How Many Calories Do You Burn While Sleeping

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People burn calories all the time. This includes sleep, which plenty of people overlook. Have you ever wondered how many calories you burn while sleeping?

It’s actually quite a commonly asked question with, thankfully, a good body of evidence to draw on as we look for an answer.

The body doesn’t stop working when you’re asleep. Far from it, in fact – it’s when it gets a lot of housekeeping done, so to speak. This means that your Basal Metabolic Rate (BMR) continues to tick along; you will still be burning calories.

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Your BMR is the amount of energy your body needs to perform essential functions while at rest. This includes things like breathing, circulating blood, and regulating body temperature – passive things or things that you don’t do actively. And your body needs calories for all of these things. 

Understanding how calorie burn works during sleep is not only valuable for those looking to boost their own personal health but also for personal trainers who want to educate their clients on every aspect of weight loss, metabolism, and overall wellness – and to get the best results for their clients as a result.

Factors Influencing Calorie Burn During Sleep

There are several factors at play that will influence and collectively decide how many calories your body will need during sleep. These variables are important – you will need to understand them as you work to optimise your own or a client’s health and fitness strategy.

These factors include:

• Age: Our metabolisms naturally slow down as we age. Older people may burn fewer calories overall and fewer during sleep, as their bodies simply need less energy to perform basic functions.
• Body Composition: Body composition plays a significant role in calorie burn. Muscle mass uses more energy than fat, meaning that those with more muscle mass will typically burn more calories. Age-related atrophy (sarcopenia) actually plays a large part in slowing down metabolisms as we age. 
• Weight: Heavier people tend to burn more calories during sleep. This is because larger bodies require more energy to perform bodily functions, meaning more calories are burned even while resting. This applies to those with more muscle (see above) as well as excess fat.
• Sleep Quality: Sleep quality greatly impacts your calorie burn. Deep sleep stages, such as REM (Rapid Eye Movement) sleep, will typically see increased energy expenditure over lighter sleep stages. The more restful your sleep – the more deep sleep you get – the greater your energy burn.

Figuring Out Your Calorie Burn During Sleep

You will need to know your BMR to figure out your general calorie burn. The Mifflin-St Jeor Equation is a pretty popular formula for working this out (though, of course, the estimates you get from these kinds of formulae will only ever be that, estimates.) All results are expressed as kilocalories.

The Mifflin-St Jeor Equation takes into account your age, gender, height, and weight:

For Men:

BMR = (10 × weight in kg) + (6.25 × height in cm) – (5 × age in years) + 5

For Women:

BMR = (10 × weight in kg) + (6.25 × height in cm) – (5 × age in years) – 161

So, for instance, if you’re a twenty-five-year-old man weighing 85kg measuring 1.8m, your BMR would be about 1,855 kilocalories.

Armed with your BMR, you can move on to the next step, working out your burn during sleep:

1. Divide your BMR by 24 to get your hourly rate.
2. Multiply your hourly rate by 0.85 to account for your lower metabolic rate while sleeping.
3. Multiply your hourly rate by the number of hours you slept.

Keeping with the above example, at 1855 calories, if you then sleep for 8 hours each night, you may burn around 525 calories during the night.

However, as above, these are only estimates. Those who exercise regularly or have more muscle mass may burn more calories during sleep – their bodies will need extra energy for recovery, repair, and muscle maintenance.

You can also boost your sleeping energy expenditure by improving sleep quality – the more restful your sleep, the more efficient your body will be at burning calories – and by eating a balanced diet, including staying hydrated. A balanced diet, rich in whole foods, will ensure your body has the nutrients it needs to function properly, both during the day and while sleeping, whilst drinking plenty of water and taking in electrolytes will support your body’s metabolic processes.