About two years ago, we posted First Sleep, Second Sleep, which became the 12th most-read post on this blog, with people to this day clicking on it. It had to do with what historians have discovered about sleep patterns in the days before artificial lighting, from ancient and Biblical days through the 17th century. People would go to bed shortly after it turned dark, sleep for four hours, wake up for two or three hours, then go back to sleep for another four hours. During the period of wakefulness between “first sleep” and “second sleep,” people would talk, read, and pray. This seems to have been the main time when married couples would make love. Artificial lighting–not just candles but oil lamps and especially electric lighting–changed people’s sleeping patterns, letting us stay up late, though patterns of insomnia suggest that first sleep and second sleep is deep wired into our nature.
Anyway, researchers have been studying this phenomenon. Test subjects made to go to sleep when it gets dark, after a period of adjustment, fall back into the pattern. But then scientists discovered something else. That time between first sleep and second sleep is characterized by a unique state of consciousness. Although the person is fully awake, he or she is in a state of deep rest, relaxation, and peace.
Clark Strand, who has written a book on the subject, relates it to the “mindfulness” of Eastern meditation. I don’t think we have to go all mystical about it, like he does (though the connection might suggest why “the night watches” were such a good time for Bible reading and prayer), but I’m curious what this would have meant for marriages. Marital intimacy–sex, yes, but also conversation–may well have been heightened during this nightly state of mind. “Sleeping together” may have been more than a euphemism, perhaps a description of an deep intimacy that may be difficult to attain today.
During the mid-1990s, sleep researcher Thomas Wehr conducted a National Institutes of Health experiment that he later called an exercise in “archaeology, or human paleobiology.” Wehr wanted to find out if modern humans still carried within them the rhythms for a prehistoric mode of sleep. Did prehistoric humans sleep more? Did they sleep differently — or perhaps better?
Wehr’s logic was simple: Aided by the stimulating effects of all kinds of artificial lighting (everything from laptop screens to the bright lights of big cities), modern humans had compressed their sleep nights, like their work days, into convenient eight-hour blocks. And yet, given that light-assisted wakefulness was a relatively new invention, wasn’t it possible that human beings still carried in their DNA the remnants of a more primordial pattern of sleep?
The results were staggering. For one month, beginning at dusk and ending at dawn, Wehr’s subjects were removed from every possible form of artificial light. During the first three weeks, they slept as usual, only for about an hour longer. (After all, he reasoned, like most Americans, they were probably sleep deprived.) But at week four a dramatic change occurred. The participants slept the same number of hours as before, but now their sleep was divided in two. They began each night with about four hours of deep sleep, woke for two hours of quiet rest, then slept for another four.
During the gap between their “first” and “second” sleep, Wehr’s subjects were neither awake nor fully asleep. Rather, they experienced a condition they had never known before — a state of consciousness all its own. Later Wehr would compare it to what advanced practitioners experience in meditation — what you might call “mindfulness” today. But there weren’t any mindfulness practitioners in his study. They were simply ordinary people who, removed for one month from artificial lighting, found their nights broken in two.
While trying to account for the peace and serenity that his subjects reported feeling during their hours of “quiet rest,” Wehr discovered that prolactin (the hormone that rises in nursing mothers when their milk lets down) reached elevated levels in their bodies shortly after dusk, remaining at twice its normal waking level throughout the full length of the night. Prolactin creates a feeling of security, quietness and peace. And it is intimately, and biologically, tied to the dark.
Even during their hours of quiet rest, the prolactin levels in Wehr’s subjects remained steady. Normally, if you wake in the night, those levels will go down — even if you don’t turn on the lights. But if you turn the lights off at dusk and keep them off, giving your body the full spectrum of the night to work from, that richer, deeper darkness will fashion an experience so different from your normal daylight consciousness it is almost a mystical state.