Yes, you can actually burn more calories in your sleep — here's how, according to sleep experts

• You burn about 50 calories per hour while you sleep, which is approximately 400 a night.
• Most of your calorie-burning takes place during REM sleep, so extending REM may help burn more.

If you think physical activity is the only way you can burn calories, think again. Your body actually burns calories non-stop, even while you sleep.

Calories are essentially energy. Your body needs energy from calories in order to function and stay alive, both during your waking life and sleep.

The amount of calories that you burn just to keep your body going is called your basal metabolic rate (BMR), and this includes calories burned overnight.

Here's what you need to know about burning calories in your sleep and how to burn more.

How many calories do you burn while asleep?

You burn an average of about 50 calories per hour while you sleep, says Dr. Ramiz Fargo, sleep medicine specialist and chair of pulmonary and critical care medicine at Loma Linda University Health.

This means that if you sleep for eight hours, you'll burn about 400 calories — that's around 85% of the calories you would burn if you were awake and stationary.

Note: Your basal metabolic rate and how many calories you burn at rest varies based on factors such as your age, gender, genetics, activity level, and any underlying health conditions.

You burn calories when you're asleep because your body is still hard at work — even while you're unconscious. For example, your body still needs to tend to your heart, lung function, brain, liver, kidneys, and much more while you sleep, says Fargo.

"When your brain or any organ in your body is active, the cells in that organ need 'food' in the form of ATP that can be made indirectly from the calories you consume in your diet, such as carbohydrates like glucose," says Dr. Rajkumar Dasgupta, sleep medicine specialist and pulmonologist with Keck Medicine of USC.

Your brain is the organ that requires the most "food" in the form of glucose to function — particularly during rapid eye movement sleep (REM) sleep.

The brain is very busy during REM sleep. This is the stage of sleep where you're most likely to have vivid dreams, and it's also when memories are consolidated, Fargo says. In healthy adults, REM sleep accounts for about 20% to 25% of your total sleep.

The metabolism, or breakdown, of glucose increases in the second half of your night's sleep since you have increased REM sleep towards the morning, says Dasgupta. This means, as long as you're getting the recommended seven to nine hours of sleep each night, you'll burn the most calories during sleep in the latter half of your slumber.

Can I burn more calories while asleep?

It is possible to burn more calories while sleeping if you improve the quality and quantity of your sleep.

Dasgupta says the quality of your sleep includes how much REM sleep you're getting, since this is when you're burning the most calories, and quantity refers to how many hours.

You can improve the quality and quantity of your sleep by improving your sleep hygiene, which involves your habits surrounding bedtime, which have a great impact.

Here are eight sleep specialist-approved ways to improve your sleep hygiene and burn more calories in your sleep:

• Create the ideal sleep environment: Dasgupta says it's best to keep your room cool, quiet, and dark. The brain produces melatonin in response to darkness, so winding down in a dark bedroom can help your body know it's time to sleep. As for temperature, around 65º Fahrenheit is ideal.
• Limit light exposure before bed: Looking at bright screens like phones or computers that emit blue light can suppress melatonin production, Fargo says. If your melatonin production is suppressed, you may have trouble falling asleep. Therefore, Fargo recommends limiting the use of these devices before bed. Ideally, you should cut off use 30 minutes before bed.
• Keep a consistent sleep schedule: Being consistent with your bedtime and wake-up time is key, even on the weekends, says Dasgupta. Keeping a steady sleep schedule will help your body's internal clock, or circadian rhythm, stay predictable.
• Have a wind-down bedtime routine: Especially when you have stressful, busy days, it can be hard to shut your mind off and switch into sleep mode. Dasgupta recommends having a wind-down routine that includes relaxing activities that get you ready for bed such as reading, stretching, or meditating.
• Limit or avoid caffeine and alcohol intake: Caffeine and alcohol can both negatively affect your sleep, so you shouldn't have either too close to bedtime, Fargo says. Since caffeine can stay in your system for a while, it's recommended that you ideally stop drinking caffeine six hours before bed.
• Don't eat big meals too close to bed: Eating too much too close to bedtime can negatively affect sleep, Dasgupta says. Ideally, you should aim to cut off eating three hours before going to sleep.
• Exercise regularly: There are multiple reasons why regular exercise can help improve sleep and your calorie burn. First, Dasgupta says that exercise can help improve your sleep in and of itself. Additionally, if you build muscle from regular exercise, this is beneficial because muscles burn more calories than fat, Fargo says.
• Treat underlying health conditions: Various health conditions can impact your ability to get good quality sleep, such as obstructive sleep apnea, heart failure, and insomnia, says Dasgupta. It's important to treat any conditions that can be affecting your sleep –– not just to burn more calories, but to be in better health overall.

Insider's takeaway

You burn calories while you sleep because your body is utilizing calories and subsequent energy 24/7 to keep all your organs and bodily functions up and running. You burn the most calories while you sleep during the REM stage, when your brain is the most active.

If you want to burn more calories while you sleep, ensure that you're getting enough high-quality sleep, which also increases your chances of getting more REM sleep. Practicing good sleep hygiene and treating any underlying health conditions that might be affecting your shut-eye are great ways to increase your overnight caloric burn.