How many calories do you burn sleeping?

You spend about a third of your life asleep, and your body keeps spending energy the whole time. Your heart keeps beating, your lungs keep moving, your brain sorts through the day and your cells get on with repairs. If you're trying to lose weight, it's natural to wonder how much that night shift is worth, and whether more sleep could quietly do some of the work.

The numbers online don't agree. One article says 40 calories an hour, another says 75, and a calculator gives you a third answer. Most are estimates stacked on estimates. The better answer comes from people who slept in sealed rooms that measure every breath, and it shows what changes the number as well as what doesn't.

Below you'll find what those chamber studies found, how many calories you burn sleeping by body weight and by hours in bed, a simple way to work out your own figure, how the burn shifts between sleep stages, and what a short night does to the calories you burn and the calories you eat.

Does Sleeping Burn Calories?

Yes. Sleeping burns calories all night long, at nearly the same rate as lying awake in bed. Almost all of that energy is your BMR, short for basal metabolic rate: the cost of running your organs and keeping you alive at rest. Your brain alone accounts for about a fifth of it, as our post on whether thinking burns calories explains. Sleep trims that bill by about 5 percent at most across a whole night. It doesn't flip your body into a separate low-power mode.

So the answer to how many calories you burn while sleeping depends on the same things that set your BMR: your size, how much of you is muscle, your age and your sex. Fontvieille and colleagues (1994) measured 29 adults overnight in a sleep box built around a bed. Fat-free mass, fat mass, age, sex and ethnic background together explained 85 percent of the differences in sleeping metabolic rate between people.

Sleep is also the cheapest part of an ordinary day. On a day without exercise, most adults burn about 1.4 to 1.7 times their BMR in total, the range an FAO, WHO and UN University expert report gives for sedentary or lightly active lifestyles. Every waking activity, from cooking to climbing stairs, adds to the sleeping baseline.

Sleeping Metabolic Rate vs BMR: What Chamber Studies Found

The best measurements come from whole-room calorimeters. These are small sealed bedrooms where fresh air flows in at a known rate and sensors track how much oxygen you use and how much carbon dioxide you breathe out. From those two gases, researchers can work out your energy use minute by minute while you sleep in an ordinary bed.

Three of the largest studies compared a full night of sleep with BMR, which is measured in the morning while you lie awake, still and fasted:

• Goldberg and colleagues (1988) measured 80 healthy adults on 246 occasions. In the 40 lean adults, the whole night averaged 95 percent of BMR, and the lowest stretch of sleep averaged 88 percent.
• Seale and Conway (1999) measured 69 adults in a room-sized calorimeter at a US Department of Agriculture nutrition center in Maryland. Overnight energy use and BMR were identical, at about 1,640 calories a day, while the lowest hour of sleep ran about 10 percent lower.
• Kumahara and colleagues (2004) measured 94 Japanese adults and found that six hours of sleep averaged 95 percent of BMR, 93 percent in men and 97 percent in women.

Put together, a whole night of sleep runs at about 95 to 100 percent of your BMR. You'll often see the rule that sleep runs 15 percent below BMR. That figure fits the lowest point of the night, which Kumahara's team put at 80 to 90 percent of BMR in their review of earlier studies, rather than the average across eight hours.

Two more findings matter for real people. Goldberg's team saw higher overnight ratios in people with obesity, in late pregnancy and in people wired to heart monitors, and they put the difference down to more broken sleep. The ratio also varied between individuals, typically by about 8 points either side of the 95 percent average in the Japanese study. That's why any estimate, including the tables below, is a good guide rather than a measurement of you.

The night isn't flat, either. In a 2017 chamber study of 29 adults, Kayaba and colleagues found that energy use fell through the first half of sleep and then started rising again in the second half, before people woke up. Your metabolism starts picking up for the day before you open your eyes.

Calories Burned Sleeping by Body Weight

The table estimates how many calories you burn sleeping at different body weights. It uses the Mifflin-St Jeor equation from Mifflin and colleagues (1990), the equation our BMR calculator runs first. The reference sleepers are a woman 5 ft 4 in (163 cm) tall and a man 5 ft 9 in (175 cm) tall, both aged 40. Each BMR is multiplied by 0.95, the whole-night average from the chamber studies.

All figures are calories, rounded. To get closer to your own number, add about 1 calorie an hour for every 2 inches you're taller than the reference height, and about 2 calories an hour for every 10 years you're younger than 40. Take the same amounts off if you're shorter or older. A 25-year-old, 160-lb woman burns about 58 calories an hour asleep, and a 70-year-old of the same height and weight about 49.

Online calculators that multiply your weight by a MET value usually give higher numbers. The 2024 Adult Compendium of Physical Activities rates sleeping at 1.0 MET, the same as lying quietly awake, and the MET convention assumes 1 calorie per kilogram per hour. For a 160-lb (73 kg) adult that's 73 calories an hour, above both figures in the table's 160-lb row. Our post on whether standing burns calories explains why that convention runs high for most adults.

How many calories do you burn sleeping for 8 hours, 10 hours or 12 hours?

Multiply the hourly figure by the hours you sleep. Here's what that gives for four example sleepers:

A 12-hour sleep burns more than an 8-hour one only because it counts more hours. Per hour, a long sleep costs the same or slightly less, and those extra hours in bed replace time you'd otherwise spend awake and moving, which costs more.

How to calculate calories burned while sleeping

This is the method behind the tables, and it works for any body:

1. Estimate your BMR. Use the BMR calculator, or the Mifflin-St Jeor equation: 10 times your weight in kilograms, plus 6.25 times your height in centimeters, minus 5 times your age, then add 5 for men or subtract 161 for women.
2. Divide by 24 to get your BMR per hour.
3. Multiply by 0.95 for a full night of sleep.
4. Multiply by the hours you slept.

Here's an example. A 35-year-old woman who is 5 ft 6 in (168 cm) and weighs 150 lb (68 kg) has an estimated BMR of about 1,394 calories a day, or 58 an hour. Sleep brings that to about 55 an hour, so an 8-hour night burns about 440 calories.

Do You Burn More Calories When You Sleep or Awake?

Awake, but only a little if you're lying still. Lying awake in bed costs about your BMR, and a full night of sleep runs at about 95 percent of it. For a 160-lb adult the difference is roughly 3 calories an hour.

Getting up and staying up costs more. In a whole-room study by Jung and colleagues (2011), seven healthy young adults slept a normal night inside the calorimeter and then stayed awake through the next one. Energy use across the sleepless night was about 32 percent higher, 161 extra calories over eight hours, or about 20 an hour. Over 24 hours, the night without sleep cost about 134 extra calories. The authors compared that to a 68 kg (150 lb) adult walking about 3 km, just under 2 miles, at a moderate pace.

The Compendium puts everyday options on the same scale. Lying quietly in bed awake and sitting quietly both rate 1.0 MET, the same as sleeping. Desk work rates 1.3 METs, about a third more than sleep, and a slow walk at about 2 mph rates 2.8, nearly three times as much. Time in bed comes out almost even whether you're asleep or not, while any time on your feet pulls ahead fast.

Calories Burned in Each Sleep Stage

Through the night you cycle through light sleep (stages 1 and 2), deep slow-wave sleep and REM sleep, the stage when most vivid dreams happen. Each stage costs a slightly different amount, and the differences are small.

Deep sleep is the cheapest. In Fontvieille's sleep-box study, metabolic rate in deep sleep ran 39 calories a day below stage 2 and 51 a day below REM, measured as daily rates. Per hour of sleep, that's a gap of only about 1.5 to 2 calories. Katayose and colleagues (2009) found the same order in 12 men. REM sleep cost about 3.5 percent more than deep sleep, and the body burned more carbohydrate during REM.

Waking up is the expensive part of the night. In Kayaba's study, time awake in the middle of the night cost more than stage 2, deep and REM sleep. Jung's team also linked waking in the night to higher energy use, and they described the differences between the sleep stages themselves as small.

The brain explains much of the pattern. In a small PET-scan study, Maquet and colleagues (1990) found that the brain's glucose use fell by about 44 percent in deep sleep compared with wakefulness. In REM sleep it was as high as when awake. With the brain responsible for about a fifth of resting energy, a deep-sleep slowdown there shows up as a small dip in the whole-body numbers.

So you can't sleep your way to a bigger burn by chasing more deep sleep. If anything, deep sleep is the most economical part of the night. Protect it for recovery and for how you feel the next day.

What Short Sleep Does to Energy Balance

Short nights change both sides of your energy balance, the calories you burn and the calories you eat. The two sides move by very different amounts.

You burn a little more

Being awake costs more than being asleep, so cutting sleep raises your daily burn slightly. In Markwald and colleagues (2013), 16 young adults lived as inpatients in a research unit for about two weeks, with five days of 5 hours in bed and five days of 9. Short sleep raised total daily energy expenditure by about 5 percent, roughly 111 calories a day, mostly because of the extra hours awake. Shechter and colleagues (2013) found almost the same in 10 women who spent three days on either 4 or 8 hours of sleep. They burned 1,914 calories a day on short sleep against 1,822 on normal sleep, a gap of about 92.

You eat a lot more

The eating side moves further. In Markwald's study, people ate about 6 percent more on short sleep, ate 42 percent more after dinner and gained an average of 0.82 kg (1.8 lb) over the five short nights, even though they were burning more. When Al Khatib and colleagues (2017) pooled 11 lab studies, short sleep raised intake by about 385 calories a day, with no significant change in calories burned. Our page on whether 6 hours of sleep is enough covers that appetite research and the hunger hormones behind it.

The morning after a sleepless night

A whole night without sleep can also slow you down the next morning. In Benedict and colleagues (2011), 14 normal-weight men were measured the morning after either a normal night or a night awake. After the sleepless night, resting energy use was about 5 percent lower and energy use after breakfast about 20 percent lower. Jung's team saw a similar rebound. On the recovery day, 24-hour burn fell about 5 percent below normal, roughly 96 calories.

Add it up and the arithmetic leans one way. A short night buys roughly 90 to 135 extra calories burned, about the cost of a 2-mile walk, while the pooled studies find people eat about 385 more. That's why short sleep and weight gain keep turning up together in this research. It's a predictable response to being tired with food within reach, and planning for it works better than blaming yourself.

Does sleeping more help you lose weight?

Sleeping longer burns slightly fewer calories than staying up, but it can cut what you eat. In a 2022 randomized trial by Tasali and colleagues, adults with overweight who extended their sleep by about 1.2 hours a night ate about 270 fewer calories a day. Our review of sleep debt recovery covers that trial and how to rebuild your sleep after a bad week.

Do You Lose Weight While You Sleep?

Most people weigh a little less in the morning than at bedtime, and it's tempting to read that as fat burned overnight. Most of the drop is water. You lose water vapor with every breath and through your skin all night, and a trip to the bathroom does the rest.

The fuel you burn weighs far less than the scale change suggests. When Meerman and Brown (2014) traced the atoms in burned fat, 84 percent left the body as carbon dioxide through the lungs and 16 percent as water. A 160-lb woman burns about 440 calories in an eight-hour night. Even if every one of those calories came from fat, that's only about 50 grams, under 2 ounces. In reality the overnight fuel is a mix of fat and carbohydrate.

Can You Burn More Calories While You Sleep?

Only a little, and most of the levers sit outside the bedroom:

• More muscle. Fat-free mass is one of the main drivers of sleeping metabolic rate in the chamber studies, so building muscle raises it slightly. Our post on whether muscle burns fat puts the gain at about 6 calories a day for each pound of muscle at rest.
• A cooler bedroom. Mild cold can raise energy use through brown fat. Our article on whether being cold burns calories covers how much, including a month-long trial of people sleeping in a cool room.
• Enough sleep. It won't raise the overnight burn, but it keeps your next-day appetite and energy in a better place, which matters far more for your weight.

If losing weight is the goal, the useful levers are in your waking hours: regular movement, strength training, what and how much you eat, and enough sleep to keep your appetite steady. Our comparison of the best workout apps for weight loss ranks seven apps on what exercise adds to fat loss: showing up, keeping muscle and burning energy.

What This Means for You

Your body burns somewhere around 380 to 650 calories every night with no effort from you, and there's little to gain from trying to push that number up. Body size and muscle set most of it. What sleep does decide is how the next day goes: how hungry you feel, how much you snack after dinner and how much energy you bring to a workout.

So treat sleep as part of your plan rather than as a fat burner. Aim for the seven or more hours that adult sleep guidelines recommend, put your workouts at a time you'll actually keep, and let the calories you can change come from your waking hours. FitCraft's 3D AI coaches lead bodyweight and dumbbell workouts you can do at home, and streaks reward each day you show up. As Sarah, a FitCraft user, put it: “First app that made exercise feel like something I chose, not forced.”