Whatever your athletic or fitness goals, effort and consistency count. So after a great workout, you may think that the bulk of your effort is done, but getting a great night of sleep is essential to maximize your strengthening routine and muscle recovery.
Before doing a deep dive into the importance of sleep for muscle recovery, and muscle growth, it’s important to understand the two main stages of sleep.
REM (rapid eye movement) sleep is a time of significant brain activity and is believed to be essential to cognitive functions like memory, learning, and creativity. It’s also the stage where your most vivid dreams occur.
Non-REM sleep is the phase of sleep when your body physically repairs itself from the day. NREM sleep is actually made up of 3 stages, with stage 3 being when your deepest sleep occurs. Your brain activity shows a pattern of what are known as delta waves—which is why the deepest stage of NREM sleep is often referred to as delta, or slow-wave, sleep (SWS).
During non REM sleep, your heart rate and breathing slow to their lowest levels, and your muscles relax. With minimal brain activity, the blood supply available to your muscles increases, delivering extra amounts of oxygen and nutrients that aid in their healing and growth. It’s during this time that our body’s physically restorative processes, including muscle repair, take place.
What happens to our muscles when we work out
During a training session you’re challenging your muscles to handle higher levels of resistance or weight than they normally do, which breaks down the muscle tissue, causing microscopic tears—all perfectly normal. This “damage” activates cells from outside the muscle fibers, which rush to the area of the tears, then replicate, mature into grown cells and fuse to your muscle fibers. This process is what forms new muscle protein strands and, over time, increases muscle strength and mass.
How sleep aids muscle recovery
Human growth hormone is released during a good night's sleep
Getting enough sleep is so important for muscle recovery because that’s when the body releases most of its human growth hormone (HGH). During slow wave/non-REM sleep, the pituitary gland secretes about 60 to 75% of the HGH it makes. The HGH goes to work stimulating tissue growth, helping to repair muscle and tissue from the wear and tear that happened throughout the day, or during exercise. (The remaining HGH is released during the daytime.) HGH has also been shown to be a key player in helping to heal damage to tendons and ligaments by synthesizing collagen.
According to a study published in the Journal of the American Medical Association, the more deep sleep you get, the more HGH is released. Conversely, when you skimp on sleep, there’s less growth hormone secretion. According to another study, a deficiency of HGH is linked to loss of muscle mass and reduced exercise capacity. It’s worth noting that both HGH and slow wave sleep naturally decrease as we age.
Muscle glycogen is replenished when you get your eight hours
When we get quality sleep, our bodies also replenish muscle glycogen, a critical energy source that gets depleted when we work out.
Sleep regulates myofibrillar protein synthesis
Myofibrillar proteins are the building blocks of myofribrils—tube-shaped cells that chain together to form muscle fibers. So what does this have to do with sleep?
As with most things, sleep is the great regulator! New research has begun exploring the importance of sleep and how a lack of sleep may lead to loss of muscle mass and decrease muscle recovery.
One study found that a group of men who were sleep deprived and then exercised had less myofibrillar protein synthesis, which would likely result in decreased muscle mass over time. Another study found a broader relationship with sleep duration and muscle mass. That study compared two groups of people that either slept 5.5 or 8.5 hours while reducing their caloric intake. The shorter-sleep group lost more muscle mass than fat. Whether it is through myofibrillar protein synthesis or other pathways, it’s clear that sleep and muscle growth and recovery are closely linked.
Sleep inhibits inflammation
The last pathway that highlights how sleep encourages muscle recovery is through inflammation cells called cytokines. Studies have shown that exercise followed by sleep deprivation was associated with an increase in a particular type of cytokines, which can contribute to chronic inflammation and hinder muscle recovery if the sleep deprivation continues long-term.
Research confirms that regular and adequate sleep helps repair and restore muscles, increases muscle strength and mass, and improves athletic performance. With so many benefits, sleep should be an integral part of every athlete’s and exercise enthusiast’s workout regimen.
How to get more deep sleep...where the recovery happens
Generally speaking, anything you can do to improve your sleep health will also help you get more deep sleep. Here’s a good place to start:
- Aim for 7 to 9 hours of sleep each night, the guideline for healthy adults. The most important thing you can do to increase your amount of deep sleep is to allow yourself adequate total sleep time. Less sleep = less deep sleep.
- Set a consistent sleep schedule, which means going to bed and waking up at similar times each day. Your body runs more efficiently when it’s on a predictable schedule, and this is particularly true with sleep.
- Stay hydrated during the day. Most of us think about hydration in the context of exercise or diet, but research is now exploring the connection between hydration and sleep. Dehydration may create barriers to sleep, and sleep deprivation may also contribute to dehydration — so drink up for good health … and good sleep!