Polyphasic sleep

Based on Wikipedia: Polyphasic sleep

The Sleep Your Ancestors Knew

Here's something strange: for most of human history, sleeping through the night in one unbroken stretch would have seemed bizarre. Our great-great-grandparents went to bed at dusk, woke up around midnight, stayed awake for an hour or two, then drifted back to sleep until dawn. They called this "first sleep" and "second sleep," and they thought nothing of it.

Then electric lights arrived. And somewhere along the way, we forgot.

What We Mean When We Talk About Sleep Patterns

Sleep researchers divide sleep patterns into three broad categories. Monophasic sleep is what most of us do now: one continuous block of sleep per day, typically at night. Biphasic sleep means two separate sleep periods—think of an afternoon nap added to your nighttime rest. And polyphasic sleep involves three or more sleep periods scattered throughout the day and night.

The term "polyphasic" comes from a psychologist named J. S. Szymanski, who coined it in the early twentieth century while studying how animals cycle through periods of activity and rest. What he observed across the animal kingdom was telling: most mammals don't sleep the way modern humans do. Dogs nap throughout the day. Cats are famous for it. Even our closest primate relatives have sleep patterns that look nothing like our neat eight-hour blocks.

This raises an uncomfortable question: Is our modern sleep pattern natural? Or is it an industrial accident?

The Historian Who Uncovered a Lost World

Roger Ekirch spent sixteen years hunting through old documents. What he found changed our understanding of sleep.

In over five hundred historical references—from ancient texts to medieval prayer books to early modern diaries—Ekirch discovered something remarkable. People consistently wrote about "first sleep" and "second sleep" as though everyone knew exactly what that meant. Court records mentioned crimes committed during "the watch," that midnight waking period. Doctors gave advice about the best time for conception—after first sleep, they said, when the body was rested but the mind alert. Prayer manuals assumed readers would be awake at midnight to commune with God.

The pattern Ekirch reconstructed went something like this: People went to bed shortly after dark, around nine in the evening. They slept for three or four hours. Then they woke, naturally, without alarm clocks or disruption. This midnight waking period lasted an hour or two. Some people prayed. Some read by candlelight. Some visited neighbors—yes, in the middle of the night. Some made love. Scholars wrote. Petty criminals got to work. Then everyone returned to bed for their second sleep, waking with the dawn.

What strikes modern readers is how unremarkable this seemed to them. No one treated the midnight waking as insomnia or a problem to be solved. It was simply how humans slept.

Why This Pattern Made Sense

Consider a winter night before electricity. In northern Europe, darkness might last fourteen or fifteen hours. No one can sleep that long. But dividing the darkness into two sleep periods, with a wakeful interlude, made those long nights manageable.

Summer nights were different—shorter, hotter, interrupted by farm work that often started before dawn. The flexibility of biphasic sleep adapted to seasonal rhythms in ways our rigid eight-hour schedule cannot.

There's also something biochemical happening. During that midnight waking period, the brain releases elevated levels of prolactin, a hormone associated with feelings of peace and contentment. Many historical accounts describe this time as uniquely calm and contemplative. Dreams remembered during this period were especially vivid—possibly because the dreamer woke directly from a deep sleep phase rather than drifting gradually to consciousness.

The Experiment That Proved Ekirch Right

In 1992, a researcher named Thomas Wehr conducted an elegant experiment. He took seven healthy men and put them in a controlled environment with fourteen hours of darkness each day—roughly equivalent to a winter night before artificial lighting.

At first, the participants slept enormously. Eleven hours some nights. They were paying off what sleep researchers call "sleep debt," the accumulated deficit from their previous lives of truncated rest.

But once that debt was paid, something fascinating happened.

The subjects naturally settled into biphasic sleep. About four hours of sleep, then two to three hours of quiet wakefulness, then another four hours of sleep. No one told them to do this. They weren't following a schedule. Their bodies simply remembered an ancient pattern.

It took them about two hours to fall asleep initially—a long time by modern standards, but consistent with historical accounts of a gradual drift into slumber rather than the abrupt unconsciousness we expect from exhaustion.

The Siesta: Biphasic Sleep's Surviving Form

Not all preindustrial societies followed the first-sleep-second-sleep pattern. Around the equator, where nights and days remain roughly equal year-round, a different biphasic pattern emerged: one consolidated nighttime sleep plus a daytime nap.

This is the siesta, and it's far from extinct.

The siesta tradition runs through Spain, Italy, Greece, and much of the Mediterranean. Spanish colonialism carried it to the Philippines and across Latin America. In China and India, afternoon rest has deep cultural roots. Even parts of South Africa maintain the tradition.

The logic is simple. In hot climates, the early afternoon is miserable for work. The sun beats down. Energy sags. Why fight biology when you can take an hour's rest and return refreshed?

Yet even the siesta is losing ground. Modern work schedules, air conditioning, and the relentless pressure to be always productive have pushed afternoon napping to the margins. In Spain, surveys show fewer people napping each decade. The siesta may soon join first sleep and second sleep as a historical curiosity.

The Modern Polyphasic Movement

If you spend time in certain corners of the internet, you'll encounter people who have taken polyphasic sleep to extremes.

The "Uberman" schedule—named with tongue-in-cheek grandiosity after Nietzsche's concept of the superior human—involves sleeping only three hours per day, distributed as thirty-minute naps every four hours. The "Everyman" schedule allows a three-hour nighttime core plus three twenty-minute naps, totaling four hours daily.

The inventor and futurist Buckminster Fuller reportedly lived on an even more extreme schedule for two years: thirty-minute naps every six hours, totaling just two hours of sleep per day. According to Time magazine, he only abandoned the practice because his business associates refused to adapt their schedules to match.

The appeal is obvious. If you could function on three or four hours of sleep, you'd gain five additional waking hours every day. Over a year, that's nearly two thousand hours—almost three extra months of conscious life.

The problem? There's no scientific evidence that this works.

While advocates claim to feel fine, sleep researchers point out that humans are notoriously bad at judging their own cognitive impairment. People who are sleep-deprived often believe they're functioning normally even as objective tests show degraded performance. The brain adapts to exhaustion by lowering its own standards for what "alert" feels like.

When Extreme Napping Actually Makes Sense

There's one context where polyphasic sleep isn't lifestyle experimentation but survival necessity: situations where normal sleep is physically impossible.

Solo ocean racing is perhaps the clearest example. Sailors crossing the Atlantic or competing in round-the-world races cannot leave their boats on autopilot for eight-hour stretches. Weather changes. Shipping lanes must be navigated. Equipment fails. So they sleep in fragments—sometimes six or seven short naps per day, clustered more heavily during night hours when sailing hazards are greatest.

Claudio Stampi, a researcher fascinated by this problem, conducted a forty-nine-day experiment where a young man slept only three hours daily in short naps. Brain monitoring showed that remarkably, all stages of sleep—including the deep slow-wave sleep and rapid eye movement sleep usually assumed to require longer periods—somehow compressed into these brief windows.

Stampi's conclusion was measured. In situations of "prolonged sustained performance" where normal sleep is impossible, polyphasic napping helps. But he explicitly did not advocate ultrashort napping as a lifestyle choice.

Military Applications

The armed forces of several nations have studied the same question from a practical standpoint. Combat operations don't pause for sleep schedules. How do you keep soldiers functional when extended rest is impossible?

The United States Air Force recommends naps of at least forty-five minutes when possible, with two-hour naps being preferable. The more fragmented the sleep, the more frequently those fragments should occur. The goal remains eight total hours per day—just distributed differently than civilian sleeping.

Canadian Marine pilots learn a more sobering truth: ten to twenty-minute naps can maintain performance for several days under extreme conditions, but performance never approaches fully rested levels. It's damage control, not optimization.

NASA has studied napping extensively because astronauts routinely struggle to sleep eight consecutive hours in space. Research led by Professor David Dinges at the University of Pennsylvania found that napping effectiveness depends on what cognitive function you need. Basic alertness benefits least from naps. Working memory—the ability to hold and manipulate information—benefits most.

There's also the question of timing. Naps during your biological daytime work well. Naps during your biological nighttime—when your body thinks you should be deeply asleep—produce significant sleep inertia, that groggy fog that can last up to an hour after waking.

The Italian Air Force Experiment

One of the most interesting controlled studies came from the Italian Air Force, the Aeronautica Militare Italiana. They tested a schedule of two hours of activity followed by four hours of rest, repeated four times throughout the day. Subjects could sleep during rest periods if they wished.

What emerged was fascinating. The subjects naturally avoided sleeping during their first rest period, then slept in progressively longer stretches during the remaining three. Total sleep time dropped substantially below the usual seven to eight hours—yet vigilance remained high. The electroencephalogram measurements that track brain activity showed virtually no microsleeps.

Microsleeps are the brain's sneaky way of stealing rest when it's being denied. They're brief—sometimes just seconds—and the person experiencing them usually doesn't notice. But they're measurable, and they're dangerous. A microsleep while driving or operating machinery can be fatal. The fact that Italian Air Force subjects showed almost none suggested their fragmented sleep schedule was genuinely meeting the brain's needs.

When Polyphasic Sleep Isn't a Choice

Not everyone sleeping in fragments is doing so intentionally.

Irregular sleep-wake syndrome is a rare circadian rhythm disorder where the body's internal clock fails to maintain any consistent pattern. People with this condition may sleep in three or four short blocks scattered seemingly at random throughout the day and night. It's most common in people with neurological damage, head injuries, or dementia.

Infants naturally sleep polyphasically—a fact any exhausted new parent knows too well. Newborns may sleep sixteen hours a day, but in dozens of short fragments. The slow consolidation of infant sleep into longer nighttime stretches is one of parenthood's most anticipated milestones.

And at the other end of life, elderly people often return to something like polyphasic sleep. Night wakings become more frequent. Daytime napping increases. A 2006 study by Campbell and Murphy found that when older adults were allowed to sleep freely without schedules, their nighttime sleep was significantly shorter than younger adults', supplemented by daytime sleep periods.

The researchers made a provocative observation: across the entire animal kingdom, polyphasic sleep is the rule rather than the exception. Humans, they suggested, evolved the same way. Our ability to consolidate sleep into one long block isn't natural—it's a triumph of willpower, often assisted by caffeine and artificial lighting. We can override our biology when social circumstances demand it. But our biology remains what it always was.

What This Means for You

If you wake up in the middle of the night and can't immediately fall back asleep, you might not have a sleep disorder. You might have ancestors.

The anxiety that accompanies midnight waking—the clock-watching, the mental calculations of how few hours remain before the alarm—may be making things worse. Our great-grandparents didn't lie in bed panicking about lost sleep. They got up, did quiet activities, and returned to bed when drowsiness returned.

That said, there's little evidence that deliberately fragmenting your sleep will make you more productive. The internet's extreme polyphasic schedules remain unvalidated by serious research. The promised benefits—more waking hours, enhanced creativity, superior focus—may be real for some practitioners, or may be the self-deception of the sleep-deprived convinced they're thriving.

What is clear is that sleep is more flexible than modern life assumes. The eight-hour block isn't a biological requirement but a social convention—useful in industrial economies where work schedules are fixed and artificial lighting allows activity at any hour, but not the only way humans have organized rest.

The next time you wake at three in the morning and can't sleep, consider that your body might be remembering something your culture has forgotten. The watch hour. The time between first sleep and second sleep. A period our ancestors treasured for its quiet, its clarity, and the vivid dreams that preceded it.

You might even find it peaceful.