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Last Updated January 8, 2026
Sleep feels like a full stop at the end of the day. You lie down, close your eyes, and everything slows. It may seem like your body switches off, but it never truly does. While you sleep, essential work continues in the background. Your body keeps itself running and focused on repair. That quiet effort still requires energy. This article explains how many calories you burn while sleeping and why sleep still matters for metabolism, even though it is not a shortcut to fat loss.
Key Takeaways:
Yes, you do burn calories while you sleep.
Your body never fully shuts down. While you are asleep, it continues to power essential functions like breathing, circulating blood, repairing tissues, regulating hormones, and maintaining body temperature. All of this requires energy, and energy comes from calories.
That said, the number of calories burned during sleep is lower than when you are awake and moving around. Your metabolism slows down, but it does not stop.
For most adults, calorie burn during sleep falls into a predictable range. On average, people burn about 40 to 55 calories per hour while sleeping. Over a full night, that adds up more than many expect.
Although individual numbers vary, sleep-related calorie burn falls within predictable ranges for most adults.
| Time Asleep | Estimated Calories Burned |
|---|---|
| 1 hour | 40–55 calories |
| 6 hours | 240–420 calories |
| 7 hours | 280–490 calories |
| 8 hours | 320–560 calories |
| 9 hours | 360–630 calories |
These estimates assume a healthy adult with an average metabolic rate. Athletes, people with higher muscle mass, and those recovering from illness may fall on the higher end.
Body weight plays a direct role in energy use. A larger body requires more energy to sustain circulation, respiration, temperature control, etc.
| Body Weight | Calories Burned per Hour |
|---|---|
| 50 kg (110 lb) | 35–45 |
| 60 kg (132 lb) | 40–50 |
| 70 kg (154 lb) | 45–55 |
| 80 kg (176 lb) | 50–65 |
| 90 kg (198 lb) | 55–70 |
| 100 kg (220 lb) | 60–75 |
These values assume similar body composition. Two people who weigh the same can still burn different amounts of energy depending on their muscle mass.
Calculating an exact number is difficult, but you can get a reasonable estimate.
The most accurate way to measure basal metabolic rate involves a calorimeter in a lab setting. This test measures oxygen intake and carbon dioxide output to determine how much energy your body burns at rest. Because it is expensive and inconvenient, it is not practical for most people.
A simpler option is to use an equation.
Using the Harris-Benedict Equation:
The Harris-Benedict equation estimates your basal metabolic rate based on weight, height, age, and sex.
This result estimates how many calories your body burns over a full day while awake at rest.
To estimate calories burned during sleep:
This gives you a rough hourly sleep calorie burn.
Equations do not account for everything.
They do not consider genetics, hormone levels, muscle-to-fat ratio, or underlying health conditions. They also cannot fully reflect how sleep stages affect calorie burn.
Body mass index (BMI) is sometimes used to estimate body composition, but it has limitations. For example, it does not work well for pregnant individuals. Nor does it work accurately for athletes or people with atypical body compositions.
So, use these numbers as a guide, not a rule.
Sleep moves through cycles that include light sleep, deep sleep, and REM sleep. Each stage serves a different purpose.
Deep sleep focuses on physical repair, immune support, and growth hormone release. REM sleep supports brain activity, learning, and emotional processing. Light sleep bridges transitions between stages.
Energy use shifts slightly between stages. REM sleep tends to use more energy than deep sleep due to higher brain activity. Deep sleep lowers heart rate and breathing. Over a full night, these variations balance out. Total sleep duration matters far more than time spent in any single stage.
Two people can sleep the same number of hours and still burn very different amounts of energy. That difference comes down to a mix of personal traits and sleep conditions that influence how hard the body has to work while at rest.
Body composition plays one of the biggest roles in sleep calorie burn. Muscle tissue is metabolically active, meaning it requires energy even when you are completely still. Fat tissue, by contrast, needs very little energy to maintain itself.
This is why two people who weigh the same can burn different numbers of calories during sleep. The person with more lean muscle mass will generally burn more calories overnight. Strength training does not turn sleep into a high-calorie activity, but it does raise your baseline energy needs around the clock, including while you sleep.
As people age, their metabolism tends to slow. This is partly due to natural muscle loss that occurs over time, especially if strength training is not part of daily life. Hormonal shifts also affect how efficiently the body uses energy at rest.
Because of this, calorie burn during sleep often decreases gradually with age. The change is not sudden, and it does not mean sleep becomes less important. In fact, older adults often benefit even more from consistent, high-quality sleep to support metabolic health and muscle preservation.
On average, men burn more calories at rest than women. This difference is largely explained by body composition. Men typically carry more muscle mass, which raises resting energy expenditure, including during sleep.
Hormonal differences also contribute. Testosterone supports muscle maintenance, while estrogen influences fat distribution and energy regulation. These factors help explain why sleep calorie burn differs between sexes, even when height and weight appear similar.
The relationship between sleep length and calorie burn is straightforward. The longer you sleep, the more calories you burn in total. But the increase is linear and modest.
An extra hour of sleep adds roughly the same number of calories as any other hour of sleep. It does not trigger accelerated fat loss or metabolic changes on its own. While adequate sleep supports overall health, extending sleep far beyond your needs does not meaningfully increase daily calorie expenditure.
Sleep quality has a much greater impact on metabolism than sleep duration alone.
Studies show that poor sleep and sleep deprivation can disrupt appetite hormones, increase caloric intake, and reduce activity, promoting weight gain.
Conversely, obesity worsens sleep disorders like sleep apnea, creating a cycle that heightens cardiometabolic risks.
The environment you sleep in also plays a role, though its effect is limited. Sleeping in a slightly cooler room can raise calorie burn because the body uses energy to maintain its core temperature.
That said, the increase is small and should not be overstated. If the room is too cold or too warm, sleep quality suffers. Uninterrupted sleep matters far more than any minor boost in overnight calorie burn.
Now, let's look at some of the most common myths about burning calories while sleeping.
This is one of the most common misunderstandings. Your body continues to burn calories all night to keep your heart beating, lungs breathing, brain active, and body temperature stable. Sleep lowers energy use, but it never brings it to zero.
Sleeping more does increase total calorie burn, but only slightly. An extra hour of sleep burns roughly the same number of calories as any other resting hour. Weight loss depends on overall energy balance, not just time spent asleep.
Tossing and turning may raise calorie burn by a small amount, but it also disrupts hormones that regulate hunger and metabolism. Poor sleep quality tends to work against weight management rather than help it.
While the difference is not huge, being awake usually burns a little more energy than sleeping because the brain is more active and muscle tone is higher. Sleep still burns calories, just at a slightly lower rate.
There is no reliable way to turn sleep into a fat-burning state. Exercise, muscle mass, and daily movement influence metabolism far more than anything that happens overnight.
A cooler room may raise calorie burn slightly as the body works to stay warm, but the effect is minimal. If the temperature disrupts sleep, the metabolic downside outweighs any small increase in energy use.
You burn calories while sleeping because your body never truly rests. On average, several hundred calories are burned each night simply to keep vital systems running and support recovery. While sleep alone will not drive fat loss, it plays a critical role in metabolic health, appetite regulation, and long-term weight stability. Treat sleep as a non-negotiable part of health, not a calorie-burning trick, and the benefits extend far beyond the numbers.
Disclaimer: What is said in this article has been referenced from multiple sources and is intended only for educational and informational purposes. Please note that no content in this article is a substitute for professional advice from a qualified doctor or healthcare provider. Always consult an experienced doctor with any concerns you may have regarding a health condition or treatment, and never disregard any medical suggestions or delay in seeking treatment because of something you read here.
