Why sleeping alone may be keeping you up at night

You’ve heard the rules for being rested: Get 7 to 8 hours of sleep, limit caffeine, have a bedtime routine, turn off your devices. But many still struggle. The Centers for Disease Control says that more than 50 million American adults have a sleep disorder. A new book about the history of sleep found that two centuries ago, things were completely different. Sleep was social, and people dozed in two 4-hour chunks rather than a straight 8-hour shot through the night.

Benjamin Reiss is author of the new book “Wild Nights: How Taming Sleep Created Our Restless World.” (Photo by Gretchen Connell)