Calories are often associated with physical activity, but the human body continuously burns energy, even during sleep. The body requires energy for vital functions such as breathing, circulation, cell regeneration, and temperature regulation. Understanding how many calories are burned during sleep can provide insight into overall energy expenditure and help to manage weight effectively. While most people focus on exercise and diet to control their weight, sleep is equally important in overall health and metabolism. This article will discuss how many calories you burn while sleeping and the factors affecting it. 

What is BMR?

Basal metabolic rate (BMR) is the amount of energy the body requires to perform essential functions while at rest. This includes maintaining organ function, cell production, and sustaining body temperature. BMR is responsible for most of total daily energy expenditure (TDEE), with sleeping calories being a component of it.

BMR varies between individuals and is influenced by various factors, including body composition, genetic predisposition, and overall health. A higher BMR means the body naturally burns more calories, even during periods of inactivity, such as sleep. People with a lower BMR tend to store more calories as fat since their energy expenditure is lower.

Factors influencing BMR

Several factors impact an individual’s BMR, including:

• Age: Younger individuals have higher BMR due to increased muscle mass and cellular activity. As people age, muscle mass tends to decrease, slowing metabolism and reducing the number of calories burned at rest.
• Gender: Men generally have higher BMR than women due to greater lean muscle mass. Since muscle tissue burns more calories than fat, men tend to burn more calories even while sleeping.
• Body composition: Muscle burns more calories than fat, meaning individuals with higher muscle mass have a higher BMR. Individuals with lower body fat percentages and more muscle mass will burn more calories, even in a resting state means men have higher RMR than women.
• Genetics: Some people naturally have a higher metabolic rate. Genetic factors play a significant role in determining BMR, impacting how efficiently the body uses and stores energy.
• Hormonal influences: Thyroid hormones play a crucial role in determining metabolic rate. An underactive thyroid (hypothyroidism) slows metabolism, reducing calorie burn, while an overactive thyroid (hyperthyroidism) speeds up metabolism, increasing calorie expenditure.
• Health conditions: Conditions such as hypothyroidism can lower BMR, while hyperthyroidism can increase it. Other factors, such as diabetes and metabolic disorders, can also impact the body’s ability to burn calories efficiently.

How many calories do you burn while sleeping?

Calculating calories burned

On average, an individual burns 50 to 80 calories per hour while sleeping. This number varies based on weight, metabolism, and sleep quality. To estimate the total number of calories burned during sleep, the following formula can be used:

Calories burned per hour = (BMR / 24) x sleep hours

For example, if an individual’s BMR is 1,600 calories per day and they sleep for 8 hours:

(1,600 / 24) × 8 = 533 calories burned during sleep.

A person with a higher BMR, such as an athlete or someone with more muscle mass, may burn significantly more calories during sleep. Additionally, lifestyle choices and overall health impact the efficiency of the body’s energy expenditure.

Impact of weight on calories burned

Body weight significantly influences calorie expenditure during sleep. Heavier individuals generally burn more calories than lighter individuals over the same duration, as their bodies require more energy to sustain essential functions, even at rest. However, the metabolic rate decreases continuously during sleep, reaching its lowest point in the morning. Research indicates that metabolic rate declines faster in individuals with higher body weight, BMI, and fat-free mass (FFM). This means that while heavier individuals burn more calories overall, their metabolic rate drops more rapidly throughout the night.

Sleep stages and caloric expenditure

Sleep is divided into different stages, each influencing the body’s energy usage differently. The metabolic rate varies throughout the night, depending on the depth of sleep and physiological activity.

Light sleep: In the early sleep stages, the body is relaxed, with a slight decrease in metabolism. Caloric expenditure is lower during this phase compared to other sleep stages. The body begins its repair processes, and energy consumption is moderate.

Deep sleep: During deep sleep, body functions slow down, but cell repair and muscle recovery increase. The body burns a moderate amount of calories in this stage as growth hormones are released, stimulating muscle repair and regeneration.

Rapid eye movement (REM) sleep: REM sleep is when brain activity peaks, resembling wakefulness. This stage consumes the most energy, leading to increased caloric burn. Since the brain remains highly active during REM sleep, energy consumption rises, making this stage the most metabolically demanding part of the sleep cycle.

Factors affecting calories burned during sleep

Several factors influence how many calories the body burns while sleeping, including body temperature, muscle mass, and sleep quality.

Body temperature regulation: The body maintains a stable internal temperature during sleep, which requires energy. Sleeping in a cooler room can increase calorie burn as the body expends more energy to generate heat. Additionally, the body may activate brown fat, which helps in burning calories to regulate temperature.

Muscle mass: Individuals with higher muscle mass burn more calories even at rest, including during sleep. Strength training can increase resting energy expenditure by enhancing lean muscle tissue, making it beneficial for weight management.

Sleep quality and duration: Longer sleep durations increase total calories burned. Poor sleep quality can negatively impact metabolism and hormonal balance, reducing overall caloric burn. Sleep deprivation has been linked to weight gain, as it affects hunger hormones such as ghrelin and leptin, leading to increased appetite and decreased energy expenditure.

Can you increase calories burned during sleep?

There are several ways to enhance the number of calories burned during sleep, many of which are related to long-term lifestyle habits.

Exercise and strength training: Regular physical activity, especially strength training, increases muscle mass, which leads to higher calorie expenditure during rest. Building lean muscle mass improves metabolic efficiency, allowing individuals to burn more calories throughout the day and night.

Optimising sleep environment: Sleeping in a low-temperature room forces the body to generate more heat, increasing energy expenditure. Good sleep hygiene can improve sleep quality and optimise calorie burn.

Consuming metabolism-boosting foods: Certain foods, such as protein-rich meals and green tea, can slightly elevate metabolism and increase caloric burn at night. High-protein meals require more energy for digestion, while green tea contains compounds that support fat oxidation.

While sleep is a state of rest, the body continues to burn calories to sustain essential functions. The number of calories burned during sleep varies based on factors such as weight, metabolism, sleep quality, and muscle mass. Understanding this process can help individuals optimise their health and maintain a balanced energy expenditure. By improving sleep quality, increasing muscle mass, and optimising lifestyle choices, individuals can maximise the number of calories burned even while at rest.

If you’re experiencing difficulties with sleep, it’s crucial to seek advice from a healthcare professional. As a sleep and respiratory health specialist, I offer consultations to evaluate and address sleep-related concerns. Don’t hesitate to contact us for professional guidance and assistance.