Chronic sleep deprivation makes you fatter - much fatter
People who sleep an average of 5 hours per day become fat twice as fast as people who get 7-8 hours of sleep per day. Epidemiologists from Case Western Reserve University discovered this in a study in which they followed 70,000 women for 16 consecutive years.
Sleep & obesity
Sleep deprivation stimulates appetite hormones and reduces insulin sensitivity. This explains why in a study by the University of Bristol, for every hour that women sleep on average, their fat percentage decreases by three percent. It also explains why, in a study of American Latinos, obesity is more common in people who don't get more than five hours of sleep per day.
The largest known study of the association between obesity and sleep dates back to 2006, when the American Journal of Epidemiology published a study in which Sanjay Patel of Case Western Reserve University produced the figures below based on data from the classic Nurses' Health Study.
You see that women who slept for 5 hours per year gained 0.62 kg per year. In a period of 16 years, the first group of women therefore put on almost ten kg more body weight - read: body fat. In women who slept 7 or 8 hours a day, the increase in body weight was about half as much.
Here you will find information to help you interpret the figures.
The figures above show that the chance of an extreme increase in body weight in women who slept 5 hours per 24 hours was tens of percent higher than in women who slept 7 hours per 24 hours. Interestingly, the association persisted after the researchers adjusted for energy intake. This suggests that sleep deprivation lowers the basal metabolic rate.
"Increasing sleep time among those sleeping less than 7 hours per night may represent a novel approach to obesity prevention", the researchers write.
"Given the inadequacies of current obesity therapy, the ability of public health initiatives focusing on sleep hygiene to slow the epidemic of weight gain should be investigated, as should the mechanisms linking sleep duration to obesity."
Am J Epidemiol. 2006 Nov 15;164(10):947-54.
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