Yes, even while you sleep your body is burning calories.
In fact, no matter what you're doing, your body is burning calories. It takes a significant amount of energy to power your whole body through each day, even without any added exercise or activity. So much do you burn while you sleep? That number depends on another number.
Most individuals burn between 19 to 26 calories per 30-minutes of sleeping. The number of calories burned will fluctuate depending on how much you weigh. For example, a 125-pound person will burn 38 calories per half hour, a 155-pound person will burn 44 calories per hour, and a 185-pound person will burn 52 calories per hour. The more you weigh, the more you burn during any activity, including sleep (see this handy energy expenditure chart from Harvard Health for more information on different activities and the corresponding calorie burn).
From these 30 minute timeframes, it's easy to understand that just sleeping takes a significant amount of energy! In fact, sleeping/napping accounts for nearly 19% of your total daily energy expenditure.
The amount that you burn during a night's rest appears to be solely based on your basal metabolic rate (BMR). Your BMR is essentially the amount of energy you require just to live- no additional activity required. Everything from your heart beating, to your liver functioning, takes energy and all of this is considered part of your BMR. In total, your BMR accounts for about 60% of your total calories burned in a single day.
Everyone's BMR is a little different depending on how much muscle (the more muscle you have, the higher your BMR because muscle takes quite a bit of energy upkeep) and/or how much you weigh (the lower your weight, the lower your BMR simply because you have less to keep alive). Another factor that may affect your BMR is if you're dieting for weight loss. Because weight loss requires you to eat less food, your body will often try to conserve energy by slowing your BMR down.
Although it's fun and even helpful to know how many calories you burn while you sleep, there are more important reasons to get enough shut-eye every night that contribute to your metabolic functioning and even the amount of food you consume throughout the day.
According to a study published in Obesity, individuals who only got 4-5 hours of sleep on average for several nights in a row burned up to 3% fewer calories the next day. The individuals that took part in the study did not return back to their normal metabolic functioning until they got 12 hours of sleep. This is because the body attempts to conserve energy when it feels like it is being threatened. Less sleep? You need your energy for the next day, so your BMR drops.
Because you're most likely feeling sluggish after a rough night of sleep, your body will also require you to consume more energy in order to function properly. Unfortunately, feeling sleepy can also trigger feelings of hunger, so most people consume over 400 calories more than what they actually need to in order to help them stay more alert and focused.
Getting enough sleep continues to be one of the key components in any successful wellness routine. And if weight loss is your goal, sleeping won't exactly help you lose weight- but, not getting enough could be very harmful to your long-term health. The best advice? Aim for 7 hours of sleep every night to help you power through your entire day successfully!