As a very approximate number, we burn around 50 calories an hour while we sleep. However, every person burns a different amount of calories during sleep, depending on their personal basal metabolic rate (BMR).

The basal metabolic rate refers to the energy needed for essential functions such as breathing, circulation, temperature regulation, and cellular growth and repair. In most people, the basal metabolic rate accounts for approximately 80% of the total calories burned in a day. The brain itself burns glucose for energy, accounting for about 20% of the calories we consume while at rest.

Sleep is a time for the body to repair and regenerate. In order to do this more effectively, our body temperature drops, our breathing slows, and our metabolism lowers. On average most people burn about 15% fewer calories while sleeping, compared with their basal metabolic rate during the day.

What Factors Affect the Basal Metabolic Rate?

The basal metabolic rate varies from person to person depending on a number of factors, only some of which can be changed:

• Height and Weight: The larger a person’s body, the more calories it requires to function.
• Fitness: Muscle burns more calories than fat, so people who are fit and regularly active burn more calories, even while at rest.
• Gender: Men generally have a higher BMR than women because they tend to have a higher proportion of repair and regenerate.
• Age: Growing children have a higher metabolism, but metabolic needs decrease as we age.
• Diet: Sticking to a healthy diet can help manage body fat composition.
• Sleep Quality: Poor sleep quality and insufficient sleep have a detrimental effect on metabolism.
• Race: Some studies show that African-Americans may have a naturally lower BMR.
• Genetics. Genetics may influence metabolism to some extent.
• Hormones and Medical Conditions: Pregnancy, lactation, menopause, hypothyroidism or hyperthyroidism, and other conditions can raise or lower the basal metabolic rate. Consult your doctor if you believe an underlying condition could be affecting your metabolism.

HEALY WATCH: THE GIFT OF SLEEP