The quality and duration of your sleep are associated with increasing muscle mass and strength.
Sleep is an important part of biological and mental regeneration processes. If you don’t get enough sleep, or better to say, if you don’t get enough restorative sleep you won’t be able to concentrate, socialize with people, have a quality life, and your physical performance will decrease. The tiredness and concentration issues that you can experience after a bad night of sleep can prevent you from your normal level of physical activity and that can lead to a reduction in muscle mass1.
Sleep doesn’t mean your body is completely resting. Actually, sleeping is a time when your brain is actively working to remove unwanted metabolic waste while also enhancing blood flow to the cells. During deep stages of sleep, the blood that flows to your muscles is increased. Blood flow is how we transport oxygen and nutrients that aid in recovery, cognitive performance, and the repair of muscles and cell regeneration to the affected parts of our bodies.
A good night’s sleep allows time for hormones to repair tissue, but how much sleep makes a “good night’s sleep”?. Before jumping into exactly how many hours of sleep to build muscle and quality of an ideal sleep pattern for building muscle, let’s dig into the relation between sleep and muscle growth.
How Sleep Deprivation Affects Muscle Growth ?
Science2 defines sleep loss as a potent catabolic stressor which is characterized by whole-body protein loss, reflecting loss of muscle proteins. This increases the risk of metabolic dysfunction and loss of muscle mass and strength. One full night of low quality sleep is sufficient to provoke an anabolic resistance (reduced stimulation of muscle protein synthesis) and a catabolic environment (losing overall mass, both fat and muscle).
Less sleep could also mean decreased muscle mass as it was shown in a 2011 study3 that found that people who only got 5.5 hours of sleep per night saw a 60% reduction in muscle mass by the end of the study. In contrast, the participants who got 8.5 hours of sleep per night experienced an increase of 40% more muscle mass. All participants ate the same amount of calories per day.
In another study, researchers compared the changes in adipose tissue and skeletal muscle after one night of sleep loss and after one full night of sleep. The results indicate that levels of structural proteins in skeletal muscle decrease in response to sleep loss, in opposition to increased levels of proteins linked to adipogenesis in adipose tissue. So, in just one night of no sleep, muscle protein synthesis, the process of building muscle mass, was reduced; and fat tissue accumulated proteins promoting fat storage.
A large-scale study among 1,196 elderly women found that poor sleep is associated not only with reduced muscle mass but also with decreased grip strength.
Can the Process of Muscle Recovery be damaged by Sleep Deprivation?
Sleep has a huge contribution in the muscle building process and muscle recovery after certain kinds of tissue damage, like intense training sessions or injury. Muscle has the ability of recovering from several types of damage thanks to its plastic properties. For this to happen, different molecular changes occur helping damaged cells to recover or be replaced by new cells. One of these changes is related to protein metabolism.
To understand the process of muscle growth and protein metabolism we need to keep in mind that muscle mass is maintained on the basis of an energy balance. Muscle mass is the result of a balance between the rates of protein synthesis and breakdown. If there is more protein synthesis than breakdown then the muscles will develop (hypertrophy), but if there is more protein breakdown then we have a loss of protein content allowing for a loss in muscle mass (muscle atrophy).
So yes, sleep debt damages muscle strength and impairs the process of muscle recovery because of an increased stimulation of protein breakdown. Skeletal muscle is made up of 80% proteins4 and maintaining optimal muscle protein metabolism is critical for muscle health.
Female Hormonal Inputs and Human Growth Hormone
The maintenance of muscle mass is tightly regulated by hormonal and nutritional factors that also modulate the balance between synthesis and breakdown of protein. Hormonal components like testosterone and IGF‐1 positively regulate muscle mass and protein metabolism by promoting muscle protein synthesis at the same time as repressing protein breakdown.
Previous studies5 have shown that increased levels of IGF-1 are associated with improved sleep quality and that testosterone was reduced by 24% after just one night of sleep deprivation (less than 4 hours of sleep).
IGF-1 is a hormone that manages the effects of growth hormone (GH) in your body. Together, IGF-1 and GH promote the growth of bones and tissues. So, IGF-1 plays an important role in protein synthesis and the maintenance of muscle mass6. During the deep and slow-wave sleep stage called non-REM sleep, the pituitary gland releases growth hormones that stimulate muscle repair and growth as well as assist in raising other hormone levels including the insulin-like growth factor hormone or IGF-1. Not enough sleep causes a sharp decline in growth hormone secretion.
As mentioned before, testosterone is a potent regulator of muscle protein synthesis. Women have 10 times lower7 concentrations of testosterone than typical male levels. This may explain the reason why in sex-specific studies the negative effect of sleep deprivation on testosterone levels appeared to be more significant in male participants. For example, this study found that optimal sleep duration increased grip strength only in male participants. In this study, older men who reported poor sleep (quality and quantity) showed lower muscle mass and grip strength than women in the same range of sleep debt.
In addition to these studies, researchers8 found that biological conditions unique to women, including menstrual cycles and female hormones are related to sleep pattern and sleep duration. Plus, this study9 showed that when women are in their menstrual phase they experience a delayed muscle recovery.
With all this in mind we could say that menstrual cycles and female hormones might play an important role influencing the association between sleep and muscle growth and strength.
But it’s not clear yet if the difference in testosterone levels between women and men could explain the differences in protein metabolism affecting the maintenance or development in muscle mass while sleeping in both sexes.
Prolactin is another hormone present during sleep and it helps regulate inflammation. If you don’t get enough sleep, you’re more likely to experience inflammation in the body which can make recovery more difficult and increase the risk of further muscle injury.
How many hours of sleep to build muscle?
There seems to be an agreement that between 7 to 9 hours of nighttime sleep every night will help maximize muscle growth and keep you healthy. This is a sleep cycle you need to practice every night because when you have trouble sleeping for this long and for several days in a row, your workout performance and progress will be negatively impacted. Muscles and tissues repair and rejuvenate as we sleep.
Tips on how to Improve Adequate Sleep
- Don’t eat right before bed. If your body is trying to digest while also trying to sleep, your sympathetic nervous system (stress response) will be fighting with your parasympathetic nervous system (rest/relax response) which will most likely result in sleeplessness.
- Practice relaxation techniques like deep breathing or meditation. These exercises10 will help you lower the heart rate and blood pressure, slow and deepen your breathing, and create an increased sense of comfort for you to naturally fall asleep.
- Avoid caffeine a minimum of 6 hours before bedtime. Caffeine can impact the onset of sleep and reduce sleep time, efficiency, and satisfaction levels11.
- Limit screen time. Studies12 show two or more hours of screen time in the evening can seriously disrupt your levels of melatonin needed to fall asleep. Consider turning off electronic devices at least one hour before sleep.
- Create a pre-sleep routine like stretching before bed to help your body and muscles relax. Going through the same routine every night can help let your body know that it’s time for bed and help you slow down and relax.
- Create the best sleep environment for you. Cool, comfy, quiet, and dark. Give your body and mind a peaceful and relaxing environment to rest.
Finally, don’t forget that proper and regular sleep also influences the body’s response to stress and nutrition and helps with decision-making. Research shows that men and women deprived of deep sleep were much more likely to make poor nutrition choices. This is good to keep in mind when thinking about your fitness goals and habits and wondering why you might not be making the progress you would like.
Make sure you develop sleep hygiene by sleeping seven to eight hours per night. Nine hours is not bad at all, especially if you are looking to change your body composition, build muscle and increase your strength. More sleep means more time for muscle recovery through protein synthesis and human growth hormone release. Even if it’s recommended up to 10 hours of sleep, the truth is that the amount of sleep our bodies need differs from one to another. So, follow your guts and if you feel you aren’t getting enough sleep taking into consideration the tips we provide here is a good start point.
Have a nice workout, nutritious food, sweet dreams and fast recovery!
Giuliana is a yoga instructor and Crossfitter from Peru who is currently living in Chiang Mai, Thailand with her Crossfit Coach (and husband) Tim.