Whether you’re an elite athlete or a fitness enthusiast, prioritizing recovery and rest are an important part of your overall training regimen. While workouts boost endurance and strength, rest and recovery periods allow our bodies to adapt in response to those workouts. 

That’s because during exercise, you’re challenging your muscles to handle more resistance than they normally do. This increased resistance causes microscopic tears within the muscle tissue and increases the rate of muscle protein breakdown, a process known as muscle hypertrophy.

This “damage” activates cells from outside the muscle fibers, which are drawn to the area of the tears. The cells then replicate, mature into grown cells, and fuse to your muscle fibers, forming new muscle protein strands. This is known as muscle protein synthesis, says Jenna Gress Smith, PhD, founder of Arizona Sleep & Health. “Over time the synthesis process outpaces muscle hypertrophy and ultimately increases muscle mass and strength – particularly if you’re getting good sleep.”

How sleep supports muscle recovery

Sleep is generally divided into two phases, REM (rapid eye movement) and NREM (non-rapid eye movement). 

While the REM sleep phase is when your body focuses on reenergizing your mind, the NREM phase, and specifically the deep sleep stage, is when your body’s physically restorative processes take place. With your brain less active, the blood supply to your muscles and tissues increases, delivering oxygen and nutrients that promote muscle repair and growth. Let’s dig into some specific connections between sleep and muscle recovery.

1. During sleep, growth hormones are released

“Sleep is so important for muscle recovery because that’s when the body releases most of its human growth hormone (hGH),” says Michael Breus, PhD, clinical psychologist and Diplomate of the American Board of Sleep Medicine and a Fellow of The American Academy of Sleep Medicine. “During the deepest stage of NREM sleep, the pituitary gland secretes about 70 percent  of the hGH it makes, which stimulates tissue growth and helps repair muscles from both exercise and normal daily wear and tear.” HGH has also been shown to help heal damage to tendons and ligaments by synthesizing collagen.

According to a University of Chicago study, when you are sleep deprived, your body produces less growth hormone, which in itself is associated with a loss of muscle mass and reduced exercise capacity. 

2. Sleep helps increase muscle mass

Unless you’ve studied human kinetics, you’ve probably never heard of  myofibrillar proteins, the building blocks of myofibrils — tube-shaped cells that bind together to form muscle fibers. “The synthesis of myofibrillar proteins is a metabolic process that’s most responsible for changes in muscle mass after any type of resistance training,” says Dr. Gress Smith. 

So how does sleep fit into the picture? One study found that healthy young men who were sleep deprived for five consecutive nights and then exercised had reduced myofibrillar protein synthesis compared to when they got a normal night’s sleep. “That would decrease the body’s ability to restore muscle damage and likely lead to decreased muscle mass over time,” Dr. Gress Smith says. 

Another study showed similar findings, also pointing out that when muscles don’t fully repair they’re more prone to injury. “Whether it’s through protein synthesis or other pathways, it’s clear that restful sleep and muscle growth and recovery are closely linked,” says Dr. Gress Smith.

3. Muscle glycogen is replenished during sleep

Sleep time is when the body replenishes our muscle’s fuel source, glycogen, which gets depleted when we work out.  “Studies show that sleep deprivation can lower your sensitivity to insulin, which can mean inadequate glycogen replacement,” says Dr. Breus. “Getting enough sleep ensures your body adequately replenishes your muscles’ energy source.”

4. Sleep helps keep inflammation in check

Inflammation is the body’s natural immune system response to fight off things that harm it—for instance infections, toxins—or injuries like micro muscle tears after a hard workout. 

Though you may hear a lot about the dangers of chronic inflammation,  the inflammatory response is actually the body’s first step toward healing and building back stronger muscles. 

In addition to growth hormone, while you sleep the body releases another hormone called  prolactin, which has many biological roles including helping to regulate inflammation. Without enough rest, inflammation in the body can go unchecked, which can make muscle or injury recovery more difficult. 

A growing body of evidence shows that getting enough good-quality sleep leads to improved performance, pain sensitivity, and other biological responses that can speed up recovery from muscle injuries. And that your risk of injury goes up when you train hard and don’t get the proper rest.  

Tips to help you get more deep sleep

Eat fiber-rich foods

Studies show that a diet high in fiber is linked to deeper, more restorative sleep. Fill your plate with whole grains, leafy greens, and fresh fruit. Sprinkle nuts and seeds on a salad for an extra fiber boost. 

Avoid alcohol before bed

“When your body is busy processing alcohol, it has trouble getting past light sleep and into deep sleep,” says Dr. Breus. “This is especially problematic because most of your deep sleep occurs during the first half of the night,  the time most disrupted by a nightcap close to bedtime.” 

Read more about the connection between alcohol and sleep.

Listen to a sleep meditation

Meditation can help quiet a busy mind and improve your overall sleep quality, the first step toward getting more physically restorative deep sleep. Try one of Oura’s sleep meditations to get you out of your head and into sleep mode.

Click here for more tips on how to increase deep sleep.

From the Community:

  • Olympic Swimmer Katie Ledecky answers questions about how she uses Oura to support recovery outside of the pool 
  • Oura member Richard shares how he optimizes his routine to train for ultra triathlons