Sleep Much?

In case you've been wondering, according to a new book on the history of Night, Carpe Noctem,just put out by A. Roger Ekirch, we've all been probably been sleeping wrong for a few hundred years.

Here's a review:

http://www.newyorker.com/critics/books/articles/050530crbo_books

And here's the key bit of argument:


What rouses us from our own dogmatic slumbers, however, is Ekirch’s assertion that “until the close of the early modern era, Western Europeans on most evenings experienced two major intervals of sleep bridged by up to an hour or more of wakefulness.” People, evidently, awoke after midnight and, instead of tossing and turning, they regularly got up to talk, study, pray, and do chores.

In case we’re skeptical, Ekirch has found references to the “first sleep,” or primo somno, and the second sleep, sometimes called “morning sleep,” in literature and letters. He has dug up a medical text that advised people with digestive problems to fall asleep on their right side during “the fyrste slepe,” and “after the fyrste slepe turne on the lefte side”; and he assures us that Plutarch, Livy, and Virgil all invoked the term. Indeed, Ekirch supplies enough corroboration regarding the first and second snoozes to make segmented sleep seem like one of those customs, such as bundling and dog-baiting, which simply disappeared.

“That all men sleep by intervals” required no further elaboration from John Locke, who did much of his sleeping during the latter part of the seventeenth century. Two hundred or so years later, as Ekirch sees it, artificial light had become so prevalent that people’s sleep patterns began to change. Those who lived in cities were now able to work, read, and play long after nightfall, and segmented sleep gradually disappeared from urban culture.

What evolved is a shorter, seamless sleep, which, on the face of it, doesn’t sound that bad. But Ekirch views our truncated sleep not just as a neutral statistic of modern life but as an offense against nature. Not only do we get too little sleep; our increased exposure to luminosity has “altered circadian rhythms as old as man himself.” This, rather dismayingly, turns out to have some support in the medical community.

In a study conducted at the National Institute of Mental Health which re-created conditions of “prehistoric” sleep, Dr. Thomas Wehr deprived volunteers of artificial light for up to fourteen hours at night for a span of several weeks. As Ekirch notes, the “subjects first lay awake in bed for two hours, slept for four, awakened again for two or three hours of quiet rest and reflection, and fell back asleep for four hours before finally awakening for good.” In short, they began to exhibit “a pattern of broken slumber—one practically identical to that of pre-industrial households.”

Wehr also observed that “the intervening period of ‘non-anxious wakefulness’ possessed ‘an endocrinology all its own,’ with visibly heightened levels of prolactin, a pituitary hormone best-known for stimulating lactation in nursing mothers and for permitting chickens to brood contentedly atop eggs for long stretches of time.” And because Wehr “likened this period of wakefulness to something approaching an altered state of consciousness not unlike meditation,” Ekirch proposes that we have lost touch with that deeper, more primal aspect of ourselves which emerges during moments after the first sleep.

“By turning night into day,” he writes, “modern technology has helped to obstruct our oldest path to the human psyche.” If Ekirch is correct, then Thomas Edison placed entirely too much faith in his lighting device. “Put an undeveloped human being into an environment where there is artificial light,” Edison predicted, “and he will improve.”

But will he sleep as nature intended? It’s hard to say. Most scientists are confident that internal biological timers regulate body temperature, hormone production, and sleep levels; and they’re pretty sure that the suprachiasmatic nucleus, in the hypothalamus, regulates circadian oscillations. The neurobiology of the sleep-wake cycle is not in dispute, but it’s one thing to know that some psychotic episodes are linked to malfunctioning biological clocks, and quite another to assert that segmented sleep is essential to some deeper understanding of who we are.