More Studies Link Lack of Sleep to Overweight

Karen Collins, MS, RD, CDN
American Institute for Cancer Research

As the numbers of obese continue to rise, researchers are exploring the possible connection between obesity and how too many of us -both adults and children- are getting too little sleep. A recent report in the Journal of the American Medical Association observed that a decline in daily hours of sleep may play more of a role in promoting overeating and weight gain than previously thought. Researchers say that lack of sleep could increase tendencies to become overweight by affecting hormones, mental function, and behavior itself.

Almost one-third of adults report sleeping six hours or less a night. In one study of more than 900 patients ranging in age from 18 to 91, those who were overweight or obese reported fewer hours of sleep per night than those at a healthy weight. A large population study of adults ages 32 to 49 associated sleep habits with obesity. Compared to those who slept at least seven hours a night, adults reporting 6 hours of sleep were 23 percent more likely to be obese; those averaging 5 hours were 50 percent more likely to be obese; and those sleeping four hours or less nightly were 73 percent more likely to be obese.

Adults are not the only ones whose sleeping habits may be affecting their weight. A new study of children ages 5 to 10 in Quebec associated children?s sleep habits with the risk of overweight or obesity. When compared to children who sleep 12 to 13 hours a night, risk of overweight or obesity increased 42 percent in those sleeping 10.5 to 11.5 hours, and more than tripled in those sleeping 8 to 10 hours.

For adults, studies show weight begins to increase beginning with those who average less than seven hours of sleep a night. Since 2000, 13 large population studies have linked less sleep with higher weight. Those who are most severely obese are one of the few exceptions. This is most likely because sleep apnea (breathing difficulty during sleep) and other sleep disorders caused by obesity may leave people so tired that they sleep more hours. Adults over 50 years old may be another exception. It is not clear whether older adults need less sleep, or if the effects of inadequate sleep are hidden among other health issues in this group.

Several studies show that lack of sleep seems to change the levels of two appetite-related hormones. A hormone called ghrelin that stimulates appetite may increase, and the hormone leptin that tells our body we have had enough food may decrease. Together these changes would lead us to feel we need to eat more, even when we may have consumed all the calories we need. Some research suggests that other hormones, including those affecting blood sugar, may also be affected by lack of sleep.

Inadequate sleep affects the way we make decisions, too. According to a report from the National Sleep Foundation, at least two-thirds of adults say sleepiness interferes with their concentration and ability to handle stress. That means that we may be more likely to eat in an effort to increase energy or cope with stress. When we are not well rested, we may not exercise at all or exercise at a lower intensity.

A new study has begun to test whether obese adults who get too little sleep will lose weight if they sleep more. Meanwhile, if you feel that you?ve been fighting an uphill battle trying to manage your weight, test yourself. Find something that relaxes you before bed, and make seven to eight hours of sleep nightly a priority. You’ve nothing to lose by increasing the amount you sleep as part of an overall healthy lifestyle.


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