>But humans have never had a universal method of slumber. A 2015 study of hunter-gatherer societies in Tanzania, Namibia, and Bolivia found that most foragers enjoyed one long sleep. Two years later, another study found that a rural society in Madagascar practiced segmented sleep. Two years after that, a study found that the indigenous residents of Tanna, in the South Pacific, largely had one uninterrupted sleep.
https://www.sciencealert.com/humans-used-to-sleep-in-two-shi... https://www.discovermagazine.com/health/dont-worry-if-you-ca...
However, I did find this article from The Atlantic: https://archive.is/MYcgm#selection-1033.0-1049.105
>But humans have never had a universal method of slumber. A 2015 study of hunter-gatherer societies in Tanzania, Namibia, and Bolivia found that most foragers enjoyed one long sleep. Two years later, another study found that a rural society in Madagascar practiced segmented sleep. Two years after that, a study found that the indigenous residents of Tanna, in the South Pacific, largely had one uninterrupted sleep.