During sleep, the body typically expends about 50–70 calories per hour, driven mostly by basal functions like breathing and repair.
Per-Hour Burn
Typical Night
Upper Range
Basic Method
- Use a BMR formula
- Multiply by a sleep factor
- Scale to your hours
Quick math
Better Estimate
- Add a weight range
- Account for age/sex
- Include usual sleep length
More context
Best Detail
- Use measured RMR
- Adjust for 5–15% drop
- Track weekly averages
Most accurate
Calories Burned During Sleep Per Hour: A Clear Method
Overnight energy use comes from the same engine that runs your day: basal metabolism. Organs and tissues keep working while you’re off your feet, so the meter never hits zero. A practical way to estimate your nightly total is to start with a resting formula, then trim it slightly for the drop that arrives during slumber.
The widely used Mifflin–St Jeor approach estimates resting energy from age, sex, weight, and height. Research shows it performs well across many body types, and it maps neatly to real-world measurements. Once you have that resting number, apply a sleep factor in the ballpark of 0.90–0.95 to reflect the modest dip during the night. Finally, scale to your time in bed by multiplying by your hours and dividing by 24.
Quick Formula You Can Use
Night Calories ≈ BMR × Sleep Factor × (Hours Slept ÷ 24)
- BMR: from a trusted equation such as Mifflin–St Jeor.
- Sleep Factor: 0.90–0.95 is a practical range based on studies reporting a small decline in metabolic rate during sleep.
- Hours Slept: your usual night (round to the nearest quarter hour for easy math).
Broad Reference Table (Per Hour And Per 8 Hours)
This table shows typical per-hour and 8-hour totals for a range of body weights when sleep is 7–8 hours and the sleep factor sits near the middle of the range. These are ballparks, not medical prescriptions.
| Body Weight | Per-Hour During Sleep (kcal) | 8-Hour Total (kcal) |
|---|---|---|
| 50 kg (110 lb) | ~48–54 | ~385–430 |
| 60 kg (132 lb) | ~52–60 | ~415–480 |
| 70 kg (154 lb) | ~56–66 | ~450–525 |
| 80 kg (176 lb) | ~60–72 | ~480–575 |
| 90 kg (198 lb) | ~64–77 | ~510–615 |
| 100 kg (220 lb) | ~68–82 | ~545–655 |
| 110 kg (242 lb) | ~72–86 | ~575–690 |
| 120 kg (265 lb) | ~76–90 | ~605–720 |
Notice how the hourly rate climbs with size. Age, sex, and height pull the estimate up or down too, and your usual food schedule adds a small bump from digestion. The bump from digestion, often called the thermic effect of food, runs near one-tenth of daily energy on average according to an NIH overview on energy expenditure. For a late dinner, that slice can slightly raise your first hours in bed.
Why Sleep Calories Aren’t Zero
Even at rest, the brain, heart, liver, kidneys, and muscles need energy. During the night, the mix of fuels shifts and the pace eases a bit. Reviews of sleep physiology show a modest decline in energy use during typical nights, often in the single-digit to low double-digit percent range compared with quiet wakefulness. That drop reflects lower core temperature, slower breathing, and reduced muscle tone.
Stages matter too. Deep stages tilt toward the low end, while REM periods edge closer to resting wakefulness because the brain is active. Cycle by cycle, that averages out to the small reduction most people see.
Method: From Resting Energy To Nightly Burn
Here’s a practical walk-through using an example. Say your BMR comes to 1,500 kcal/day. With a sleep factor of 0.92 and 7.5 hours in bed, the math is:
Night Calories ≈ 1,500 × 0.92 × (7.5 ÷ 24) ≈ 431 kcal
The same setup with a 0.95 factor and 8 hours gives 475 kcal. These are realistic spans for many adults. If you’ve measured resting energy in a lab, swap that value in to tighten the estimate.
Context: RMR, Meals, And Sleep Loss
Resting energy forms the bulk of daily burn, and diets influence it at the edges. Digesting and processing meals costs energy, and most references place that share near ten percent of daily total. Timing shifts where that energy lands across the day and night. Sleep loss adds another twist: some trials show a small rise in 24-hour expenditure, but that uptick is usually paired with larger increases in intake later on, which can erase the gain.
Estimating Your Own Nightly Burn
You don’t need a lab to land in the right neighborhood. A calculator based on the Mifflin–St Jeor math will get you close. Plug in age, sex, height, and weight, jot down the resting number, then run the short formula from earlier. The sleep factor sets the slider. If you run warm at night, or you’re a restless sleeper, use 0.95. If you tend to feel cool and sleep deeply, use 0.90.
Once you have a nightly number, sanity-check it against your day. If your daily maintenance calories hover near 2,000, an overnight slice around 400–500 makes sense for typical sleep lengths.
Where An Internal Deep-Dive Helps
Understanding your daytime baseline smooths the estimate. After you’ve set your plan for calories burned burned while resting, the night math becomes simple arithmetic.
Sleep Stages And Energy Use
Sleep cycles repeat in waves. As your brain shifts between light stages, deeper slow-wave periods, and REM, the balance of fuels and heat generation moves with it. That’s why a single point estimate can’t capture every minute. Still, when you average several nights, the pattern settles into a tight range for most healthy adults.
| Stage Or Factor | Energy Use Trend | Notes |
|---|---|---|
| Light NREM | Near baseline | Gentle drop from quiet wakefulness |
| Deep NREM | Lower end | Cooler core temp and slower breathing |
| REM | Higher end | Active brain raises demand |
| Late Meals | Slight bump | Small lift from digestion (TEF ~10% of daily) |
| Short Sleep | Small shift | Tiny 24-h change; often outweighed by higher intake |
| Muscle Mass | Higher baseline | More lean tissue lifts resting burn all day and night |
What Moves The Number Up Or Down
Body Size and Composition
Lean tissue consumes more energy than fat tissue. More muscle means a higher baseline around the clock, which nudges nightly burn upward. That’s why resistance training can change the picture over weeks and months, even when weight stays stable.
Age, Sex, And Height
These inputs affect BMR in all formulas. Taller frames and younger ages trend higher. The math bakes that in and carries through to your night estimate.
Room Temperature And Bedding
Cooler rooms can raise the cost of heat production a touch, especially for those who sleep with light covers. It’s not a large swing, but it’s one reason your per-hour range isn’t a single number.
Food Timing
Eating close to bedtime shifts some of the meal-processing cost into the early part of the night. The total daily cost doesn’t change much; the curve simply tilts toward the first cycles.
Sample Walk-Throughs
Smaller Body, Deep Sleeper
A 55-kg adult, 1.65 m tall, BMR near 1,280 kcal/day. Deep sleeper, cool room, 8 hours. Use a sleep factor of 0.90: 1,280 × 0.90 × (8 ÷ 24) ≈ 384 kcal. Per hour lands near 48 kcal.
Larger Body, Warmer Sleeper
A 95-kg adult, 1.80 m tall, BMR near 1,950 kcal/day. Warmer sleeper, some tossing, 7 hours. Use 0.95: 1,950 × 0.95 × (7 ÷ 24) ≈ 541 kcal. Per hour sits close to 77 kcal.
What Science Says About The Night Drop
Peer-reviewed overviews report a modest reduction in sleeping energy compared with quiet wakefulness. That reduction often falls between five and fifteen percent across healthy adults. Reviews also show that curtailing sleep can nudge 24-hour expenditure a little, yet appetite tends to climb more, which explains weight-gain patterns seen with chronic short nights.
For an evidence base behind the math, see the original paper introducing the Mifflin–St Jeor equation and the NIH textbook chapter on the small daily share from meal processing. Both give you the building blocks you need to make a clear estimate without guesswork.
Practical Tips To Refine Your Estimate
Average A Few Nights
Single nights vary. Calculate three to five nights and keep the middle value. That smooths late dinners, unusually cool rooms, and restless cycles.
Use Consistent Inputs
Stick to one equation and one sleep factor while you experiment. If your weight changes by more than a few kilos, re-run the numbers.
Sync With Your Day Plan
If you watch maintenance calories, line up the night slice with your overall plan so totals feel steady across the week. That balance tends to be easier to live with than day-to-day swings.
Frequently Misunderstood Points
“Longer Nights Always Burn Way More”
Longer nights add time, not a big spike in rate. Doubling hours doesn’t double the per-hour pace, so totals rise linearly with the clock, not exponentially.
“Skipping Sleep Burns Fat”
Short nights can lift 24-hour expenditure a little, yet late-night snacking often cancels that out. The long game favors consistent, sufficient sleep rather than trimming hours for a tiny bump.
Where To Learn More
The core math rests on well-cited methods. The Mifflin–St Jeor equation gives you a solid baseline. An NIH chapter on energy expenditure outlines how digestion contributes near ten percent of the day (thermic effect overview). Together they explain why your per-hour rate during the night usually sits just below quiet daytime rest.
Ready To Keep Going?
Want a longer plan beyond sleep math? A gentle next read is daily calorie targets—handy when you’re shaping meals around steady energy needs.