Why 8 Hours of Sleep Makes the Same Workout Work Better

You can have a great program, hit your protein and never miss a workout, and still feel like you are spinning your wheels. If that sounds familiar, take a hard look at your sleep.

Training is the signal that tells your body to change. Recovery is when the change actually happens, and sleep is the biggest piece of recovery. Here is what the research shows.

Why 8 Hours and Not 7?

The American Academy of Sleep Medicine and Sleep Research Society recommend at least 7 hours of sleep per night for adults (Watson and colleagues, 2015). So why aim for 8?

Because time in bed is not the same as time asleep. Most people spend some of the night falling asleep, waking briefly or lying awake. If you give yourself exactly 7 hours in bed, you are probably sleeping less than 7. Aiming for about 8 hours in bed gives you a realistic shot at actually sleeping 7 or more.

People who train hard may also benefit from the higher end, since their bodies have more to recover from.

Sleep and Muscle

In a 2021 study (Lamon and colleagues), healthy young adults spent one night without sleep and one night sleeping normally. After the sleepless night:

• Muscle protein synthesis, the process your body uses to build and repair muscle, dropped by 18 percent.
• Cortisol, a stress hormone that tends to break tissue down, rose by 21 percent.
• Testosterone dropped by 24 percent.

That was just one night. Many people live in a steady state of a little too little sleep, night after night.

Sleep and Fat Loss

This one surprises people. In a 2010 study (Nedeltcheva and colleagues), overweight adults followed the same reduced-calorie diet twice for two weeks. Once with 8.5 hours in bed per night, and once with 5.5 hours.

They lost a similar amount of weight both times, but what they lost was very different:

• With more sleep, they lost about 1.4 kg (around 3 pounds) of fat.
• With less sleep, they lost only about 0.6 kg (around 1.3 pounds) of fat, and lost more muscle and other lean mass instead.
• They also reported feeling hungrier when sleep was cut short.

Same diet, same calories, but short sleep shifted the weight loss away from fat and toward muscle. That is the opposite of what most people want.

Sleep and Performance

A study of Stanford basketball players (Mah and colleagues, 2011) asked players to aim for at least 10 hours in bed each night for five to seven weeks. They ended up sleeping almost two extra hours per night on average. The results:

• Faster sprint times
• Free throw and three-point shooting accuracy each improved by about 9 percent
• Faster reaction times, better mood and less fatigue

You may not be a college athlete, but the principle is the same. Better sleep means better workouts, and better workouts add up to better results.

Sleep and Injury Risk

A study of adolescent athletes (Milewski and colleagues, 2014) found that those who slept less than 8 hours per night were about 1.7 times more likely to get injured than those who slept 8 or more. Tired bodies and tired brains make more mistakes, and that includes in the gym.

How to Get Closer to 8 Hours

You do not need expensive gadgets. Start with these:

• Work backward from your wake time. If you get up at 5:30 am, an 8-hour sleep window means being in bed by 9:30 pm.
• Keep the same schedule every day, including weekends, as much as you can.
• Make your bedroom cool, dark and quiet. Blackout curtains, a fan and a cooler thermostat setting help.
• Cut caffeine by early afternoon. In one study (Drake and colleagues, 2013), caffeine taken even six hours before bed reduced total sleep by more than an hour.
• Put screens away 30 to 60 minutes before bed and give yourself a short wind-down routine.
• Be careful with alcohol close to bedtime. It can help you fall asleep but tends to make sleep lighter and more broken later in the night.

If you consistently snore loudly, wake up gasping, or feel exhausted no matter how long you sleep, talk to your doctor. Sleep problems like sleep apnea are common and treatable.

What to Do After a Bad Night

One bad night will not erase your progress. If you slept poorly:

• Still go to the gym if you can, but keep it lighter. Drop a set or two or lower the weight slightly.
• Skip trying to set personal records.
• Get to bed a little earlier that night instead of trying to catch up with a long nap.

The Bottom Line

Sleep is the cheapest recovery tool you have. More of it helps you hold onto muscle, lose more fat instead of muscle when dieting, perform better and stay healthier. Aim for about 8 hours in bed so you actually get 7 or more hours of sleep. Protect it like you protect your workouts, and those workouts will finally get the chance to pay off.

Sources

• Watson NF, et al. (2015). Recommended amount of sleep for a healthy adult: a joint consensus statement of the American Academy of Sleep Medicine and Sleep Research Society. Sleep. DOI
• Lamon S, et al. (2021). The effect of acute sleep deprivation on skeletal muscle protein synthesis and the hormonal environment. Physiological Reports. DOI
• Nedeltcheva AV, et al. (2010). Insufficient sleep undermines dietary efforts to reduce adiposity. Annals of Internal Medicine. DOI
• Mah CD, et al. (2011). The effects of sleep extension on the athletic performance of collegiate basketball players. Sleep. DOI
• Milewski MD, et al. (2014). Chronic lack of sleep is associated with increased sports injuries in adolescent athletes. Journal of Pediatric Orthopaedics. DOI
• Drake C, et al. (2013). Caffeine effects on sleep taken 0, 3, or 6 hours before going to bed. Journal of Clinical Sleep Medicine. DOI