Most people don’t realize it, but sleep and muscle growth go hand in hand. When you think about building muscle mass, the first thing you probably think of is spending hours in the gym. The next thing you probably think about is the diet and nutrition necessary to help recover and build muscle.

Both of these definitely help but most people probably don’t even consider how sleep can affect building muscle.


During your workout your muscles will build up a large number of microscopic tears on the cellular level. These tears must in turn be repair in order to strengthen and grow the muscle tissue bigger. The two main factors in how well your muscles are repaired after training are sleep and nutrition.

When you’re sleeping, your body enters a higher anabolic state. This basically just means that your body uses the time when you’re sleeping to repair and rejuvenate all of the tissue in your body, including muscle tissue.

While you’re sleeping your body will construct larger molecules which are used to repair various parts of the body including your muscular, immune and nervous systems.

So how Much Sleep Do You Need?

During sleep your body will conduct protein metabolism at a much faster rate than when you are awake. Getting enough sleep every night is crucial to ensuring that your muscles are repaired and recover properly. This is especially true when you’re strength training or trying to get those gains.

Getting a good night’s rest is important every night, although it is even more important on the days you train. You should be aiming for anywhere from 7 to 10 hours of sleep every night. If you sleep any longer than that you may be resetting your body’s natural clock and may find it much more difficult to fall asleep on time the following night. Some people will need 8 hours a night to function others may only need 7.

The Effects of Sleep on Muscle Growth

Sleeping will ensure that your body is able to complete the necessary cycles of repair and recovery in order to achieve muscle growth. When you sleep your body creates spikes in larger amounts of human growth hormone, testosterone and melatonin. Both of these play a huge role in the reproduction and regeneration of cells within the body. Put simply, without enough sleep your body won’t be able to properly restore the damage done to your muscles during training.

Synthesizing Muscle Tissue

In order to build muscle mass, also known as hypertrophy, your body must produce proteins faster than it is breaking down proteins in the muscle.

After absorbing nutrients, your body begins to create proteins to repair and build muscle tissue. Sleep is the longest period your body has between meals to synthesize proteins. By the time you wake up in the morning your body will have used up all of the nutrients you have absorbed during the day and protein breakdown will soon exceed protein synthesis.

Using Amino Acids to Inhibit Protein Breakdown

You can prevent protein breakdown in the body by raising levels of amino acids. These levels must be raised to approximately 25-50% above fasting baseline in order to hinder the effects of breaking down proteins.

Drinking whey protein isolate or casein before bed is an excellent way to inhibit the breakdown of proteins while you sleep. Whey proteins will elevate amino acid levels significantly, although this will only last for a limited number of hours. Casein protein would be the best choice just before bed because it has been found to be much longer lasting and can inhibit protein breakdown for up to 6 hours.

Sleep provides a period where your muscles can rest, recover, and get on with the process of building new muscle tissue, uninterrupted.

Sleep and Cortisol Production

Cortisol is a hormone found in the body which essentially offsets testosterone. It will essentially aid in the breakdown of muscle tissue and inhibit muscle growth. Stress, like the stress caused by not getting enough sleep, can increase cortisol levels in the body, not a good thing when you’re trying to build muscle!

Getting enough sleep will help to lower stress levels, and in turn lower cortisol levels.