Poor sleep linked to obesity

Individuals who are overweight or obese tend to get less sleep per week than their normal-weight counterparts.Researchers from the Eastern Virginia Medical School in Norfolk, USA, interviewed 924 participants, aged 18 to 91 years, who completed questionnaires on medical problems and sleep habits. Three factors affected total sleep time: being a night-shift worker, being a male, and being obese. It was found that the total sleep time decreased as body mass index (BMI), a measure of weight in relation to height, increased except in the extremely obese group. The difference averaged 16 minutes per day between those with normal weight and the heavier participants, amounting to nearly two hours per week. The results were similar when the investigators excluded subjects with specific sleep disorders, such as obstructive sleep apnoea and insomnia.The researchers suggest that lost sleep may lead to metabolic and hormonal irregularities. For example, sleep restriction may reduce levels of leptin, a hormone involved in appetite regulation, thus encouraging weight gain. Or it may simply be related to increased eating during increased time awake.

Obesity is a component of the so-called metabolic syndrome, a cluster of disorders that also include high blood pressure and high blood sugar levels, which increases the likelihood of developing heart disease and diabetes. In a second study, researchers from the VU University Medical Center in Amsterdam did a study that started in 1977 among 13-year-olds, with a 24-year follow-up period. By age 36, 10 percent of the participants had developed the metabolic syndrome. Over time, these subjects had shown more marked increases in total body fat, as well as pronounced decreases in fitness levels. These associations were independent of each other and, therefore, represent separate potential targets for the prevention of the metabolic syndrome.

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