Feeling Tired?Your Health by Shirley Learthart Feeling more tired since the clocks went back? According to researchers in the US, a human's natural sleep pattern is similar to that of chipmunks and other animals which sleep for long periods during winter. The research suggests that artificial lighting may be forcing humans into unnatural sleeping habits, disrupting seasonal variations in sleep patterns and causing widespread sleep deprivation. It speculates this could eventually lead to health problems. The researchers studied sleep patterns of 16 people who spent their nights in a windowless room in the lab. For one week, the lights were out for eight hours each night, simulating the 16 hours of daylight common during summer - and the pattern that has become typical since artificial lighting. After a break of two weeks, the lighting pattern was changed to one more typical of short winter days - and of how humans lived before the light bulb. The lights stayed out for 14 hours. The volunteers slept right through the short summer nights. But during the 14 hours of winter darkness, they generally woke for a time during the night and experienced a period of quiet wakefulness, with brainwaves similar to those produced during meditation. Some of the sleepers stayed in this state for up to 5 hours a night, but they told researchers they felt much more rested and energetic at the end of the winter period than at the end of the summer period of the experiment. The winter sleep patterns were very similar to those of chipmunks, sheep and other animals, which sleep in bouts through the night rather than continuously, says researcher Peter Wehr. “Natural human nocturnal behaviour looks an awful lot like animal nocturnal behaviour.” There was also a noticeable change in the secretion of hormones, with production of more growth hormone, prolactin and melatonin during winter. This suggests that artificial lighting may have altered the natural pattern, leaving people producing less than they should. Results of this study support a study by Roger Ekirch in a book called At Day's Close: Night in Times Past, which is about night in preindustrial times. He states that before artificial illumination was widely used, persons typically slept in 2 shifts - "first sleep" and "second sleep." - and sleep was more closely associated with sunset and sunrise than it is now. Sleep tight For more preventative health information, |
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