Sleep has a significant impact on muscle recovery. Surely your personal trainer has informed you about the importance of sleep and that if you don’t get enough of it, you’re not going to feel rested in the morning, and your muscles will not recover properly. Aside from being groggy the next day, another pitfall of not getting enough quality sleep is that it affects your efforts in the gym. While you may be able to ‘function just fine’, on a few hours of sleep, doing so still short changes your body composition goals.
Let’s first understand the two main stages of sleep in order to understand sleep’s impact on muscle recovery.
REM (rapid eye movement) Sleep: occurs in cycles of about 90-120 minutes throughout the night, and it accounts for up to 20-25% of total sleep time in adult humans. REM sleep dominates the latter half of the sleep period, especially the hours before waking. REM sleep provides the energy to the brain that supports it during waking hours and is necessary for restoring the mind.
Non-REM Sleep: known as slow-wave or deep sleep, this phase is essential for muscle recovery and restoring the body. Accounting for 40% of total sleep time, during this phase your blood pressure drops and your breathing becomes deeper and slower. Your brain is resting with very little activity, so the blood supply available to your muscles increases, delivering extra amounts of oxygen and nutrients which facilitate their healing and growth. Muscles and tissues are rejuvenated during this phase of sleep.
So, now that we know that the ‘non-REM sleep cycle’ is the most important for muscle recovery, something else which occurs during adequate time in this phase is the secretion of Growth Hormone. As your body enters into the non-REM deep sleep stage, your pituitary gland releases a shot of growth hormone that stimulates tissue growth and muscle repair. Not enough sleep causes a sharp decline in growth hormone secretion. Growth hormone deficiency is associated with loss of muscle mass and reduced exercise capacity.
Sleeping for 7-9 hours per night is crucial, especially if you are looking to change body composition, increase muscle mass and/or if you want to be ready for your personal training session the next day. Sleep enhances muscle recovery through protein synthesis and human growth hormone release. If you want to grow or lean out, stop procrastinating and get to sleep!