What Did Ancient Humans Do After Dark?

It's 3:47 in the morning, and you're awake again. You've probably heard the explanation: our ancestors slept in "two shifts," and waking at night is just your body remembering. But when scientists put sleep trackers on people who still live without electricity, that's not what they found. They found something stranger: in one camp, over twenty nights, there were only 18 minutes when every adult was asleep at the same time. In this video we discuss: • Why a 2-million-year-old skull with two small holes changes how we see the night • Why a campfire was only as safe as the person feeding it • The 18 minutes: what sleep trackers revealed about who stayed awake, and why • The "poorly sleeping grandparent" idea, and what it says about teenagers who can't fall asleep • What the night watch actually did around the fire, and on bright moonlit nights Stay to the end to find out why waking at 3:47 might not mean anything is wrong with you at all. A note on the evidence: the sleep studies in this video measured modern groups who live without electricity (the Hadza, San and Tsimane). They are the closest model we have, not a direct record of prehistoric life. 🛑 WATCH NEXT: A Day in the Stone Age 👉    • A Day in the Stone Age   🔹 Chapters: 00:00 Awake at 3:47 00:50 What Waited Outside the Camp 01:49 You're Asleep. Your Grandmother Isn't. 02:17 The Eighteen Minutes 03:10 What the Night Watch Did 04:02 The Guard at 3:47 📚 Sources: Samson, D. R. et al. (2017). Sentinel hypothesis: chronotype variability in Hadza hunter-gatherers. Proceedings of the Royal Society B. Yetish, G. et al. (2015). Natural sleep and its seasonal variations in three pre-industrial societies. Current Biology. Brain, C. K. (1970). New finds at the Swartkrans australopithecine site (SK 54). Nature. Berna, F. et al. (2012). Microstratigraphic evidence of in situ fire in the Acheulean strata of Wonderwerk Cave. PNAS. Wiessner, P. (2014). Embers of society: Firelight talk among the Ju/'hoansi Bushmen. PNAS. Casiraghi, L. et al. (2021). Moonstruck sleep: Synchronization of human sleep with the moon cycle under field conditions. Science Advances. #ancienthumans #stoneage #prehistory #sleep #history #beforeelectricity