What Did Ancient Humans Do at 3 AM?

You wake at 3AM and call it insomnia. For most of human history it was just the middle of the night. Two bodies of evidence disagree: five hundred references to "first sleep" and "second sleep" in pre-industrial documents, and wrist monitors on three communities living today without electric light, which found no split sleep at all. The answer is temperature, and who you were lying next to. Plus the number of minutes all thirty-three Hadza adults were asleep at once. This is a general explainer, not medical advice. CHAPTERS 0:00 Why You Wake Up at 3AM 0:57 First Sleep and Second Sleep 2:17 The Dark Room Experiment 3:08 What Ancient Humans Did When They Couldn't Sleep 3:57 The Twist: Only Europe? 4:23 Hunter Gatherer Sleep, Actually Measured 4:48 It Was Temperature, Not Darkness 5:30 Somebody Was Always Awake 6:07 Why Did Ancient Humans Sleep In Groups 6:37 How Did Ancient Humans Sleep Without Beds 7:34 Your Night, Compared 8:23 What To Do Tonight SOURCES Roger Ekirch, At Day's Close: Night in Times Past (Norton, 2005); and "Sleep We Have Lost: Pre-industrial Slumber in the British Isles", American Historical Review 106:2 (2001), 343-386. Thomas A. Wehr, "In short photoperiods, human sleep is biphasic", Journal of Sleep Research 1:2 (1992), 103-107. Lyn Wadley et al., "Middle Stone Age Bedding Construction and Settlement Patterns at Sibudu, South Africa", Science 334:6061 (2011), 1388-1391. Gandhi Yetish et al., "Natural Sleep and Its Seasonal Variations in Three Pre-industrial Societies", Current Biology 25:21 (2015), 2862-2868. David R. Samson et al., "Chronotype variation drives night-time sentinel-like behaviour in hunter-gatherers", Proceedings of the Royal Society B 284 (2017), 20170967. Sinew: one question per film about ordinary life in the deep past. #ancienthumans #earlyhumans #sleepscience