When it feels like there just are not enough hours in the work week, getting to bed on time is one of the first things to go out the window—which can worsen the negative health effects of stress, such as that pesky weight gain.
Good news, though: You can escape the downward spiral of drowsy mornings, extra-large coffees, and mid-afternoon sugar binges. According to a new study published in Sleep, it may be as simple as sleeping in for a few extra hours on the weekend.
In a study of more than 2,000 Koreans, researchers found that those who had poor sleep during the work week but slept in on the weekend had lower BMIs (a.k.a. ‘body mass indexes’) than those who slept poorly during the week but did not sleep in on weekends, says lead study author Hee-Jin Im, M.D., Ph.D., of Korea University’s Department of Neurology.
The researchers surveyed and interviewed thousands of participants—who ranged from 19 to 82 years old—about their sleep habits, occupations, and other components (like mood and stress levels) that may influence BMI, Im says. While age, physical activity level, and occupation all played roles in each participant’s BMI, the total number of hours of sleep they got per week—and how they slept on the weekend—turned out to be key for those who had lower BMIs, she says. (Im calls the practice of sleeping in on the weekends “catch-up sleep.”)
The participants got an average of seven hours of sleep per night, with those who slept for longer on the weekends banking an extra 90 minutes to three hours on Saturdays and Sundays. Those who caught up on sleep over the weekend had an average BMI of 22.8, while those who did not had an average BMI of 23.1. (BMIs in the range of 18.5 to 24.9 are considered ‘healthy,’ according to the National Institutes of Health.) The change seems minor—but that difference of just 0.3 is statistically significant, making it clear that poor sleep can impact other aspects of your health, the researchers said.
How does missing out on sleep mess with your BMI? Those who don’t get enough sleep tend to have higher levels of the stress hormone cortisol (which can increase blood pressure and promote fat storage), and often crave high-fat, calorie-dense foods, Im says.
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When you sleep well throughout the week, or catch up on sleep over the weekend, you not only help your body function at its best throughout the day, but you also reduce your risk of weight gain and long-term health concerns like heart problems, she says.
Sounds like a plan, right? Just remember that since we all have individual sleep needs, there’s no one ‘dose’ of Zzz’s that will keep your waistline in check, Im says. To put things in perspective, the National Sleep Foundation recommends that adults get seven to nine hours of sleep per night—and in 2014, just 35 percent of Americans reported having ‘good’ sleep quality.
For the other 65 percent of us, making up for lost sleep on the weekends may be our best bet at getting out of sleep debt and keeping our weight—and health—in check. Getting a few extra hours on the weekend isn’t the ideal strategy (getting a full, quality sleep every night is the ideal, of course), but it can clearly make a difference, Im says. Just don’t try to re-stock on sleep by way of napping. “A nap is a fragmentation of sleep,” she says, meaning you can never fall into the deep sleep your body needs to recover from sleep loss.