Can’t Sleep After a Hard Workout? Here’s What Your Body’s Trying to Tell You

You’d think that the night after a grueling workout would bring some well-earned, much-needed deep sleep. But surprisingly, it’s not uncommon to have difficulty falling or staying asleep the night after a hard session. You might feel like your body is still buzzing, or that as tired as your body feels, you just can’t fully relax.

It turns out, this could be a sign that you're overdoing it or that your workout routine could use some tweaking. Here’s what the experts say about why you can’t sleep post-workout, what it means for your body, and how to adjust your training if challenging workouts are leading to restless nights. 

First things first: Here's how exercise affects your sleep

“Exercise is usually very good for your sleep,” says exercise physiologist and trainer Sharon Gam, PhD, CSCS, ACE-HC. Working out typically improves the time it takes to fall asleep, the number of times you wake up in the middle of the night, and your total time asleep—both in the long-term and on the night that you’ve exercised. 

“Exercise improves the functioning of your nervous system, and more specifically, your parasympathetic nervous system, which regulates sleep,” Gam says. “If that system is working better, usually your sleep is better.”

Gam says exercise has also been found to alleviate symptoms of depression and anxiety, which are both connected to sleep problems, and that it helps manage body composition, which can reduce the risk of sleep disorders like sleep apnea. 

Exercise can also reduce daytime sleepiness, says Kathy Nguyen, MD, a primary care sports medicine physician at Memorial Hermann Medical Group. “That helps regulate our circadian rhythm so that we can have proper sleep at night, rather than feeling tired throughout the day,” she says. 

And as you might expect, “a lot of people report that during higher training volumes, they’re more tired, and they sleep better,” says Laura Norris, a RRCA-certified running coach and certified personal trainer. “You need more sleep when you exercise more.”

Why you might be having trouble sleeping post-workout

But there’s a flip side to the relationship between sleep and exercise, and if you find that your workouts are negatively impacting your ability to fall and stay asleep, it could be for a few reasons. 

“When you exercise, it releases these hormones and neurotransmitters that put you in a stimulated state and activates your sympathetic nervous system, which is your flight-or-flight system,” Gam says. “But to go to sleep, you need the opposite—you need the parasympathetic nervous system to be ramping up. And for most people, that’s what happens.” 

But in some cases, that flight-or-flight response could be sticking around for too long—and messing up your sleep. One reason why: “Someone may have a lot of life stress that’s piling on top of that exercise stress response and not letting the recovery response take over,” Gam says.

That stress response may also stay for too long if someone is a beginner whose nervous system isn’t yet adapted to exercise, Gam says, or if someone has dramatically ramped up their training all at once. Or, it could be that you’re just doing intense exercise too close to bedtime. “It does take some time for your body to shift out of stress mode and into that rest mode,” she says. Intense exercise also increases your core body temperature and heart rate, Dr. Nguyen says, which can take a while to drop and can interfere with sleep if it happens too close to bedtime. 

If trouble sleeping post-exercise is a chronic problem, it could be that you’re overtraining, and/or possibly underfueling, Norris says. “If an athlete is noticing that they chronically find exercise disrupts their sleep, they want to look at if they’re doing too much intensity or too much training load, and they want to look at if they’re underfueling, whether around workouts or throughout the day,” she says. “Not enough carbohydrates will leave your body in more of a stress response, and that will elevate cortisol levels.”

If it’s a one-off time where you can’t sleep, or it’s after a big race, it’s not a concern, Norris says. But when it’s a pattern, you want to examine your training and nutritional habits.

To give your body enough time to ramp down after big workouts, aim to finish them at least three hours before bedtime.

How to fall—and stay—asleep after a hard workout

1. Save intense exercise for earlier in the day

To give your body enough time to ramp down after big workouts, aim to finish them at least three hours before bedtime, Dr. Nguyen suggests. That should allow your cortisol levels, body temperature and heart rate to return to normal. (Easier workout sessions won’t have the same kind of hormonal response, and can be done closer to bedtime, Norris says.)

Another reason to get your tough sessions done long before it’s time to hit the hay? “When you’re doing intense exercise, you may be drinking more water, so you’re running to the restroom more often,” Dr. Nguyen says. “That’s one of the biggest reasons people wake up in the middle of the night.” 

2. Use caffeine wisely

“Some athletes use a lot of caffeine around exercise sessions,” Norris says. “Maybe they realize it or maybe they don’t, but it’s in a lot of sports nutrition products.” Read the labels on your gels, pre-workouts, and drink mixes so you know exactly how much caffeine you’re consuming, and skip it entirely for late-in-the-day workouts.

3. Prioritize your cooldown

“The post-workout cooldown is what essentially puts the brakes on the sympathetic nervous system and the stress response and starts to ramp up that parasympathetic nervous system and recovery response,” Gam says. She recommends spending five minutes post-workout doing deep belly breathing, making sure your exhale is longer than your inhale. “That can slow your heart rate and tell your parasympathetic nervous system to start working.”

4. Focus on fueling

Prioritize fueling around your workouts and throughout the day to avoid the high-cortisol response that can come with being underfueled. A sure sign you could use some more calories in your diet? If you’re waking up in the middle of the night because you’re hungry, Norris says. If that’s the case, she recommends a pre-bed snack. 

5. Keep track of your habits

Gam suggests keeping a log of your sleep and exercise so you can be aware of any patterns that emerge. “Log which workouts you’re doing, how you slept that night, and how you’re feeling,” she says. “Take a look and see: ‘Am I doing a lot of intense workouts and having some issues sleeping? Maybe I need to drop my intensity down.’ Do that for a couple of weeks, see how you respond, and make adjustments from there.” 

6. Be wary of overtraining

If trouble sleeping is coinciding with other symptoms like extreme muscle soreness or stiffness, loss of appetite, fatigue or irritability, it’s possible that you have overtraining syndrome, which is a diagnosable medical condition and typically merits a full break (of several days to several weeks, depending on the severity) from exercise, Gam says. 

“If it’s not quite to that point, but somebody is just finding that they’re having a hard time sleeping, I would still look at their intensity and their volume and take a little step back,” Gam says. “If they’re used to doing a lot of high-intensity training, sprinkle in some more moderate-intensity training or cut their total workout time a little bit to give their body more of a chance to recover.”