How Many Calories Do You Burn in Your Sleep? (Science-Based)

You burn about 40-55 calories per hour while sleeping, according to Harvard Health [1].

But this amount may vary from person to person depending on their basal metabolic rate (BMR) [2].

BMR is the energy used in performing essential functions such as breathing, temperature regulation, circulation, and cell growth and repair.

As you can derive from this definition, the human body uses sleep time to repair and regenerate, besides other normal functions.

And to do this effectively, body temperature drops, and breathing and metabolism slow down.

In case you’re wondering, metabolism is the process where your body converts food to energy so you can get things done.

According to research, a healthy person burns about 15% fewer calories while sleeping than during the day [3]. The same study also suggests that the calorie burn rate is at its minimum in the morning.

Now, to better understand the concept of sleep-time fat burning, we need to examine what may affect BMR during sleep.

Research shows men generally have a higher BMR than women [7]. This is partly because women generally have a slightly higher percentage of body fat and less muscle compared to men.

Additional studies have associated increased body fat in women with a low resting metabolic rate [8].

Genetics

Your genes can also influence how many calories you burn. You might have inherited a slow BMR from your family or, even worse, a metabolic disorder [9].

Studies show that Chinese and Indians generally have a lower BMR than Europeans. It could be due to dietary differences between the two races [10].

The same differences were seen in studies comparing African Americans to Caucasians, with reports showing the former having a lower RMR than the latter [11].

Physical Activity and Diet

Physical activity and diet also affect how many calories are burned, even when resting. Targeting muscle through exercise grows your muscles and makes them more metabolically active, which enables faster burning of calories.

On the other hand, eating certain meals like high protein foods for muscle gain require more energy to break down, so essentially the amount of energy you expend digesting factors in how many calories you burn at rest, which subsequently affects your body composition.

You can burn more calories while napping by consuming a proper diet, sleeping enough (7-9 hours), and exercising to lose weight regularly.

These activities improve your basal metabolic rate and enable you to burn more calories even while sleeping.

According to new research, an extra hour of sleep each night can help sleep-deprived people eat 270 fewer calories a day [12].

To burn more calories while sleeping, you have to take a keen interest in getting a good night’s sleep of about eight hours.

That's because sleep deprivation can cause a hormone surge that makes you crave high-calorie foods [13].

Yes, sleep stages affect calorie burning, with each stage burning different amounts of calories.

You burn the highest number of calories in the Rapid Eye Movement (REM) stage.

The REM sleep stage is the most energy intensive. It is the stage of sleep where the heart rate is the highest, and the brain has high activity patterns which demand more glucose [14].

Scientists investigating the REM stage found a link between short sleep duration and reduced REM stage [15].

“A lack of REM sleep may have adverse implications for physical and mental health.” - Jayne Leonard, Psychotherapist

Burning calories slows down in the third stage of sleep. In this stage, commonly known as deep sleep, respiration, core body temperature, brain activity, and heart rate are at a minimum [16]. The brain is also at its lowest activity.