You don’t need eight straight hours of sleep. You need three extra hours in the day.

You Don’t Need Eight Straight Hours of Sleep—Just Three Extra Hours in the Day

You Don’t Need Eight Straight Hours of Sleep—Just Three Extra Hours in the Day

The Drift
A blog about sleep.
Nov. 12 2015 9:30 AM

The Eight-Hour Sleep Session Is Not What You Need

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Photo by Matelly/Getty Images, with additional illustration by Lisa Larson-Walker

We know how much sleep we need: eight hours. But isn’t there something suspiciously neat about that figure? Eight, after all, is a third of 24, the number of hours God chose to include in a diurnal cycle. The eight-hour day was the great victory of the labor movement. “Eight hours’ labour, eight hours’ recreation, eight hours’ rest,” as the Welsh socialist Robert Owen had it—a third of the day for our bosses, a third for our bodies, and the remaining third for ourselves. Can it be that our biological needs align so precisely with our political achievements and with the rotation of the spheres? 

Gabriel Roth Gabriel Roth

Gabriel Roth is a Slate senior editor and the editorial director of Slate Plus. Follow him on Twitter

Nah. The eight-hour sleep session, it turns out, is as much a creation of modernity as the eight-hour workday. Evidence from both history and psychology suggests that eight consecutive hours of sleep—the great unattainable dream of every anxious office worker and overburdened parent—is itself an uncomfortable compromise that crams our physiological requirements into a tiny container, suffocating an essential part of our humanity in the process. 

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The historian A. Roger Ekirch has uncovered a pattern of references to “first sleep” and “second sleep,” or “morning sleep,” in sources from Homer and Plutarch to John Locke. Until the spread of artificial light in the 18th and 19th centuries, it turns out, our ancestors slept in two shifts of roughly four hours each, with a period of wakefulness in between. That interval was a peaceful time, a time for contemplation and reflection and maybe copulation. “Usually, people would retire between 9 and 10 o’clock only to stir past midnight to smoke a pipe, brew a tub of ale or even converse with a neighbor,” Ekirch wrote. “Others remained in bed to pray or make love.” 

The scientific evidence suggests that our biology is better adapted to what’s often called “segmented sleep” than to our own efficiently consolidated slumber. In the early 1990s, the psychobiologist Thomas Wehr tried depriving test subjects of light for 14 hours a day, then allowed them to sleep for as long as they liked. He found that “their sleep episodes expanded and usually divided into two symmetrical bouts, several hours in duration, with a 1-3 h waking interval between them.” During that interval, Wehr’s subjects achieved a state of unusual serenity, which he attributed to elevated levels of prolactin, the pituitary hormone associated with breastfeeding and sexual afterglow. 

In other words, there is a natural sleep rhythm that we have largely abandoned, one that sustained our ancestors for millennia, and it includes a gently blissful opportunity for reflection or meditation or prayer or sexual intercourse, and all you have to do to achieve it is to set aside an additional two or three hours of every day. 

Clark Strand, the author of Waking Up to the Dark, calls on us to recognize the value of that nighttime interval of wakefulness: “an hour in the middle of the night where peace was there for the having ... a nightly blessing.” 

“I’ve been following this sleep pattern since I was a young child,” Strand told me. “I lived down South where there was a little less light pollution at night. I was waking up in the middle of the night at 9 or 10 and slipping out the door and going for a walk.” He maintained his bimodal sleep habits as a Buddhist monk, and now he savors the darkness at his home in the rural Catskill Mountains, where there are no streetlights. (He had a more difficult time as a magazine editor in New York.) Strand describes these periods of nightly wakefulness as “a lost state of consciousness that was once a human birthright.” When people meditate or pray the rosary, he believes, “they’re trying to cultivate darkness, that sort of space where their mind isn’t a slave to calculated thinking or to the culture, where the body can be at peace and the mind can retreat within itself.”

But can those of us who live in cities—magazine editors in New York, say—reclaim those nocturnal hours? The eight hours of work and the eight of recreation already mount a nightly assault on our eight hours of rest, stealing an hour for our email inbox and another for our Netflix queue. Can we really set aside another two or three hours without bulbs or screens, to reflect and relax and, perhaps, rut? It sounds lovely, and all you have to do to achieve it is to go to bed at 8 every night. And if you like the idea of having sex during that moony interlude you’ll have to get your spouse on the same schedule—in which case, who in your household is earning a living? Capitalism ruins everything. Good night.

Read more from The Drift, Slate’s pop-up blog about sleep.