Broken sleep is normal

I rarely sleep through the night or get the recommended eight hours. Though I fall asleep quickly and I’m in bed for eight hours, I’m only asleep for about six of those hours. I use the wakeful time to get my thinking done. Sometimes this wakeful period is productive; sometimes it’s boring. At any rate, I always feel fine the next day and don’t worry about it. I do take a ten-minute nap after lunch.

I figure that my sleep pattern is normal. When talking to friends, I’ve learned that nearly all of them have similar experiences. It turns out that the “lie down and die” model of sleep, in which we attempt to lie perfectly still for a solid eight-hour block, is a relatively new model that coincides with the industrial age. Like me, pre-industrial people experienced a similar “broken” pattern, splitting their slumber into “first” and “second” periods. Kroger Ekrich, author of At Day’s Close: Night in Times Past, says “there is every reason to believe that segmented sleep, such as many wild animals exhibit, had long been the natural pattern of our slumber before the modern age, with a provenance as old as humankind.” When you look at the conditions under which humans evolved, it doesn’t make sense that they’d basically go unconscious for eight hours in a row. There were too many pressures and predators to contend with. What’s more, some non-Western peoples, such as the !Kung hunter-gatherers in Africa or Balinese farmers in Indonesia have no specific bedtimes. Rather, they drift in and out of slumber depending on what’s happening on any given night.

In the early 1990s, Dr. Thomas Wehr at the National Institute for Mental health conducted an experiment to duplicate sleep patterns before the invention of gas or electric lights. He did this by placing volunteers in an environment lit with only natural light. After a while, his volunteers drifted into a pattern in which they slept for a few hours then awoke for a period of “meditative wakefulness” then fell back asleep again. Sounds just like me.

Of course, we do live in environments of artificial stimuli—lots of it. But we adjust. As Dr. James J. McKenna, an anthropologist who studies sleep says, “Our bodies move toward adaptation, not pathology. Given the sensory context [the stimuli of modern life] our sleep is probably appropriate to the challenge.”

Yet, we’re told that if we don’t sleep eight hours, we’re killing ourselves. Actually, just the opposite is true. Studies have shown that people who sleep between 6 and 7 hours live the longest. More than seven hours of sleep is associated with progressively increasing risk of death, especially from heart disease. Men who sleep more than eight hours a night have been found to have twice the risk of overall death and about three times the risk of dying of heart disease as those who sleep less. Yet, we worry about sleeplessness and look for remedies; exactly what the drug companies encourage.

Next week: The dangers of sleeping pills

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