When: The Scientific Secrets of Perfect Timing(18)
While naps between thirty and ninety minutes can produce some long-term benefits, they come with steep costs. The ideal naps—those that combine effectiveness with efficiency—are far shorter, usually between ten and twenty minutes. For instance, an Australian study published in the journal Sleep found that five-minute naps did little to reduce fatigue, increase vigor, or sharpen thinking. But ten-minute naps had positive effects that lasted nearly three hours. Slightly longer naps were also effective. But once the nap lasted beyond about the twenty-minute mark, our body and brain began to pay a price.52 That price is known as “sleep inertia”—the confused, boggy feeling I typically had upon waking. Having to recover from sleep inertia—all that time spent splashing water on my face, shaking my upper body like a soaked golden retriever, and searching desk drawers for candy to get some sugar into my system—subtracts from the nap’s benefits, as this chart makes clear.
With brief ten-to twenty-minute naps, the effect on cognitive functioning is positive from the moment of awakening. But with slightly longer snoozes, the napper begins in negative territory—that’s sleep inertia—and must dig herself out. And with naps of more than an hour, cognitive functioning drops for even longer before it reaches a prenap state and eventually turns positive.53 In general, concludes one analysis of about twenty years of napping research, healthy adults “should ideally nap for approximately 10 to 20 minutes.” Such brief naps “are ideal for workplace settings where performance immediately upon awakening is usually required.”54
But I also learned I was making another mistake. Not only was I taking the wrong kind of nap, I was also failing to use a potent (and legal) drug that can enhance a short nap’s benefits. To paraphrase T. S. Eliot, we should measure out our naps in coffee spoons.
One study makes this case. The experimenters divided participants into three groups and gave them all a thirty-minute midafternoon break before sitting them at a driving simulator. One group received a placebo pill. The second received two hundred milligrams of caffeine. The third received that same two hundred milligrams of caffeine and then took a brief nap. When it came time to perform, the caffeine-only group outperformed the placebo group. But the group that ingested caffeine and then had a nap easily bested them both.55 Since caffeine takes about twenty-five minutes to enter the bloodstream, they were getting a secondary boost from the drug by the time their naps were ending. Other researchers have found the same results—that caffeine, usually in the form of coffee, followed by a nap of ten to twenty minutes, is the ideal technique for staving off sleepiness and increasing performance.56
As for me, after a few months of experimenting with twenty-minute afternoon naps, I’ve converted. I’ve gone from nap detractor to nap devotee, from someone ashamed to nap to someone who relishes the coffee-then-nap combination known as the “nappuccino.”*
THE CASE FOR A MODERN SIESTA
A decade ago, the government of Spain took a step that seemed distinctly un-Spanish: It officially eliminated the siesta. For centuries, Spaniards had enjoyed an afternoon respite, often returning home to eat a meal with their family and even snag a quick sleep. But Spain, its economy sluggish, was determined to reckon with twenty-first-century realities. With two parents working, and globalization tightening competition worldwide, this lovely practice was stifling Spanish prosperity.57 Americans applauded the move. Spain was finally treating work with sufficient, and sufficiently puritanical, seriousness. At last, Old Europe was becoming modern.
But what if this now-eliminated practice was actually a stroke of genius, less an indulgent relic than a productivity-boosting innovation?
In this chapter, we’ve seen that breaks matter—that even little ones can make a big difference. Vigilance breaks prevent deadly mistakes. Restorative breaks enhance performance. Lunches and naps help us elude the trough and get more and better work done in the afternoon. A growing body of science makes it clear: Breaks are not a sign of sloth but a sign of strength.
So instead of celebrating the death of the siesta, perhaps we should consider resurrecting it—though in a form more appropriate for contemporary work life. “Siesta” derives from the Latin hora sexta, which means “sixth hour.” It was during the sixth hour after dawn that these breaks usually began. In ancient times, when most people worked outside and indoor air-conditioning was still a few thousand years away, escaping the midday sun was a physical imperative. Today, escaping the midafternoon trough is a psychological imperative.
Likewise, the Koran, which a thousand years ago identified sleep stages that align with modern science, also calls for a midday break. It “is a deeply embedded practice in the Muslim culture, and it takes a religious dimension (Sunnah) for some Muslims,” says one scholar.58
Maybe breaks can become a deeply embedded organizational practice with a scientific and secular dimension.
A modern siesta does not mean giving everyone two or three hours off in the middle of the day. That’s not realistic. But it does mean treating breaks as an essential component of an organization’s architecture—understanding breaks not as a softhearted concession but as a hardheaded solution. It means discouraging sad desk lunches and encouraging people to go outside for forty-five minutes. It means protecting and extending recess for schoolchildren rather than eliminating it. It might even mean following the lead of Ben & Jerry’s, Zappos, Uber, and Nike, all of which have created napping spaces for employees in their offices. (Alas, it probably does not mean legislating a one-hour break each week for employees to go home and have sex, as one Swedish town has proposed.59)