A lack of pillow time could be causing us to pile on the pounds. Sleep deprivation interferes with appetite-regulating hormones and drives us to eat more.
We're definitely sleeping less. According to the National Sleep Foundation, Americans spend an average of six hours and 40 minutes snoozing per weeknight, compared with 10 hours before Edison invented the lightbulb. Findings released last May by the Centers for Disease Control and Prevention illustrate the importance of bedtime: Of 87,000 American adults surveyed between 2004 and 2006, about 33 percent who slept fewer than six hours a night were obese, compared with only 22 percent of those who got the recommended six to nine hours. Previous studies have shown that chronic sleep deprivation increases levels of ghrelin, an appetite-stimulating hormone, and decreases leptin, a hormone that helps you register fullness. And researchers at the University of Chicago who deprived healthy young adults of sleep found that in addition to increased overall appetite, the volunteers experienced a particular surge in cravings for sweet and salty foods.
This hypothesis is plausible and actionable. Sleep researcher James Gangwisch of Columbia University Medical Center believes the existing data is sufficient to recommend getting more shut-eye as a preventive measure. "This is important to the study of obesity because it's a totally unique risk factor," he says, "and, for the most part, it's easily modifiable."
Follow-up studies now under way at the NIH and other institutions should better define the effect of sleep quality versus quantity on weight gain and offer more insights into appetite controls. In the meantime, consider this a science-sanctioned excuse to sleep in.
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