Candles and artificial lights used to be expensive. When it got dark you couldn't work without light. Naturally you fell asleep. But what happens when the night lasts longer than the 8 or 9 hours that we need for sleep? You either wake up while it's still dark, or you take a break from sleep in the middle of the night. Your body has a memory not just when you went to sleep, but somehow of your whole sleeping cycle. Once you start waking up in the middle of the night for a few hours, that becomes your need sleep schedule.
Candles and artificial lights used to be expensive. When it got dark you couldn't work without light. Naturally you fell asleep.
But what happens when the night lasts longer than the 8 or 9 hours that we need for sleep? You either wake up while it's still dark, or you take a break from sleep in the middle of the night. Your body has a memory not just when you went to sleep, but somehow of your whole sleeping cycle. Once you start waking up in the middle of the night for a few hours, that becomes your need sleep schedule.
People used lanterns. Cows got to be milked and looked after during birth.
People used lanterns. Cows got to be milked and looked after during birth.
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