6 Major Ways Poor Sleep Can Hurt Your Workout

Lack of sleep could slow your reaction times, impede your performance, increase your risk of injuries and lead you to cut your workout short — but that doesn’t necessarily mean you should skip the gym after a night of tossing and turning.

Sleeplessness is associated with a host of health issues from heart disease and depression to weight gain. A slew of studies shows a lack of sleep could also lead to these six surprising impacts on your workout:

Too little rest might make it harder to follow along in a group fitness class or increase the odds of tripping on the treadmill. The Journal of Sports Sciences found sleeplessness impaired coordination, which could cause you to lose a match or sustain injuries.

“You make three times as many mental errors when you sleep poorly,” says Dr. W. Christopher Winter, president of Charlottesville Neurology and Sleep Medicine and author of “The Sleep Solution.”

A lack of sleep can slow you down.

“Your reaction time slows by 1/3 with sleep loss of more than two hours,” says sleep specialist Michael J. Breus, PhD, founder of TheSleepDoctor.com.

One small study showed the reaction times among student-athletes who missed one night of sleep increased 37 milliseconds, which might not seem like much until you’re too slow to block a blow in a kickboxing class.

The combination of slower reaction times and lack of coordination also contributes to an increased risk of injuries.

“When you get more sleep, you decrease your risk of injuries and, if you are injured, you bounce back much quicker [when you are not sleep deprived],” Winter says.

Athletes who slept less than eight hours per night were more apt to experience musculoskeletal injuries, according to 2019 research in the Orthopaedic Journal of Sports Medicine while logging at least eight hours between the sheets decreased the risk of injuries up to 60%.

Fatigue could quash your ability to achieve a new PR. In research published in the journal Medicine & Science in Sports & Exercise, endurance cyclists experienced a 3% decline in performance (increasing their race times from 58.8 minutes to 60.4 minutes) after sleep restriction. In contrast, extending their sleep time by 60–90 minutes per night was associated with a 3% improvement in performance, shaving their race times to 56.8 minutes.

Your immune system depends on the right quantity of high-quality sleep to function properly; spend too little time in dreamland and it’ll hamper your ability to heal. Research showed skin wounds (like blisters) healed up to one day faster among those who got adequate sleep compared to those who were sleep-deprived. Whether you have a blister or a nasty cold, sleep could help you return to your workout routine sooner.

Even if you manage to make it to the gym after a night of tossing and turning, you might call it quits sooner than usual. In one study, regular exercisers were more apt to cut a workout short after a poor night of sleep; those who slept the least logged the shortest times in the gym. The reason? Lack of sleep increases the “rate of perceived exertion” and the harder a workout feels, the more likely you are to clock out early.

“Your ability to deal with pain and push through the hard parts of a workout decreases when you’re not well-rested,” Winter says.

A nap could help. Researchers found a 45-minute afternoon nap improved performance and reduced rates of perceived exertion. In other words, a nap made workouts feel less difficult — and even shorter naps had an impact.

After a restless night of sleep you might want to opt for a shorter workout — 20-minutes on the treadmill instead of a 90-minute circuit — instead of skipping the gym altogether. A brief sweat session could actually help you sleep better.

“You don’t have to be a perfect sleeper, but if you feel like you got less than six hours of quality sleep, get a little more,” Breus says.