You don't just burn calories while you are awake and moving. Studies show mental activity comprises about 20% of your resting metabolic rate, or the calories you burn without physically moving.
Your brain continues to do this while you sleep. In fact, your brain is working just as hard during REM sleep as it is while you’re awake.
People can burn anywhere between 300 and 700 calories each night but the exact number depends on a range of factors, including your body's Basal Metabolic Rate and the quality of your sleep. Sleep expert Jasmin Lee at eachnight.com says there a few steps to determining the number of calories you burn while sleeping.
The first thing to establish is your Basal Metabolic Rate or BMR. Also known as your body’s metabolism, BMR is the number of calories needed to keep your body functioning at rest. BMR varies based on an individual’s weight, gender, and age.
Another factor when calculating your basal metabolic rate is your average daily movement. That means how much you’re regularly moving. Unfortunately, a one-time workout won’t provide an accurate metabolic rate change in your calculation.
When you’re sleeping, your body’s basal metabolic rate is 85-95% of your normal rate during the day. To find out how many calories your body needs during sleep, first determine your daily BMR, which you can do by using an online calculator.
Since this is for a 24-hour day, divide this number by 24 for your hourly metabolic rate. Then multiply that by .85 (since your body functions at 85% during sleep). Multiply that by the number of hours slept. And there you have it — calories burned while sleeping. Here’s the formula:
BMR ÷ 24= hourly BMR
Hourly BMR × .85 × hours slept = calories burned while sleeping
Average calories burned during 8 hours of sleep
If you don’t like maths, not to worry. Examining some average numbers can be a good place to start. Consider these examples for calories burned during eight hours of sleep:
30-year-old, 110 lb female: 406 calories
30-year-old, 180 lb male: 601 calories
50-year-old, 110 lb female: 376 calories
50-year-old, 180 lb male: 558 calories
40-year-old, 130 lb female: 424 calories
40-year-old, 200 lb male: 619 calories
As you can see, the amount of calories burned decreases with age and increases with body weight. Metabolism slows with age, so it comes as no surprise that we see a decrease in caloric burn. A person with a larger body will also burn more calories to function.
How to burn more calories during sleep
There are a few ways to increase your calorie burn while you sleep, Jasmine says. The first key is to get a better night’s rest, ensuring you have REM (rapid eye movement) periods in your sleep cycle.
This is when your brain is most active and burns the most calories. This is because your brain is burning more oxygen when it’s working hard during this sleep cycle.
Exercise is important to maintaining healthy body weight, and it can improve your sleep quality. However Jasmine says exercising that day won’t actually help you burn more calories while you’re sleeping - but maintaining an active lifestyle regularly can affect your BMR in a positive way).
The number of calories your body needs daily depends on your age, biological gender, and average lifestyle activity. Women who work desk jobs and exercise very little usually burn 1,600 calories per day.
On the other hand, men who lead sedentary lifestyles and exercise minimally usually burn around 2,000 calories per day. Even things as little as tapping your toes can burn calories - and the best way to naturally burn calories is to add movement into daily activities, like choosing to walk vs drive.
