You just might want to rethink those 3 AM Netflix and chill sessions.
A new study funded by a grant from the National Institutes of Health says that people who go to sleep late—even if they get an adequate amount of sleep—tend to have a poor diet and are putting themselves at greater risk of becoming obese. The findings, which probably shouldn't come as much of a surprise, were particularly true among men.
The study looked at 96 healthy adults between the ages of 18 and 50, who all slept more than six-and-a-half hours per night, so sleep duration wasn't the problem. But those who delayed their sleep—in other words, went to bed late—were found to eat more fast food, fewer vegetables, and didn't exercise enough.
The subjects of the study wore wrist actigraphs, which measured their sleep. They filled out food diaries, which helped the researchers measure their caloric intake and their dietary patterns. And, they wore SenseWear arm bands to monitor their physical activity. After examining the subjects' melatonin onset and body fat—and controlling for age, sex, sleep duration, and sleep efficiency—the scientists found this: When you fall asleep can influence how and what you eat. It can also affect how much you exercise. And if you tend to delay going to sleep—you're screwed. You're more likely to eat shitty food and loaf around all day.
Previous studies have showed that not sleeping enough is associated with junk food cravings and weight gain. But this study showed that those whose body clocks mirror those of vampires and rock gods are at risk, thanks to the lousy habits their lifestyles appear to engender.
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Principal investigator Kelly Glazer Baron, an associate professor of neurology at the Feinberg School of Medicine at Northwestern University in Chicago, said, "Our results help us further understand how sleep timing in addition to duration may affect obesity risk. It is possible that poor dietary behaviors may predispose individuals with late sleep to increased risk of weight gain."
The results, mind you, found a correlation between sleep timing and bad food and exercise habits—it didn't actually find that late sleepers were fatter than their early-to-bed counterparts. The body mass indexes of the subjects who fell asleep later were not, in fact, greater than those who retired early. Still, the risky behavior of the night owls has the researchers concerned.
Turns out, perpetually throwing an all-night bacchanalia for a bunch of actual night owls isn't the best of ideas.