers with access to electric lights got an hour less sleep every day than a neighboring community that relied only on natural lighting. (By contrast, Siegel’s study lacked a similar control group.)