Most articles give you one number: "about 50 calories an hour." That is a reasonable average, but it hides a lot. A small, older woman and a tall, young, muscular man can differ by 30 calories or more per hour of sleep, and over a full night that becomes a gap of a couple of hundred calories. This guide shows you how to estimate the calories you burn sleeping from your own BMR, explains why the popular "multiply by 0.85" shortcut probably underestimates it, and looks at what sleep actually does (and does not do) for your daily calorie balance.
Quick answer: most adults burn roughly 40 to 85 calories per hour asleep, or about 300 to 650 calories over a 7 to 8 hour night. Your number is close to your basal metabolic rate (BMR) divided by 24, multiplied by the hours you sleep, then trimmed by around 5%.
Why you burn calories while you sleep
Sleep is not "off mode." While you are asleep, your heart keeps pumping, your lungs keep moving air, your brain stays active (especially during REM sleep), your body holds its core temperature, and cells keep repairing and rebuilding tissue. All of that costs energy. This baseline cost of staying alive is what your basal metabolic rate measures, and it is the single biggest part of the calories most people burn in a day.
What sleep removes is almost everything else: no walking, no fidgeting, no standing, very little digestion late in the night. That is why the calories burned while sleeping sit very close to BMR itself, rather than to your total daily energy expenditure (TDEE).
The quick formula for calories burned sleeping
You only need two inputs: your BMR and how long you actually sleep.
Calories burned sleeping ≈ (BMR ÷ 24) × hours asleep × 0.95
Step by step:
- Estimate your BMR. The Mifflin-St Jeor equation is a sensible default for most adults: for men, 10 × weight (kg) + 6.25 × height (cm) − 5 × age + 5; for women, the same but −161 at the end. If you know your body-fat percentage, Katch-McArdle can work better. Our guide to all five BMR equations walks through each one.
- Divide by 24 to get your hourly basal burn.
- Multiply by the hours you actually sleep, not the hours you spend in bed.
- Multiply by about 0.95 to account for the small dip in metabolic rate during sleep compared with a measured BMR.
Why 0.95 and not 0.85?
Many popular articles tell you to cut BMR by 15% for sleep. That number traces back to a real observation: a widely cited review in the International Journal of Endocrinology notes that during normal sleep "the metabolic rate reduces by around 15%" and reaches a minimum in the morning (Sharma & Kavuru, 2010). The catch is the comparison point. That drop is relative to your metabolism while awake, not relative to BMR, which is already measured in a fully rested, fasted, lying-down state.
When researchers compare the two directly, the gap is much smaller. In a respiratory-chamber study of 94 healthy adults, sleeping metabolic rate averaged 1,416 kcal/day against a BMR of 1,492 kcal/day, so sleep ran at about 95% of BMR on average, with men around 93% and women around 97% (Kumahara et al., 2004). The ratio varied from person to person, but none of age, weight, BMI or body fat predicted it.
So applying a 15% cut to a BMR estimate double-counts the "resting" discount and lands too low for most people. A 5% trim is a closer starting point. In practice the difference is only 40 to 70 calories a night, which is well inside the error of any BMR formula, but if you are going to use a shortcut, use the one that matches the evidence.
Calories burned sleeping: worked examples
The table below uses Mifflin-St Jeor BMR estimates for five example adults. It shows the hourly rate during sleep and totals for a 7-hour and an 8-hour night, plus what the common 0.85 shortcut would give for 8 hours.
| Example person | Estimated BMR (kcal/day) | Per hour asleep | 7 hours | 8 hours | 8 h with 0.85 shortcut |
|---|---|---|---|---|---|
| Woman, 30, 165 cm, 60 kg | 1,320 | ~52 | ~366 | ~418 | ~374 |
| Woman, 50, 162 cm, 75 kg | 1,352 | ~53 | ~374 | ~428 | ~383 |
| Woman, 65, 158 cm, 68 kg | 1,182 | ~47 | ~327 | ~374 | ~335 |
| Man, 35, 178 cm, 80 kg | 1,742 | ~69 | ~483 | ~552 | ~494 |
| Man, 25, 185 cm, 95 kg | 1,986 | ~79 | ~550 | ~629 | ~563 |
For comparison, Harvard Health Publishing's activity chart lists sleeping at about 19, 22 and 26 calories per 30 minutes for people weighing 125, 155 and 185 pounds, which works out to roughly 38 to 52 calories an hour (Harvard Health). Chart values like these are based on body weight alone, so they cannot reflect differences in height, age, sex or muscle, which is exactly why a BMR-based estimate is more personal.
What changes how many calories you burn asleep
Body size and muscle
Larger bodies have more tissue to maintain, so they burn more at rest. Lean tissue, organs in particular, is more metabolically active than fat tissue. Muscle helps too, though its effect per kilogram is smaller than many fitness posts claim; we break down the real numbers in does muscle really burn 50 calories a day?
Age and sex
BMR equations subtract calories as age rises, and men usually have a higher BMR at the same weight because, on average, they carry more lean mass. Both effects carry straight through to your overnight burn.
Sleep stages and time of night
Energy use is not flat across the night. In a whole-body calorimeter study of 12 men, energy expenditure fell through the first half of the night, reached its low point and stayed fairly stable until waking, while REM periods showed small increases in energy expenditure (Katayose et al., 2009, Metabolism). These swings matter for physiology, but you cannot meaningfully "game" them for weight control.
Late meals
Digestion has its own cost, called the thermic effect of food. A large dinner shortly before bed nudges energy use up for the first hours of sleep. The effect is modest; see how many calories eating burns for the honest math.
Bedroom temperature and health factors
A cooler room asks your body to work a little harder to stay warm, and illness, fever, thyroid conditions and some medications can all shift resting metabolism. If your resting metabolism seems very different from what formulas predict, that is a conversation for a doctor, not something to fix by changing your sleep.
Does sleeping less burn more calories?
Technically, yes, a little, because being awake costs more than being asleep. In a carefully controlled inpatient study, five days of restricted sleep raised total daily energy expenditure by about 5%. But the same participants ate more than enough to cancel that out, especially in after-dinner snacks, and gained an average of about 0.8 kg over the five days (Markwald et al., 2013, PNAS). The University of Colorado summary put it simply: participants burned about 5% more energy but consumed about 6% more calories (CU Boulder Today).
The practical lesson is the opposite of what the arithmetic suggests: cutting sleep is not a calorie strategy. For most people, enough good-quality sleep makes appetite and food choices easier to manage, which matters far more than the few dozen calories an extra hour awake might burn.
Can you burn more calories while sleeping?
Not in any dramatic way. Because your overnight burn tracks your BMR, the only levers are the same slow ones that affect resting metabolism over months:
- Keep or build lean mass with regular resistance training and enough protein. Our protein per day guide covers sensible targets.
- Stay active during the day. Daytime movement does not raise your sleeping burn much, but it raises your total burn a lot. See NEAT and daily steps.
- Protect sleep duration and regularity so hunger signals stay easier to manage the next day.
- Be sceptical of "burn fat while you sleep" products. Supplements, teas and gadgets sold with that promise are not a substitute for the basics, and claims of large overnight burns are not supported by the studies above.
How to use this number in your daily calorie plan
Here is the key point that most "calories burned sleeping" articles skip: your sleeping calories are already inside your BMR and TDEE. If you calculate your TDEE and then add 400 to 600 "sleep calories" on top, you count them twice and overestimate what you can eat.
Where the overnight figure is genuinely useful:
- Sanity-checking a wearable. If your watch claims you burned 900 calories in eight hours of sleep but your BMR is about 1,400, the device is likely overestimating.
- Understanding your baseline. Seeing that roughly a fifth to a quarter of your daily energy is spent while you sleep makes it clear why BMR is the foundation of any calorie estimate.
- Building TDEE from parts. Sleep hours at about 0.95 × BMR per hour, plus waking hours at your activity level. If you prefer the simple route, use an activity multiplier instead.
Whatever method you choose, treat the result as a starting point, then adjust based on how your weight trend actually moves over two to four weeks. Our guide on how many calories to eat to lose weight shows how to do that adjustment carefully.
Common mistakes
- Using time in bed instead of time asleep. Eight hours in bed is often closer to seven hours of sleep.
- Applying a 15% cut to a BMR estimate. That discount describes the drop from waking metabolism, not from BMR.
- Adding sleep calories on top of TDEE. They are already included.
- Treating any estimate as exact. BMR formulas can be off by 10% or more for an individual; only indirect calorimetry measures it directly. See how to measure your BMR.
FAQ
How many calories do you burn sleeping for 8 hours?
Most adults burn somewhere around 300 to 650 calories over eight hours of sleep. Smaller and older people sit toward the low end, larger and younger people toward the high end. Use (BMR ÷ 24) × 8 × 0.95 for a personal estimate.
Do you burn more calories sleeping or sitting?
Sitting quietly burns slightly more. Harvard Health's chart lists reading while seated at about 34 to 47 calories per 30 minutes versus about 19 to 26 for sleeping, depending on body weight.
Do you burn more calories during REM sleep?
A little. Calorimeter studies show small rises in energy expenditure during REM compared with deep non-REM sleep, but the difference is too small to change your daily calorie balance in a meaningful way.
Is calories burned sleeping the same as BMR?
Close, but not identical. Measured sleeping metabolic rate averaged about 95% of BMR in a chamber study of 94 adults, with individual variation.
Does sleeping more help with weight loss?
Extra sleep does not burn extra calories in itself; being asleep burns slightly less than being awake. However, short sleep has been linked to eating more, so adequate sleep can make a calorie plan easier to stick to.
Why does my fitness tracker show so many calories burned overnight?
Many trackers estimate resting burn from your profile and heart rate, and their totals can be noticeably off. Compare the overnight number with your own BMR-based estimate; if it is far higher, trust the trend of your body weight over the device.
Bottom line
Each hour you sleep, you burn roughly your hourly BMR (BMR ÷ 24), minus about 5%. For most adults that is about 40 to 85 calories an hour and a few hundred calories a night. It is a useful number for understanding your metabolism and checking a wearable, but it is already part of your BMR and TDEE, and sleeping less is not a way to burn more. Calculate your BMR, keep sleep regular, and let your real-world weight trend guide your adjustments.
This article is general educational information, not medical advice. Calorie and BMR figures are estimates. If you have a health condition, are pregnant, or are planning a significant change in diet or exercise, talk to a qualified healthcare professional.
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