sunriseUntil recently, the supremacy of 8 to 9 hours of uninterrupted sleep for optimum health has gone unchallenged. A peaceful night of continuous sleep seems to be the elusive goal that doctors recommend and that we are all hoping to obtain. Yet many of us, despite following the advice of sleep therapists or owning a comfortable mattress, continue to wake up in the middle of night. To compound matters, random waking can cause anxiety about getting enough rest before work the next day, making falling back to sleep that much more difficult. Recent research, however, may explain this late-night tossing and turning and perhaps shed light on one of the causes of elevated stress levels in modern society.

In At Day’s Close: Night in Times Past, historian Roger Ekirch reveals that before the Industrial Revolution, people used to sleep in two distinct chunks, which people from the time referred to as “first sleep” and “second sleep.” Psychiatrists and other researches call this type of sleep cycle “polyphasic” or “bi-segmented.” A bi-segmented sleep pattern has been observed among some primitive cultures, as well as various animals, but until now it was assumed that most people throughout history slept once per day for a continuous period. It turns out, however, that before the invention of electricity, people were more in-tune with the natural rhythms of light and dark in nature.

By reading hundreds of documents from the early modern period (1500-1800), Ekirch found that people repeatedly referred to a “first” and “second” sleep, as well as a period of semi-wakefulness in-between sleeps. People would usually wind down for bed as soon as it started to grow dark, fall-asleep for about 4 hours, wake for 1 to 3 hours, and then fall back asleep for another 4 or more hours. The time between “first” and “second” sleeps was used for a variety for purposes. After a long day of work, for many it was the best time of peace and relaxation, the perfect time to visit with loved ones or friends. For others, such a writers and philosophers, it proved the perfect time for thinking and journaling. Doctors advising married couples on how to conceive, recommended it as the best time to have sex, as it was during this period that the couple would be most relaxed and rejuvenated. Psychiatrist Walter Brown believes that such a sleep schedule may have helped people better cope with the stresses of daily life.

The tendency for humans to sleep in two phases in the lack for artifical light was confirmed recently by several experiments performed by psychiatrist Dr. Wehr. In one experiment in-particular, Dr. Wehr found that when individuals were transfered from 16-hours of light exposure (what most experience as a result of artificial lighting) to only 10-hours of light exposure per day (equivalent to a winter day without any artificial light), the subjects sleep cycles naturally split into two distinct periods with 1-3 hours of wakefulness in-between.

So is there a lesson from all of this? At this point it’s difficult to say for sure, but it’s not hard to imagine that living without artificial lighting would help us get more rest and better deal with the stresses of life. Yet while going without artificial lighting for a time might be a fun experiment, for most of us it’s unrealistic. If anything, maybe we can try to live a little more with the rhythms of nature by turning the lights or TV off a little bit earlier at night. Also, in the event we do wake up at night, perhaps we can find some solace in the knowledge that it might be because of our body’s natural sleep cycle. Honest research continues to reveal how technology and societal “advancements” affect our health in unforeseen (and often negative) ways. Personally, I believe that the more we trust in God’s provision and enjoy the goodness of his nature, the healthier we will become.

References: At Day’s Close: Night in Times Past, by Roger Ekrich; In short photoperiods, human sleep is biphasic. Dr. TA Wehr; Acknowledging Preindustrial Patterns of Sleep May Revolutionize Approach to Sleep Dysfunction Dr. Walter Brown

Recommended Reading: The Neuroscience of Sleep with Russell Foster

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Originally posted 2013-03-13 23:30:56.


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