Sleep may counteract genetic weight gain

A new study examining sleep and body mass index (BMI) in twins has found that sleeping more than nine hours a night may suppress genetic influences on body weight. Sleeping less than seven hours a night was associated with increased BMI and greater genetic influences on BMI. Previous research has shown that genetic influences include things like glucose metabolism, energy use, fatty acid storage and satiety. The heritability of BMI was twice as high for the short sleepers than for twins who slept longer than nine hours a night. "The results suggest that shorter sleep provides a more permissive environment for the expression of obesity related genes," said principal investigator Nathaniel Watson of the University of Washington. "Or it may be that extended sleep is protective by suppressing expression of obesity genes."