Why You're So Tired After a Workout and What to Do About It

If you consistently wonder, "Why am I ‌so‌ tired after working out?" let's take a pause. Exercise should make you feel energized — not exhausted. Sure, you're bound to feel a bit tired after a workout from time to time, but you shouldn't completely crash after a workout.

It's important, though, to differentiate between feeling tired or worn down after exercise and feeling sleepy (aka the need to go back to sleep). While it may seem like splitting hairs, distinguishing between the two sensations can help you hone in on their root cause.

So can working out make you tired? Yes. Sleepy? That, too. Here are some reasons you might feel especially tired or sleepy after a workout and what you can do about it.

There are multiple potential causes of tiredness after a workout. Here are some of the most common ones:

While it may sound obvious, the more intense your fitness routine, the more you'll typically feel tired the day after a workout.

During exercise, the body harnesses energy from a molecule called adenosine triphosphate, or ATP, to keep you moving, according to the University of New Mexico. When your routine is too strenuous, it can leave your energy reserves (ATP) depleted. As a result, you may feel extreme fatigue after a really grueling training session as your body works to recover.

Keeping your body properly nourished helps prevent you from feeling tired during a workout —and after. Your diet has a direct effect on your muscles' ability to recover after a workout and on your energy levels after the fact.

The Mayo Clinic recommends that, each day, you eat a whole food-based balance of carbs, healthy fats and protein. Before you sweat, opt for a fast-digesting carb snack, like bananas or oatmeal. Then, follow your workout with some protein and carbohydrates to support muscle repair and rebuilding.

Regardless of your fitness level or preferred exercise, drinking enough water during and after your workout is important. When you exercise, your body can lose large amounts of fluid through sweat.

As a result, it's easy to become dehydrated if you don't drink water frequently, according to the University of Utah. When your body reaches a state of dehydration, tiredness or lethargy can occur and your muscles can't adequately recover.

In most cases, you can easily improve feelings of fatigue after exercise by modifying your pre- and post-workout routine or altering your fitness regimen. However, this isn't always the case.

Certain medical conditions make it harder to recover from a workout, including diabetes, chronic fatigue syndrome, COPD, multiple sclerosis and sleep apnea, according to the Mayo Clinic. Thyroid or heart may also be to blame. If you have any concerns, it's best to speak to your physician so that you can rule out these conditions.

If your bed is calling after lifting weights (or any other workout), one of these three things may be why you feel sleepy after exercise.

Your body's natural circadian rhythm plays a role in the time of day that's best for you to work out. That internal clock is involved in regulating your internal temperature, blood pressure and heart rate, according to the National Institute of General Medical Sciences.

These, in turn, influence your ability to complete and recover from a workout. Just as a night owl may have a hard time focusing on a work-related task in the early-morning hours, an early bird may feel more easily exhausted after a late-night workout. Listen to your body's natural rhythms to avoid sleepiness after lifting sessions, runs and cycling class.

Sleep and exercise go hand in hand. Regular exercise can improve sleep quality and feelings of sleepiness during the day, according to Johns Hopkins Medicine. In addition, getting enough sleep helps replenish your energy reserves after a workout, according to the National Sleep Foundation.

So it makes sense that a lack of sleep the night before a workout can leave you feeling extremely sleepy after exercising.

Certain diagnoses, like sleep apnea, can lead to feelings of sleepiness, according to the National Sleep Foundation. Exercising with one of these can further exacerbate your fatigue and make you feel as if returning to bed is the only option.

Taking certain supplements or medications can also contribute to the problem. Consult your healthcare provider early on to help you manage your sleepiness and make regular exercise more manageable.

In most cases, a few simple changes to your daily routine can help improve or prevent fatigue and sleepiness after your workout. Try these five tips to feel better after exercise.

Don't blame yourself for getting tired. Instead of forcing yourself to march back into the gym, take the cues your body is giving you.

When you're tired, your body is demanding rest and nutrients to rebuild your muscles and energize you, according to the National Sleep Foundation. Although your workout might have been what pushed you over the edge, chances are you're neglecting your body before you even hit the gym.

It's imperative to eat nutritious foods both before and after you exercise to fuel your body and replace lost calories, vitamins and minerals. Be sure to avoid eating too soon before your exercise routine, however, as this may lead to stomach discomfort.

If you plan on exercising for less than an hour, your pre-workout snack should include a pairing of easily digested protein and a fast-burning carb source, like a yogurt, smoothie, whey protein shake with fresh berries or apple slices and string cheese.

If you're working out for longer than an hour, a bowl of Greek yogurt with a handful of granola can help provide you with the energy to sustain your routine.

After your session, refuel your body with a snack or meal that contains both protein and complex carbohydrates, like oatmeal with fruit and almond butter, banana and cottage cheese, nuts and an apple, hummus and carrots, whole-grain toast with peanut butter or a protein shake. This will replace the glycogen (carb) stores that you've burned during exercise, providing an energy boost.

Staying hydrated is crucial to preventing dehydration as you sweat off fluid while you exercise. This involves drinking plenty of fluids before, during and after your workout.

The American Council on Exercise recommends people drink between 2.7 and 3.7 liters of water a day. Drink 2 to 3 cups of water two hours before exercise. Have a cup five to 10 minutes before your session begins and then 1 cup for every 15 to 20 minutes of exercise, recommends the University of Colorado Hospital.

And on days you're planning extreme exercise (either high-intensity workouts or outdoor workouts in the heat), it's particularly important to make sure you're well-hydrated to optimize your workout and prevent post-exercise fatigue. During intense exercise, drink 7 to 10 ounces of fluid every 10 to 20 minutes.

You can also opt for a sports drink, which contain electrolytes and carbohydrates, but it's not always necessary unless you're working out for more than an hour or under extreme heat.

If you've been burning the candle at both ends, exercise might be impossible. If you're spending your nights studying, working or taking care of your family instead of sleeping, you're depriving your body — and this can make you feel even more tired after a workout.

Get seven to nine hours of sleep a night to allow your muscles to rest and rebuild, recommends the National Sleep Foundation. Getting too little or too much sleep can lead to tiredness after a workout (not to mention throughout the rest of the day).

Try to go to bed at the same time each night and wake at the same time each morning. Additionally, sleep in an environment that's dark, relaxing and not too hot or too cold.

In rare cases, fatigue or exhaustion may be the result of a medical condition. If you have any medical symptoms in addition to your exhaustion after exercising, contact your doctor.