These days we are used to going to bed at our bedtime and hoping to sleep all night and awaken refreshed in the morning. However, that didn’t used to be the case. In fact, for most of human history, people divided their sleep up into two shorter periods, called “first sleep” and “second sleep.”
Experiment Reveals Humans’ Hidden Sleep Pattern
In the 1990s, a psychiatrist wondered what would happen if people were subject to the long nights typical in a northern hemisphere winter without the influence of artificial lights. He subjected test subjects to a day-night cycle of ten daylight hours and 14 hours of complete blackness. After a couple weeks of adapting, the subjects settled into a definite pattern: the slept for 4 hours, awoke for an hour or two, then went back to sleep for 4 more.
Intrigued, the psychologist started looking at literature from the period before lighting at night was common. He found more than 500 references to this type of sleep pattern in literature, from Homer’s Odyssey to Cervantes’ Don Quixote to Dickens’ Barnaby Rudge. He even found that a tribe of hunter-gatherers in Nigeria still use distinct language to refer to a “first sleep” and “second sleep.”
When It Changed
The sleeping patterns of people began to change when large-scale artificial lighting was introduced. Although people have had artificial light since the invention of fire, maintaining light for nighttime activities remained expensive and difficult for a long time, so most people couldn’t stay up at night and went to bed shortly after dusk.
During the Reformation people began to be more active at night partly out of necessity. People fearing religious persecution often held their religious services at night. (This sometimes backfired, of course, because this type of religious proceedings might be confused with “witches’ sabbaths”).
It wasn’t until the late 17th century that these changes became more widespread, though. In 1667, Paris became the first city to light its streets at night. By 1700, 50 major European cities were lit at night, and the sleep revolution had begun. As people stayed up later in the evening, they tended to lose their mid-night wakeful period, and by the 1920s people had pretty much forgotten about first and second sleep.
Get Quality Sleep When You Sleep
So it’s not necessarily a problem if you feel like waking up for a few hours in the middle of the night, then going back to sleep for the duration of the night. However, it is a problem if you’re waking up regularly, and can’t seem to get quality sleep. If you feel like you’re never getting enough rest no matter how much you sleep, you might be suffering from sleep apnea.