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sleep and muscle growth

The Best Way to Build Muscle? Sleep

What is the link between sleep and muscle growth? If you think rest is for the weak, think again. 

In our busy lives, it’s easy to deprioritize a whole night’s sleep and think that getting by on just a few hours is something to aspire to. However, no matter how many supplements you take, how much protein you eat, and what weights you lift, you won’t see the total result of your efforts without sleep. 

Here’s why having a good night of rest and recovery every night will enhance your health, mood, and fitness. 

How important is sleep for muscle growth?

The short answer: it’s crucial. Here’s why. 

Any form of strength training causes muscular hypertrophy – an increase in muscle mass. This change is caused by microscopic tears within the muscle tissue and an increased muscle protein breakdown rate. 

Cells outside these muscle fibers are alerted to fix this ‘damage.’ They then replicate, become grown cells, and fuse with these muscle fibers, creating new protein strands. And when does most of this ‘healing’ take place? While you sleep. 

During sleep is also when your body replenishes glycogen, the fuel source for your muscles. When you work out, it naturally becomes depleted. So, if you plan on exercising again (which you probably do), you must get sufficient rest to recover and replenish your energy sources.

Does lack of sleep affect muscle growth?

If you’re working out loads but not prioritizing your sleep, you may be working harder, not smarter. Some research suggests you could be undoing all of your good work by not resting adequately each night.

2011 study from Brazil followed the sleep schedule of two groups of people over 72 hours. One group was only allowed 5.5 hours of sleep per day, while the other was allowed 8.5 hours. The difference? The first group had 60% less muscle mass after three days, while the second group had 40% more. This study suggests that a lack of sleep can lead to a catabolic environment where your body begins to break down muscle mass.

A more recent study from Australia went further by depriving a group of healthy young men of sleep for five nights and then having them complete some exercise. They found that “sleep restriction can have detrimental effects on the processes that maintain muscle mass… (which) may partly help to explain previous reports of reduced muscle mass in those experiencing insufficient sleep.”

How much sleep do you need for muscle growth?

The average adult needs around 7-9 hours of sleep each night. Regularly having this much sleep is especially important for those looking to increase their muscle mass or change their body composition. Having a good night’s sleep before and after every workout will ensure you reap the benefits of all your effort.

Is six hours of sleep enough to build muscle? Not really. If you struggle to achieve a solid seven hours of rest every night regularly, then it’s probably time to prioritize your sleep. Try some of the recommendations below on how to get more sleep.


Ensuring you have adequate sleep every night will always be good for your mind and body. So, it’s always best to aim to be well-rested rather than focus on a particular type of sleep.

However, it is helpful to know more about why and how you sleep, especially with regard to muscle growth. Every night, your rest and recovery comprise different sleep stages. Each stage brings various benefits, from memory and emotional regulation to building bones. 

During N3, the deepest stage of NREM (non-rapid eye movement) sleep, your body completes its most physically restorative processes. Your brain slows in activity, your blood pressure drops, and your breath becomes deeper and slower. Your muscles and tissues are rejuvenated by an increased supply of blood, which provides more oxygen and nutrients for repair and growth. 

How can you measure your sleep for muscle repair?

Polar’s Sleep Plus Stages™ can tell you exactly how you slept the previous night every morning. Tracking both the quantity and quality of your sleep can provide insights into how long you slept and how long you spent in light, deep, or REM sleep.

After any strength training or workouts focused on your muscles, pay attention to what percentage of deep sleep you had that night. You can help to maximize your sleep after every workout by checking out some of the following ideas.


There are many ways we can enhance our capacity for sleep. However, the golden rule is to keep a regular sleep schedule. By going to bed at the same time every day, you teach your body when it should be asleep and when it should wake up.

Still regularly struggling to have a deep, restorative night of rest? Here are some more ways you can adjust your habits throughout the day and night to help maximize your sleep and muscle growth.

  • Eat fiber-rich foodsstudies have shown that whole grains, leafy greens, and fresh fruit are linked to deeper sleep.
  • Avoid alcohol and caffeine in the afternoon and evening.
  • Avoid intense exercise before bed: make sure you have completed any workouts at least three hours before your regular sleep time.
  • Turn off overhead lights two hours before bed. Switch on lamps instead to help your body prepare for sleep.
  • Reduce any exposure to blue light in the evening. Switch your devices to Night Mode.
  • Create the right sleep environment.
  • Try a sleep meditation.
  • Buy a new mattressstudies have shown that people with a newer mattress sleep better, have higher energy levels, and are more likely to be physically active.

If you liked this post, don’t forget to share so that others can find it, too.

Please note that the information provided in the Polar Blog articles cannot replace individual advice from health professionals. Please consult your physician before starting a new fitness program.

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