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Outside Magazine, April 2005

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Out There
Miles to Go Before I Sleep (cont.)

STAMPI IS SLENDER and has an easygoing international charm; he was born to Italian parents in S‹o Paulo, Brazil, where his love of sailing began at age three. Striking photos from his many adventures at sea, which include two round-the-world races, are all over his house, as are vestiges of the boats he has loved—including sections of a broken mast and a cabin door that he uses as his work table.

After a childhood spent messing around on boats, he moved to Italy as a teenager and went on to receive his medical degree. "I had conflicting desires in life," Stampi says, "but as soon as I encountered chronobiology, I knew I could find a way to merge the sacred—medicine—and the profane, sailing."

That meant entering the first round-the-world sailboat event he could find—the 1975 Clipper Race, from the United Kingdom to Australia and then on around Cape Horn and back to the start—to do some onboard research. Stampi monitored the sleep patterns, body temperatures, and cognitive performance of his six crewmates every two hours. He turned the resulting data into his dissertation.

The benefits of frequent naps made sense to the sailor in Stampi, who understood the demands of a boat. But he had no scientific proof that, in situations of sleep deprivation, polyphasic sleep—the term for frequent napping—was more efficient than monophasic (getting sleep all in one chunk).

So in 1990 he turned from the docks to the Cambridge, Massachusetts-based Institute of Circadian Physiology's research labs, rounding up some willing test subjects and dividing them into three groups. Each group would sleep only three hours in 24. One group would take all three hours at once. A second would sleep an hour and a half at night and then take three naps during the day. And the last group—the true polyphasics—would accumulate all their sleep in half-hour naps every four hours.

Stampi began by testing the performance of his subjects when they were getting a full eight hours of normal sleep, administering a short cognitive test that was easy to repeat. Then he had them shift to their three-hour routines. After more than a month, the monophasic group showed a 30 percent loss in cognitive performance. The group that divided its sleep between nighttime and short naps showed a 25 percent drop. But the polyphasic group, which slept exclusively in short naps, showed only a 12 percent drop.

Stampi was not surprised by the numbers. As he explained to me, there are two types of sleep: REM sleep, which is important for memory and learning, and non-REM sleep, which restores energy and releases hormones for growth and development. Non-REM sleep occurs in four stages: Stage one is a light slumber; stage two marks the onset of real sleep, where the heart rate and breathing slow; and stages three and four provide the deep (or slow-brainwave) sleep that is most highly restorative.

Generally speaking, sleepers cycle through these stages about every 90 minutes, with a pit stop for REM sleep between each cycle. Interestingly, the body seems to want its slow-wave fix first, and racks up most of the slow-wave quota in the first three hours. If you slash eight hours of sleep to four and your body has to triage, you retain 95 percent of the slow-wave sleep while ditching large chunks of REM and stage-two sleep. "That suggests that slow-wave sleep is the most critical," Stampi says. "Sleep charges your battery more at the beginning of the sleep cycle than at the end, so if you take more naps you are recharging more efficiently, because you take that first big charge frequently."

Ripping up normal patterns to sleep almost exclusively in short naps sounds extreme, but as Stampi points out, approximately 85 percent of mammals are polyphasic sleepers. In fact, he says, until about 10,000 years ago—before humans developed the tools and skills that allowed them to stop worrying constantly about becoming some hungry predator's next meal—humans probably were too. Infants are polyphasic sleepers, and even today there are remote hunter-gatherer tribes in Malaysia that sleep four to six hours a night and nap frequently during the day. Perhaps the most famous polyphasic sleeper was Leonardo da Vinci, who supposedly slept only 15 minutes every four hours, for a total of 1.5 hours of shut-eye every 24. "That would help explain his prodigious output," Stampi says. "But I suspect he only used that mode when he was rushing to dissect fast-rotting cadavers."

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