Lifting heavy weights, eating plenty of protein, following a consistent fitness routine. When you think about how to build muscle, these are the habits that likely come to mind. But equally important for muscle growth, experts say, is getting enough rest.

“Sleep is essential to both muscle growth and recovery,” says Alex Dimitriu, MD, a double board-certified psychiatrist and sleep medicine specialist, and founder of Menlo Park Psychiatry & Sleep Medicine. “During sleep, our bodies restore energy stores, reduce inflammation, and produce growth hormones.” This full-body rehab process is key for everyone, he adds—but particularly for people leading an active lifestyle. 

Here’s why the connection between sleep and muscle growth is so strong, plus how many hours you should aim for every night to promote effective gains. 

The Connection Between Sleep and Muscle Growth

You know that getting enough sleep each night can boost energy, reduce stress, and help you wake up feeling refreshed. And if you’re trying to build muscle, sleep also plays a critical role in supporting your strength gains.

“Muscle growth is dependent upon many factors, but probably key among them is growth hormone, or GH, which is secreted during healthy deep sleep,” says Chris Winter, MD, a neurologist, sleep specialist, and host of the Sleep Unplugged podcast. Sleep gives our bodies time to secrete GH, he explains, so if you’re consistently not getting enough of it or sleeping poorly, you’ll lose out on this important hormone.

In addition to building muscle, getting enough good sleep may also give us an opportunity to improve existing muscle: “Our bodies can repair micro-tears in muscles during sleep,” Dr. Dimitriu says—another important element of the link between sleep and muscle growth. 

Research suggests that both sleep duration and quality can affect muscle mass. In a small study of people older than age 65, for example, participants who were good sleepers (meaning they consistently experienced better-quality sleep) had higher lean mass compared to people who tended to sleep poorly. And a large retrospective cohort study published in 2023 identified a decrease in muscle mass among participants who slept poorly, even if they didn’t lose any hours of shut-eye.

Common signs of poor sleep include struggling to fall asleep, waking up a lot during the night, or feeling tired rather than refreshed in the morning, according to the Centers for Disease Control and Prevention (CDC). Poor sleep can also negatively impact a number of other anabolic factors, Dr. Winter notes, including insulin and testosterone levels.

What Happens to Muscles If You Don’t Get Enough Sleep?

You’re not alone if you suspect you’re not sleeping enough. According to the CDC, about one-third of American adults report clocking less than the recommended seven hours each night. But not getting enough high-quality sleep can both limit your ability to build muscle as well as weaken existing muscle. “Chronic sleep deprivation may actually lead to muscle loss and impaired growth,” says Dr. Dimitriu.

A number of studies have associated shorter sleep with muscle mass loss. And while more research on this topic is needed, even one or two nights of poor-quality sleep might have an impact. In one small 2021 study, for example, researchers subjected healthy young adults to one night of complete sleep deprivation. After that night, participants experienced anabolic resistance, noticing an 18 percent reduction in post-meal muscle protein synthesis rates. That essentially means their bodies weren’t able to turn dietary protein into new muscle as efficiently.

How Much Sleep Do You Need for Muscle Growth?

Most adults need at least seven hours of sleep a night, according to the US Department of Health and Human Services. But this number isn’t one-size-fits-all, Dr. Winter says. “It can be significantly higher for athletes involved in more intense training or endurance sports,” he says. “Also, there are simply some individuals who possess genetic factors that create more sleep need than the average individual.” Long story short: Sleep needs really vary, and while you should generally aim for at least seven hours a night, the right number for you may be a little different.

Hours of rest may be just one part of the sleep and muscle growth equation, though, since research suggests sleep quality is key too. Fortunately, practicing good sleep hygiene can make all the difference in how well you snooze. Here are the sleep-promoting strategies experts suggest doing every night:

Does Napping Make a Difference?

Though research on the relationship between naps and muscle growth is limited, experts say fitting in more sleep wherever you can is likely a good thing. “[Napping] is probably helpful,” Dr. Winter says. “All rest is performance-enhancing.”

In general, though, while a power nap can help minimize sleepiness and boost alertness, it’s not a replacement for the deep, restorative sleep you bank overnight. “Be careful so that power naps do not interfere with nightly sleep, which should remain a priority,” Dr. Dimitriu says.

The Takeaway

The connection between sleep and muscle growth is major. While you rest, your body secretes an important hormone called growth hormone, or GH, that impacts your ability to build muscles. Research has shown that shorter or poorer-quality sleep can impact muscle mass. Plus, sleep gives your body time to restore and repair itself, allowing micro-tears in your muscles to heal, for example.

All to say: Sleep should be an important part of your overall health and fitness routine, even if it occasionally means hitting the snooze button. “Skipping out on sleep for more gym time is a fool’s errand,” Dr. Winter says. “You are trying to carry water in a colander.”