Ok, maybe your grandparents probably slept like you. And your great, great-grandparents. But once you go back before the 1800s, sleep starts to look a lot different. Your ancestors slept in a way that modern sleepers would find bizarre – they slept twice.

The existence of our sleeping twice per night was first uncovered by Roger Ekirch, professor of History at Virginia Tech. His research found that we didn’t always sleep in one eight hour chunk. We used to sleep in two shorter periods, over a longer range of night.

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