Turn Off the Lights!
Sleep researcher Roger Ekirch’s work on changing sleep patterns in man led him to a discovery that surprised him: the biggest shift came with electricity and artificial light. In the “preelectric” centuries, people slept differently. We assume it is normal to slumber more or less continuously through the night. We think of wakefulness as a sleeping problem or disorder – insomnia. Common sense suggests that, without electric lights, our preindustrial ancestors must have slept from sunset to sunrise. But Ekirch has found that was not so.
Preindustrial people’s sleep was segmented. They might lie an hour or more before falling asleep. About four hours later, they would awaken. For another hour or so, they would lie meditating on their dreams or praying. they would talk with bedmates. They might even visit neighbors, similarly awake. They might pilfer or poach. Then they would sleep another four hours or so. People, as a matter of course routinely referred to their “first sleep” and their “second sleep”. Ekirch traded information with a National Institute of Mental Health psychiatrist, Thomas H. Wehr, studying sleep patterns among volunteers. Deprived of artificial light these modern people reverted to the preindustrial pattern: sleeping a while, lying awake for one to three hours, then sleeping again. Wehr believes he may have found a reason. Without the stimulus of artificial light, people secrete more prolactin, a pituitary hormone that seems to promote a state of quiet restfulness. That hormone is best known, “for permitting chickens to brood contentedly atop eggs for long stretches of time.” The study indicates that most preindustrial people slept differently because they had less artificial light recalibrating their hormone production.
Luckily now, people have natural sleep aids to help induce a long and peaceful night’s sleep.