Thursday, June 19, 2014
Sleep -- Are We Doing It Wrong?
We all understand the importance of a good night's sleep, but many people do not sleep well. The University of Maryland Medical Center estimates that almost two-thirds of us have trouble falling asleep, staying asleep, waking up or feeling rested in the morning.
Accordingly, the United States now has hundreds of sleep treatment centers, and many people take over-the-counter or prescription sleep aids.
Psychologists and historians now suggest that these problems reflect a break with our evolutionary habits.
They have gathered a lot of evidence that suggests that eight hours of continuous sleep may not be as helpful as two periods of four hours of sleep with an interval of one to three hours of quiet wakefulness in between.
Thomas A. Gehr of the National Institute of Mental Health conducted a 1992 study that kicked off the discussion. He put a group of healthy men in an environment with 10 hours of light and 14 hours of darkness each day for a month. At the end of the month, the men had without effort adjusted their habits to sleep in two shifts, each several hours long, punctuated by one to three hours of wakefulness in between. Gehr called this "polyphasic" sleep.
Then historian A. Roger Ekirch published an interesting and readable book (which I recommend) in 2005 called At Day's Close: Night in Times Past.
In it, Ekirch cited references, starting as as far back as Homer's Odyssey, to "first sleeps" and "second sleeps." During the middle period, some people used the toilet or visited neighbors. Mostly, he said people stayed in bed to read, pray and have sex.
The volume of references he cites is compelling. In one instance, he reports the discovery of many 15th century prayer manuals designed specifically for use in the period between first and second sleeps.
In another, he says that Benjamin Franklin took "cold air baths," reading, naked in a chair, during his middle-of-the-night wakeful periods.
Ekirch and psychologists have speculated that this quiet middle period of relaxed reading and reflection may have had the evolutionary benefit of regulating tension and stress that built up during the daytime.
The introduction of artificial light seems to be what killed off the old sleep patterns.
In earlier times, people took shelter from the dark for fear of highwaymen or predatory animals. But gas lamps and, later, electricity allowed some safety. People could venture out at night or keep the lights on indoors. It became easier to stay up later and collapse the longer sleep-wake-sleep routine down to a steady eight hours in bed.
By the 1920s, references to polyphasic sleep had all but disappeared in the West. Even today, though, some African tribal peoples and a number of animal groups continue to live on polyphasic schedules.
I have met several people who have adopted this sleep pattern. Each of them lives alone and has the freedom to set his or her work schedule. They seem to drift into this habit naturally and to find it comfortable, but they are a little defensive about it.
Maybe they could teach us something.