Over the past several decades, obesity has grown to epidemic proportions. In parallel with this rise in weight is the rise in chronic sleep deprivation. According to annual surveys done by the National Sleep Foundation, by 2005 only 26% of American adults were obtaining 8 hours of sleep and 40% of American adults report obtaining <7 hours of sleep.
Evidence has grown over the past decade supporting a role for short sleep duration as an independent risk factor for weight gain and obesity.
Total sleep deprivation experiments in animals and humans have consistently found sleep deprivation produces increased intake of food, especially high fat and high carbohydrate foods. These changes corresponded with elevations in serum ghrelin (a hormone that stimulates hunger and food intake) and reductions in serum leptin (a hormone associated with satiety and feelings of fullness).
In a large sleep study that has been going on in Wisconsin for over 15 years, researchers found that people who slept less were on average heavier. People who slept less had lower levels of leptin and higher levels of ghrelin, which is likely to increase appetite. In other words, short sleep might stimulate appetite, which increases weight.
Similar findings were seen in the Québec Family Study where short-duration sleepers (5-6 hours of sleep) were found to have leptin values significantly lower than predicted values and correlated with increased body fat mass and risk of being overweight/obese.
A study restricting sleep for six consecutive days found a similar reduction in leptin that persisted throughout the 24 hour day.
Although there may be other mechanisms which link short sleep duration and increased weight, optimal sleeping hours may positively influence the hormones which regulate appetite and body weight, and should be a lifestyle factor to address when managing weight loss and long term weight maintenance.
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