The body continues to burn calories during sleep to maintain life and essential bodily functions. A person can use a specific formula to calculate how many calories he burns at night. Even when you rest and sleep, the body needs a constant source of energy to maintain a wide range of metabolic processes.
Many different factors influence metabolism, which can make it difficult to accurately calculate how many calories a person burns while sleeping. However, by estimating a person’s basal metabolic rate (BMR), it is possible to arrive at a ballpark figure.
In this article, we discuss what BMR is, how to calculate it, and how to use the result to estimate the number of calories a person burns while sleeping. We also offer some tips on sleep hygiene.
What is the basal metabolic rate?
It is essential that the body uses energy continuously for maintenance and for it to function properly. Although the body burns some of its calories through physical activity, basal metabolism accounts for about 80% of all energy expenditure. Basal metabolism refers to all the processes that keep the body alive, functioning, and healthy. These include:
- Blood circulation.
- Cell growth and repair.
- Brain and nervous function.
- Temperature control.
These metabolic processes require a constant supply of energy, so the body is always burning calories, even when a person is resting or sleeping. BMR is the amount of calories the body burns every 24 hours due to basal metabolism. Essentially, it is the number of calories a person would use in a day if they simply rested and were not physically active. There are many different factors that affect BMR, such as age, body size, gender, and genetics. For this reason, everyone’s BMR is different.
Calculation of TMB
To determine how many calories the body burns during sleep, it is first necessary to calculate BMR. This calculation is not easy because many factors influence the BMR.
Accurate measurement of BMR requires the use of special equipment to determine the amount of oxygen a person breathes in and out during a specific period. However, it is possible to estimate BMR using the Harris-Benedict equation, which takes into account a person’s sex, height, weight, and age. For women, the formula is:
- BMR = 665.1 + (4.34 x weight in pounds) + (4.7 x height in inches) – (4.68 x age in years)
For men, the formula is:
- BMR = 66.47 + (6.24 x weight in pounds) + (12.71 x height in inches) – (6.78 x age in years)
These formulas will give the amount of calories that the body will burn for an entire day due to its BMR alone. For example, a 40-year-old man who weighs 195 pounds and is 5 feet 9 inches tall would have an approximate BMR of 1,889 calories per day:
- TMB = 66.47 + (6.24 x 195) + (12.71 x 69) – (6.78 x 40)
- TMB = 66.47 + 1,216.8 + 877.0 – 271.2
- BMR = 1,889.07 calories per day
A 50-year-old woman who weighs 160 pounds and is 5 feet 4 tall would have an approximate BMR of 1,426 calories per day:
- TMB = 665.1 + (4.34 x 160) + (4.7 x 64) – (4.68 x 50)
- TMB = 665.1 + 694.4 + 300.8 – 234
- BMR = 1,426.3 calories per day
Calculating calories burned while you sleep
The body continues to burn calories throughout the night to support its metabolic processes. However, because the body is physically inactive, the metabolic rate is approximately 15% lower when a person is asleep than when awake.
To estimate how many calories the body burns during sleep, a person needs to calculate their BMR per hour and multiply it by the number of hours they sleep before reducing the figure by 15%.
They can do it using the following formula:
- Calories burned while sleeping = (BMR / 24) x number of hours slept x 0.85
The 40-year-old man who weighs 195 pounds and is 5 feet 9 inches tall will burn approximately 535 calories during an 8-hour sleep:
- Calories burned asleep = (1889.07 / 24) x 8 x 0.85
- Calories burned while sleeping = 78.71 x 8 x 0.85
- Calories burned while sleeping = 629.68 x 0.85
- Calories burned while sleeping = 535.23 calories
The 50-year-old woman who weighs 160 pounds and is 5 feet 4 inches tall will burn approximately 404 calories during an 8 hour sleep.
- Calories burned asleep = (1426.3 / 24) x 8 x 0.85
- Calories burned asleep = 59.43 x 8 x 0.85
- Calories burned while sleeping = 475.43 x 0.85
- Calories burned while sleeping = 404.12 calories
It is important to remember that these calculations provide only a rough estimate of BMR and calories burned while sleeping.
Factors that affect BMR
A number of factors can influence a person’s BMR. These include:
- Ethnicity and race.
- Height and weight.
- Hormonal levels.
- Muscle-fat ratio.
- Levels of physical activity.
- Quantity and quality of sleep.
- Pregnancy and breastfeeding.
- General health.
- Health conditions that affect metabolism, such as hypothyroidism and
Sleep hygiene tips
Getting enough sleep is vital to a person’s physical and mental health. Both the quantity of sleep and its quality are important. Not getting enough sleep can affect a person’s energy levels, mood, concentration, and job performance. According to the National Institute of Neurological Disorders and Stroke, research shows that inadequate sleep can also increase a number of people’s risk of health conditions, including:
- Heart disease.
- High blood pressure
The Academy of Sleep Medicine and the Sleep Research Society recommend that people between the ages of 18 and 60 get at least 7 hours of sleep every night. Some tips that can help improve a person’s quality of sleep include:
- Avoid caffeine or other stimulants in the hours before bedtime.
- Sleep and wake up at the same time every day.
- Get regular exercise.
- Ensure that the bedroom environment is dark, comfortable, and cool.
- Wake up to natural light.
- Do something to relax before bed, like read a book or take a hot bath.