You probably feel like your sleeping schedule is out of whack in some manner. Either you sleep too much, too little, or wake up too often. In fact, the typical eight hour uninterrupted sleep is what’s really unnatural.
Until about 200 years ago, most people slept as they had for thousands of years. Since there was no bright source of artificial light, people went to sleep when it got dark. They’d naturally wake up during the middle of the night for a few hours. Then they’d go back to bed for what was called the morning sleep.
Researchers re-created conditions for pre-historic sleep in a lab. After a few days of going to bed around 8 p.m., subjects began to experience segmented sleep. They’d wake up around one or two, lie in bed quietly for a few hours, and then fall back asleep. Animals in the wild are known to do this as well.
Our world of artificial light and all-night supermarkets has changed the way we sleep. However, in pre-industrial cultures around the world people still sleep in short bursts instead of through the night.