When it comes to building muscle, people often pay attention to two main things: diet, specifically protein intake, and exercise with emphasis on weight training. However, what most people often forget is that muscle growth is affected by more than just how much protein you eat and how much you can lift.
Sleep is one of those ‘silent’ factors that affect how well and quickly you grow muscle. But how much sleep is enough to build muscle? According to a National Health Interview Survey that was conducted in the United States in 2020, only 28.8% of men and 25.6% of women sleep more than 7 hours a night on average (1).
So, is 6 hours of sleep enough to build muscle? Read on to learn how sleeping to build muscle works and exactly how many hours of sleep you need to get per night in order to build the muscles of your dreams.
For the most part, no it’s not. Despite the above survey showing that most adults don’t sleep more than 7 hours a night, being part of the majority isn’t a good thing in this case. Research and experts recommend that the average adult should get between 7 and 9 hours of sleep a night (2, 3).
Failure to sleep at least 7 hours on a regular basis has been associated with an increased risk of weight gain and obesity, diabetes, hypertension, heart disease and stroke, depression, kidney disease, and death (3, 4).
In addition, getting less than the recommended hours of sleep per night has been shown to impair your immune function, reduce your pain tolerance, impair performance (at work, school, social functions, the gym, etc), and increase concentration issues, the occurrence of mood swings, and the risk of accidents (3, 4).
Sleeping for just 6 hours at night isn’t enough to block muscle growth completely – especially if your diet and exercise routine are on point – but it does make the process harder. As we’ve seen above, getting less than 7 hours of sleep a night can impair your performance and increase the risk of accidents. But how does this affect muscle growth?
This can manifest in multiple ways, including feeling sluggish or weak. When you’re sluggish, this can mean that you’re slower in your workout, which if you’re doing something such as cardio, crossfit, or HIIT exercises can mean that you’re likely unable to complete the workout with high intensity and therefore, not burning as many calories.
Feeling sluggish, especially when working out in a time crunch, can also mean not completing your workout as required. Feeling weak also means that you end up not giving your all to the workout session. Building muscle requires progressive overload, which means the ability to increase the intensity of your workout over time. This can be done by increasing reps, weight, and also just the overall speed/power/intensity of your workout. When you feel weak, you typically cannot do this, which can affect your progress at the gym.
Working out, especially when using weights, requires a certain amount of concentration. This prevents you from dropping weights on yourself or even forgetting your form which can lead to muscle injury, leaving you unable to exercise for a while and slowing down your progress. Trying to get through a workout without enough energy could lead to you rushing to get it finished. This will typically impact your form.
Studies examining the relationship between sleep and muscle growth also continue to show just how much getting less than 7 hours of sleep a night can be detrimental to your gym goals.
One study looking at handgrip strength in over 10,000 Chinese university students aged 16 to 30 years found that better sleep quality led to improved muscle strength in both male and female students.
They also found that in men specifically, those who slept for less than 6 hours a night had less muscle strength than that of those who slept for 7-8 hours and over 8 hours a night (5).
Another study looking at the effect of sleep quality on the health of older adults found that poor sleepers had less lean mass, less hand grip strength, and more fat mass than the good sleepers. The poor sleepers also had higher anxiety and depression levels, and reported a worse quality of life in health-related, mental, and physical domains than the older adults that had better sleep (6).
Another study published in 2023 found that changes in sleep quality and duration affect changes in muscle and fat mass. The scientists found that the worse the sleep duration and sleep quality, the more the fat mass increased in the test subjects. They also found that if sleep quality reduced while sleep duration remained the same, the subjects showed more reduced muscle mass (7). Therefore, it’s important to get enough sleep every night and aim to get better quality sleep.
From these studies, it can clearly be seen that the answer to ‘Is 6 hours of sleep enough to build muscle?’ is a resounding no. 6 hours or less of sleep a night is more likely to lead to skeletal muscle loss and fat gain. With that being said, getting 7 hours or more of sleep a night is not enough to guarantee muscle growth on its own. You also need to work on improving your quality of sleep.
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We’ve seen that a lack of enough sleep can lead to some unfavorable side effects, impaired performance, and an increased risk of injury in the gym. But how does a lack of sleep affect the inner processes in our body, thereby hindering muscle growth? Let’s take a closer look:
You may not be aware of this, but sleep helps you build up muscle through the release of growth hormone during stage three sleep, aka deep sleep or N3 sleep (8, 9). This growth hormone, which is produced in the brain’s pituitary gland, governs our height, bone length, and muscle growth.
When humans are deprived of sleep, their normal sleep cycle is disrupted, which negatively affects growth hormone release. In one study that was published earlier this year (2024) in the Frontiers in Endocrinology journal, researchers stated that sleep disturbances can interrupt deep sleep and the secretion of this growth hormone in both children and adults (10).
Multiple studies on the effects of the growth hormone on muscle show that this hormone has a positive effect on muscle strength, mass, performance, and function, and that a lack or deficiency of this hormone leads to reduced muscle mass and strength (11, 12, 13).
If you have any concerns, please contact a medical professional.
Cortisol is the body’s stress hormone. Total sleep deprivation, disturbed sleep, or even prolonged wakefulness are some of the sleep-related factors that have been shown to increase the production of this hormone in the body (14, 15).
Over the years, studies on the relationship between this hormone and muscle mass and strength in persons of varying age groups have shown that the higher the concentration of cortisol levels in the body, the higher the fat mass. More cortisol in the body also means reduced muscle mass and muscle strength (16, 17, 18).
Testosterone is a reproductive hormone that is found in both men and women, but men tend to have much higher amounts of it than women. In male bodies, this hormone is responsible for the regulation of sex drive (libido), bone mass, fat distribution, and muscle mass and strength, and the production of red blood cells and sperm.
Low testosterone levels in men can lead to muscle wasting, a condition where they lose muscle mass and strength. In a study that was published in 2011, researchers found that just a week of sleep restriction – from 8 hrs and 55 min to 4 hrs and 48 mins – can lead to a decline in testosterone levels in the body (19).
In a review published in 2014, researchers stated that various sleep disorders such as abnormalities of sleep quality, duration, circadian rhythm disruption, and sleep-disordered breathing may result in a reduction in testosterone levels (20).
Seeing how important this hormone is in muscle growth (21, 22) and how failure to sleep enough hours can lead to less production of it, it can be seen that getting less than the recommended hours of sleep is not ideal for growing muscles.
Glucose is a type of sugar that is stored in your body and used as an energy source. It is the only kind of sugar the body can break down for energy supply. Any other kind of sugar we consume is converted into glucose before our muscles can make use of it.
Research on the relationship between sleep and glycogen has shown that during sleep, the body replenishes and accumulates the glycogen levels that are used up during periods of wakefulness. Sleep deprivation interferes with this process and lowers the glycogen availability in the body (23, 24, 25).
Reduced glycogen stores in the body, and particularly in muscles, leads to increased fatigue, which affects gym performance (26).
Read more: Mouth Taping For Sleep & Snoring: Fact Or Fad
No, it’s not. As previously stated, every adult, regardless of their career, is advised to always sleep for 7 to 9 hours a night. A lack of enough sleep has also been shown to affect overall performance. So, for an athlete who is constantly pushing their body to its limits, it would be even more important to ensure that they get over 6 hours of sleep a night.
For example, one study published in the Medicine & Science in Sports & Exercise journal found that when sprint athletes were sleep deprived, the glycogen levels in their muscles were reduced and they had higher perceived stress levels, thereby affecting their performance and making their sprint speed and performance suffer (27).
Another article concluded that sleep loss and associated reductions in muscle glycogen and perceptual stress reduced sprint performance and slowed pacing strategies during an intermittent sprint exercise for male team sport athletes (6).
We can say that you need the recommended 7 to 9 hours of sleep a night in order to gain and grow muscle.
As we’ve seen above, people who sleep this average number of hours have more muscle strength than those who don’t (5). In addition, all the factors listed above show that an ample amount of sleep helps the body function at optimum condition, thereby providing the muscles with all they need to grow bigger and stronger.
We all have different responsibilities and schedules so we can’t say for certain what the best time for you to go to bed for optimum muscle growth is. All we can do is remind you of the recommended number of sleep hours per night. If you know what time you need to wake up, count back 7 hours from this and this will tell when you need to sleep. We recommend getting into bed at least 30 minutes before this time so you can allow your body and mind time to relax and fall asleep more easily. We also recommend limiting your distractions before bed and staying away from blue light that emits from a TV or a cell phone in particular.
As it falls within the recommended 7 to 9 hours, we can say that sleeping for 8 hours a night can help you build muscle.
However, you must remember that sleep isn’t a miracle worker and there are many other factors that contribute to muscle gain or loss. Check out our ‘How long does it take to get in shape?’ article to learn what else can help you achieve your body goals and how long it may realistically take.
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As your body is likely not well rested, we wouldn’t recommend working out vigorously after just 6 hours of sleep. However, if you feel as if you must workout, we recommend doing a short and light workout to avoid the risk of injury. It’s important to listen to your body and always remember that rest is just as important as exercising. It’s unlikely that you’ll be fully rested and mentally refreshed after just 6 hours of rest. Try pushing it to at least 7 hours. As demonstrated above, gaining muscle without an adequate amount of sleep is rather difficult. It may happen, but it will be a slow and frustrating process No, one night of bad sleep won’t undo all your hard work and muscle-growing progress, similar to how missing one workout won’t prevent you from reaching your goals. Just make sure to regain your sleep the next night and don’t make a bad sleeping schedule or skipping workouts a habit. This is the same principle as with eating. Falling off your diet for one day won’t ruin your efforts, but the prolonged eating of junk food or even eating too much healthy food will be your undoing. To learn why you tend to overeat, check out our ’Why do I eat so much?’ article for more information.FAQs
Is it OK to work out with 6 hours of sleep?
Can you be fully rested with 6 hours of sleep?
Can you gain muscle without good sleep?
Does one night of bad sleep affect muscle growth?
No, 6 hours of sleep a night is not nearly enough for muscle growth. Poor sleep hinders your athletic performance and worsens your health in multiple ways. This often-neglected factor turns out to be essential for determining your muscle gains.
If you fall in the category of those who sleep less, try as hard as possible to provide between 7 and 9 hours of sleep for your body. It may take some adjustments to your body and schedule, but we promise that it will be worth it.
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