Waking Up at 3AM Used to Be Normal

If you wake in the middle of the night and lie there doing arithmetic about how many hours you have left, this video is about you. For most of recorded history, that waking was not a symptom. It was the schedule. People slept for about four hours, got up for an hour or two, then slept again until morning. The two halves had names — first sleep and second sleep — and nobody bothered to explain them, because everyone knew what they meant. This video covers how a historian stumbled onto that pattern while researching something else, what a sleep experiment in the 1990s found when it gave volunteers fourteen hours of darkness, and what killed the second sleep: gas lamps, electric light, and a working day that started at a time instead of at dawn. It also covers the part usually left out. In 2015, researchers measured sleep in three societies living without electric light and did not find the pattern at all. So the honest answer is narrower than the popular version, and this video says where the line is. #sleep #history #science #insomnia #documentary