New Study: The Later You Go to Bed, the Fatter You Are

Welp, this makes me feel better about my grandma-style bedtime of 9 p.m. sharp: A new study published in the October issue of Sleep suggests that regularly nodding off late at night could be linked to weight gain.

As the New York Times reports, the study followed over 3,000 people from 1996 through 2009. Researchers checked in with them three times throughout the 13-year period, collecting information on their normal bedtimes, how often they ate fast food, their exercise habits and how much television time they clocked on average. They also calculated each participant’s BMI at each interview.

In the end, they found the later participants went to sleep, the higher their BMIs were. In fact, for every hour participants pushed off sleep during the week, their BMI jumped two points, even if they were still getting eight full hours of sleep each night. Surprisingly, exercise and TV time didn’t contribute to the jump in BMI, though, unsurprisingly, fast-food consumption did.

So why the link between later bedtimes and higher BMIs? Well, the researchers don’t quite know. As the lead author of the study said to the Times, “Is it metabolic changes that happen when you stay up late? … if we change sleep patterns, can we change eating behavior and the course of weight change?” No answers to those questions yet. Until then, I’ll be sticking to my as-soon-as-the-sun-sets bedtime, thank you very much.

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