When you're asleep, your body is actively working on cell repair and growth and your brain is processing information. All these do add up to a significant calorie burn.
It depends on your body weight, the amount of time you're asleep, and your body temperature, says Cathy Posey, RD, a blogger, and nutrition coach from happyhouseful.com. She offers a simple way to approximate how many calories you burn in your sleep: "On average, people burn about .42 calories an hour per pound of body weight while they sleep," she says. So, multiply your weight in pounds by .42. (We won't judge if you use a calculator.) Then, multiply that amount by the number of hours you're asleep. So, if you weigh 155 pounds and you sleep for eight hours, how many calories do you burn sleeping? About 520. That's about the same amount as what you'd burn during a one-hour jog, says Fish.
Just don't expect sleeping to replace that hour of exercise. After all, that's your sleeping body burning the number of calories in eight hours that your awake body could burn in one.
Some other ways to burn more calories while you sleep are to wear cooler pajamas or even sleep in the buff. "Sleeping cooler, which is easier in your birthday suit, can boost metabolism and aid in weight loss," Terry Cralle, RN, clinical sleep educator, and Saatva sleep expert, tells RD.com. A National Institutes of Health study found that having a cooler body temperature while you sleep can help boost your body's calorie-burning cells and metabolism. And Posey recommends making sure any meals you eat in the evening are on the lighter side. Posey also says that regular exercise can keep your body at optimal calorie-burning levels (although exercising right before bedtime might prevent you from sleeping deeply). Find out some more ways you can literally lose weight in your sleep.
If you've found yourself wondering how many calories you burn in your sleep before, you've probably come across the myth that sleeping burns more calories than watching television. Well, that isn't true—though it's pretty close. "On average, when asleep, a person burns roughly 90 percent of the calories they would if they were sitting on the couch watching television," Fish says. So, yes, watching the tube does burn slightly more calories—but that doesn't mean it's a healthy habit. The real issue with watching TV is that you often get hungry and reach for something to snack on—something that's not the best for you, nutritionally. Screen-time calorie consumption can easily add up and negate the massive calorie burn. Here are 25 more myths about weight loss you need to stop believing.