How Many Calories Do I Burn When I Sleep? | Nighttime Facts

Guide / By

Yes—during sleep your body burns about 0.9 kcal per kg per hour, which lands near 50–70 calories each hour for most adults.

Calories Burned During Sleep — Typical Ranges And Math

Sleeping still costs energy. A widely used benchmark lists sleeping at 0.9 MET, meaning your body uses 90% of the energy of quiet rest while you’re asleep. With the standard MET formula, calories per minute ≈ MET × 3.5 × weight(kg) ÷ 200. Multiply by 60 to get per hour.

To make it easy, kcal per hour of sleep ≈ 0.945 × weight(kg). If you prefer pounds, multiply body weight by about 0.428 for a quick hourly estimate. That’s why a 160-lb adult lands near 69 kcal per hour and ~550 kcal over eight hours.

Early Reference Table: Estimated Sleep Calories By Body Weight

This broad table uses the 0.9 MET for sleeping and assumes steady, comfortable room temperature and uninterrupted sleep.

Body Weight Calories Per Hour Calories In 8 Hours
110 lb (50 kg) ~47 kcal ~375 kcal
130 lb (59 kg) ~56 kcal ~450 kcal
150 lb (68 kg) ~64 kcal ~515 kcal
170 lb (77 kg) ~73 kcal ~585 kcal
190 lb (86 kg) ~82 kcal ~655 kcal
210 lb (95 kg) ~90 kcal ~720 kcal

The range shifts with real-world variables. Muscle mass pushes energy burn up; cold rooms, shivers, or vivid dreams can nudge it too. On the flip side, smaller bodies use fewer calories overnight.

Where Those Nighttime Calories Come From

Most of your 24-hour energy budget goes to basic functions such as breathing, circulation, and temperature regulation. That baseline is your basal metabolic rate (BMR). A medical overview from the Cleveland Clinic defines BMR as the calories needed for vital functions at rest and explains common drivers such as age, sex, and body composition (BMR overview).

Digestion adds a bump to daily expenditure called the thermic effect of food. Reviews in nutrition journals consistently place this near 10% of total daily energy on mixed diets (thermic effect of food). That component is lower during true fasting and higher after protein-rich meals.

How To Estimate Your Overnight Burn Accurately

There are two practical routes. First, use the MET math shown above. Second, start with a BMR estimate and then apply a sleep fraction. Because sleeping metabolism sits a touch below daytime resting levels, many coaches use ~85–95% of BMR per hour to approximate sleep energy use. That bracket fits most healthy adults and lines up with the observed MET for sleeping.

If you’ve never run your numbers, you can plug height, weight, age, and sex into a standard BMR equation such as Mifflin-St Jeor or Harris-Benedict. Then scale to your hours of sleep. This approach is handy when your body size sits outside the simple table above.

What Changes Your Sleep Calorie Burn?

Circadian timing. Resting energy isn’t flat across the 24-hour day. Lab work in Current Biology found resting energy lowest late at night and highest roughly half a day later, tracking body temperature rhythms (circadian phase study). If your schedule is irregular, that swing can alter nightly totals slightly.

Body composition. More lean mass raises energy needs even while you sleep. Two people at the same weight can differ if one carries more muscle and less fat.

Age and sex. BMR trends downward with age as lean mass declines. Men often burn a bit more than women of the same weight due to lean mass differences.

Room temperature and bedding. Cooler rooms increase heat-production demands. If you shiver, calories tick up. Overly warm rooms can also disturb sleep stages, which affects energy use indirectly.

Meal timing. Large late meals leave some digestive work during early sleep, modestly changing energy use for a few hours. The daily total from digestion still clusters near that ~10% share.

Worked Example: Turn BMR Into An Overnight Estimate

Say your BMR is 1,500 kcal/day. Per hour, that’s 1,500 ÷ 24 ≈ 62.5 kcal. Sleep tends to run a bit below that. Using 90%, your hourly sleep cost ≈ 56 kcal. For eight hours, you’d land near 450 kcal—similar to the MET-based estimate for a mid-sized adult.

How This Helps With Weight Goals

Nighttime burn won’t replace movement, but it matters when you want a realistic 24-hour picture. Many people overestimate daytime activity and forget that a large chunk of calories is already spoken for by baseline physiology. Reading up on energy spent burned per day doing nothing can sharpen that picture and keep expectations grounded.

Sleep Stages, Dreams, And Small Swings

Rapid eye movement (REM) features brain activity closer to wakefulness, with tiny bumps in energy use. Non-REM stages are a touch lower. Over a full night, those rises and dips average out for most people, so the hourly ranges in the table above remain useful.

Strength Training And Better Sleep Quality

Adding muscle raises BMR, and better sleep tends to support healthier appetite signals the next day. That’s a nice loop: train smart, sleep well, and you quietly burn a bit more even when you’re off the clock.

Room Temperature, Bedding, And Clothing

Cool but comfortable bedrooms often improve sleep quality for many people. If the room is too cold and you start to shiver, energy use rises, but sleep quality may fall. Target comfort first; steady, uninterrupted sleep usually wins over chasing small calorie differences.

Quick Math You Can Use Tonight

1) MET route: Convert weight to kilograms, then hourly sleep calories ≈ 0.945 × kg. Multiply by hours slept.

2) BMR route: Estimate BMR with a standard formula, take 85–95% of its hourly value, then multiply by hours asleep.

3) Sanity check: If your result falls near 400–560 kcal for eight hours and you’re an average-sized adult, you’re in the right ballpark.

Frequently Missed Nuances

“Why Do Online Numbers Differ?”

Different sites pick slightly different assumptions: 0.9 vs. 0.95 MET, eight vs. seven hours, or a different BMR formula. Small input changes create the spread you see across calculators.

“Does Eating Late Boost Night Burn?”

Yes, for a short window—because digesting food costs energy. Across a full day, that effect averages near one-tenth of total expenditure on mixed diets as shown in controlled chamber studies.

“Do Naps Count?”

Sure. A one-hour nap follows the same math. If you nap regularly, add that hour’s estimate to your daily total.

Second Reference Table: Factors That Nudge Sleep Energy

The entries below summarize direction and size for common variables. Use them to judge whether your own number might sit near the low or high end of the range.

Factor Typical Effect Practical Tip
More Muscle Higher BMR → higher sleep kcal Lift 2–4× weekly; recover well
Age Gradual decline with decades Preserve lean mass; move daily
Cold Room/Shivering Spikes energy if shivering starts Stay cool, not cold; layer bedding
Late Heavy Meal Small bump for a few hours Keep dinners balanced and calm
Circadian Low Lowest burn late biological night Keep a steady sleep schedule
Sleep Fragmentation Can lower quality and total time Cut caffeine late; keep a wind-down

Pulling It Together For Daily Planning

Use one method and stick with it for a few weeks so trends are comparable. Pair the number with your food log and step count. If your aim is maintenance, compare intake to a realistic 24-hour expenditure that includes sleep. If your aim is fat loss, let a modest deficit do the work while you guard sleep quality.

Want a bigger-picture plan after you’ve dialed in the night math? You can skim our primer on calories to maintain weight for a clean day-to-day target.

Method Notes And Assumptions

Why Use MET 0.9?

The Compendium of Physical Activities—an academic reference for energy costs—lists sleeping at the low end of intensity. Public-facing summaries repeat the 0.9 MET value for sleeping, which lines up with BMR-based back-calculations and lab data.

Why Mention Circadian Timing?

Resting energy varies with biological time. In a controlled-environment study, late-night values were lowest and afternoon values were highest. While the swings are modest, they explain why your nightly total isn’t exactly the same every day.

Credits And Sources

Primary references include the MET classification resource and peer-reviewed work on daily rhythms in resting energy, plus a medical overview of basal metabolism and a technical review on the thermic effect of food: