Why Napping Can't Replace a Good Night's Rest

Eight hours of uninterrupted sleep per night—it’s so widely recommended it approaches an axiom. The strange thing is, there’s nothing natural about it. In a landmark 1992 study, Thomas Wehr demonstrated that humans, like many other animals, are naturally inclined to sleep in bouts, separated by periods of activity. Given 10 hours per day of light, instead of the modern sixteen hours of artificial lights-on time, subjects sleep in two symmetrical blocks of several hours each. In the middle of the night, they wake up fully for up to three hours.

In 2010, I gave a talk at TEDGlobal in which I described this alternative sleeping pattern as a candidate for our ancestral sleep schedule. Pre-industrial literature fromCanterbury Tales to Wuthering Heightsdescribes a “first sleep” (sometimes called “beauty sleep” or “dead sleep”) and a “second sleep” in early modern English society. And ever since that talk was translated into 39 languages and approached the two-million-view mark, I have been receiving emails from polyphasic sleepers—people who sleep in spurts around the clock.

There is a seemingly inexhaustible supply of people who want to experiment with their own sleep. With the rise of productivity culture, time is money, both in the literal sense and in a broader kind of experiential currency. Many resent the third of their lives lost to unconsciousness and wish to be present for more of it. Some of those people—overwhelmingly male, in late adolescence—try sleeping polyphasically, in bits. If naps can be refreshing, the logic goes, perhaps that’s all we really need.

Buckminster Fuller, who prefigured our current crop of MIT-dropout geniuses in twice being expelled from Harvard, was in some ways a lifelong adolescent male. He spent a couple of years following a “Dymaxion sleep schedule” in which he would work for several hours, nap briefly, then work again, around the clock. He marveled at his productivity within a 22-hour daily waking life.

Though Fuller’s rhythm was dictated by his fatigue levels, and so entailed flexibility, a movement struck up around polyphasic sleeping on rigid schedules. 

The unfortunately named “Uberman schedule” involves twenty-minute naps every four hours, while the “Everyman schedule” at least recognizes the need for a core sleep—albeit usually less than three hours, with naps in between. There is little interest among this crew in the two-phase sleep of our ancestors, presumably because it does not result in more time spent awake and, one senses, manically typing lines of code into a laptop. 

Scientists have attempted to study the effects of such a schedule, but it is very difficult when the vast majority of one’s test subjects drop out within a few days from the sheer misery of life. If round-the-clock napping is healthy, it sure doesn’t feel like it. A word of warning to those adolescent males who haven’t finished growing: One robust finding is that the release of growth hormone is strongly suppressed during polyphasic sleep, and its timing goes haywire.

Severe sleep deprivation activates a “recovery sleep” whenever a person finally gets shuteye. In this state, the power of the slowest brainwaves is much stronger. In other words, exhaustion brings on deeper sleep, which is why catching up on a lost night of sleep does not require an hour-for-hour reckoning. Polyphasic sleep, then, becomes more efficient as exhaustion increases. During naps, the body makes a valiant effort to survive. - Read More at the Atlantic

Polyphasic Sleep Can't Replace a Good Night's Rest