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Getting too little sleep for several nights in a row disrupts hundreds of genes that are essential for good health, including those linked to stress and fighting disease. Tests on people who slept less than six hours a night for a week revealed substantial changes in the activity of genes that govern the immune system, metabolism, sleep and wake cycles, and the body's response to stress, suggesting that poor sleep could have a broad impact on long-term wellbeing. The changes, which affected more than 700 genes, may shed light on the biological mechanisms that raise the risk of a host of ailments, including heart disease, diabetes, obesity, stress and depression, in people who get too little sleep. Previous studies have suggested that people who sleep less than five hours a night have a 15% greater risk of death from all causes than people of the same age who get a good night's sleep. In one survey of workers in Britain more than 5% claimed to sleep no more than five hours a night. Another survey published in the US in 2010 found that nearly 30% of people claimed to sleep no more than six hours a night. The time spent asleep had a huge effect on the activity of genes, picked up from blood tests on the volunteers, according to a report in the US journal Proceedings of the National Academy of Sciences. Among the sleep-deprived, the activity of 444 genes was suppressed, while 267 genes were more active than in those who slept for longer. Changes to genes that control metabolism might trigger or exacerbate conditions such as diabetes or obesity, while disruption to other genes, such as those that govern the body's inflammatory response, might have an impact on heart disease. Further genes that were affected have been linked to stress and ageing. Sleep loss also had a dramatic effect on genes that govern the body's biological clock, suggesting that poor sleep might trigger a vicious cycle of worsening sleep disruption. Jim Horne, professor of psychophysiology at Loughborough University's Sleep Research Centre, said: "The potential perils of 'sleep debt' in today's society and the need for 'eight hours of sleep a night' are often overplayed and can cause undue worry. Although this important study seems to support this concern, the participants had their sleep suddenly restricted to an unusually low level, which must have been somewhat stressful. "We must be careful not to generalise such findings to,then say, habitual six-hour sleepers who are happy with their sleep. Besides, sleep can adapt to some change, and should also be judged on its quality, not simply on its total amount." |
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