How Many Calories Does Sleep Burn?
Roughly 45 to 60 calories an hour for most adults, or 350 to 500 over a night. It is not exercise, but it is a reminder that resting metabolism is most of what you burn each day.
In short
An average adult burns about 45 to 60 calories per hour asleep, which is slightly less than resting awake. Over eight hours that is roughly 350 to 500 calories, depending on body size. The figure comes from basal metabolic rate, the energy the body uses to keep organs running, which accounts for 60 to 70 percent of total daily burn in most people.
The question sounds like trivia and the answer is genuinely useful, because it reframes where calories go. Most people picture a day’s energy burn as mostly exercise and movement. It is mostly the cost of being alive.
The figure
Sleeping burns about 0.9 METs, slightly below the 1 MET of sitting quietly awake. One MET is roughly one calorie per kilogram of body weight per hour. So:
- A 60 kg person: about 54 calories an hour, around 430 over eight hours
- An 80 kg person: about 72 an hour, around 575 over eight hours
The commonly quoted range of 45 to 60 an hour covers most adults. Larger people burn more because there is more tissue to maintain.
Where it comes from
Basal metabolic rate: the energy cost of breathing, circulating blood, maintaining temperature, running the brain, repairing cells and everything else the body does without being asked. It runs continuously, awake or asleep, and it is the single largest component of daily energy use.
For a typical adult, basal metabolism is 60 to 70 percent of total daily burn. Digestion accounts for around 10 percent. Everything you would call activity, including exercise, is the remaining 20 to 30 percent.
That proportion surprises people. An hour in the gym is a real contribution and it is still smaller than the eight hours you spent unconscious.
Why the brain matters
The brain uses around 20 percent of resting energy despite being about 2 percent of body weight. During REM sleep, when dreaming happens, brain activity approaches waking levels. Deep slow-wave sleep is the cheapest phase. Over a night the phases average out to slightly below awake-and-resting.
What this is not
A weight-loss lever. You cannot sleep your way to a deficit, because the sleeping burn is already counted in every calorie calculator’s estimate of what you need. It is the baseline, not a bonus.
Where sleep does affect weight is through appetite. Restricting sleep to five hours reliably increases hunger and next-day intake in controlled studies, by a few hundred calories. Sleeping enough does not burn more; it stops you eating more.
The useful takeaway
If resting metabolism is two thirds of your energy use, the most powerful long-term lever is not the workout but the thing that raises the baseline: muscle. Muscle tissue costs more to maintain than fat, so adding it raises the burn during every hour of the day, including the eight you spend asleep. That is the real argument for strength training in any weight plan.
Common questions
Does sleeping more help you lose weight?
Not by burning calories, but adequate sleep does help. Short sleep raises hunger hormones and lowers fullness signals, and people restricted to five hours reliably eat more the next day. Sleeping enough makes a calorie deficit easier to hold.
Do you burn more calories in REM sleep?
Slightly. Brain activity in REM approaches waking levels and uses a little more glucose. The difference over a night is small, a few tens of calories.
Does a cold room make you burn more asleep?
Marginally. The body spends energy maintaining core temperature, and a cool room prompts a small increase. It is not a weight-loss strategy, though a room around 18°C does improve sleep quality.
Sources
Every factual claim above traces to one of these. Follow them rather than taking this article's word for it.
- Sleep and tiredness NHS
- Compendium of Physical Activities (MET values) Arizona State University
- Managing your weight NHS
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