Restless Nights – The Evolution of Sleep

Last month, Marvin Anthony Alexander of Phenix City, Ala., drove his SUV over a guardrail, falling 40 feet to the highway below and killing three teenaged passengers. Police determined that he was not under the influence at the time, but instead had fallen asleep at the wheel after an extended drive back from a vacation. Alexander, although he experienced the worst of what sleeplessness has to offer, is far from alone in his condition: according to a recent poll by the Centers for Disease Control and Prevention, 32 percent of Americans admit to “drowsy driving” on at least a monthly basis, and the National Sleep Foundation reports that 20 percent of US adults get less than six hours of sleep nightly. The basic sleep need of adults is generally agreed to be in the range of seven to nine hours nightly, and most experts recommend that this sleep come in a single, unbroken block.

Yet according to Roger Ekirch, a historian at Virginia Tech University, this recommendation may actually be counterproductive to achieving proper rest.  In his book “At Day’s Close: Night in Times Past,” Ekirch argues that the ideal of eight hours of uninterrupted sleep is a modern invention, promoted by the availability of artificial lighting that disrupted natural sleep cycles. Light suppresses the production of melatonin, a hormone that regulates sleepiness and is of great importance to the body’s circadian rhythm, or “biological clock.” Before streetlamps and lightbulbs, the night was significantly darker, and historical records suggest that people divided the night with two periods of sleep, scientifically known as biphasic sleep. Between the “first” and “second” sleeps came an hour or two of wakefulness, during which people would do everything from pipe smoking to visiting neighbors to praying. As sleep scientist Thomas Wehr writes, “Waking up after a couple of hours may not be insomnia. It may be normal sleep.”

Sample sleeping schedules, courtesy of Chase Hamilton.

Some adventurous sleepers are trying to break their rest into even further divisions in patterns of polyphasic sleep, often with the goal of reducing the total time spent in bed. These patterns aim to maximize the proportion of rapid eye movement (REM) sleep, the stage associated with dreaming, which is considered most important in helping the brain cement what it has learned over the course of the day. One of the most extreme sleep designs is called the “Uberman” schedule, which calls for less than three hours of sleep a day, broken into 20-30 minute chunks distributed every four hours. Scientific evidence on the success of these patterns is limited, but the Internet abounds with polyphasic success stories (as well as a considerable number of failures).

The temptation to reduce the time spent asleep and channel it into more productive activity is understandable, but fails to recognize the basic needs of the body. Whether it be in an unbroken stretch or the two halves perhaps favored throughout history, adequate sleep is absolutely necessary for human health and well-being.

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