Why Does Workout Make Me Sleepy?

It’s a common question, and one that has a variety of answers. In this blog post, we’ll explore some of the possible reasons behind why a workout might make you feel sleepy.


Exercise-induced fatigue is a common phenomenon, and research has shown that regular physical activity is one of the best methods of counteracting fatigue. When engaging in workout, it’s normal to feel tired afterward. But why does this seemingly counterintuitive experience occur? This article seeks to answer that question by providing an overview of known causes of exhausted feeling after working out.

Physiological factors are responsible for exhaustion after exercise, and these effects are both immediate and delayed. During physical activity, biochemical reactions take place in the body that result in fatigue-causing effects primarily from lactic acid and energy depletion. As lactic acid accumulates in the muscle tissue during intense exercise, it contributes to an increase in fatigue as well as aches and pains throughout the body. As you deplete your energy stores, you can become fatigued more easily and quickly because your body is running low on fuel for any foreseeable future activity.

Dehydration can also contribute to the post-workout sleepiness. When exercising vigorously, our bodies use up a tremendous amount of water through sweat to cool us off while maintaining regulated temperatures within our muscle tissues. Replenishing this water helps boost energy levels and alleviates feelings of sluggishness as dehydration impacts mental performance which will further add to feelings or exhaustion after exercise has concluded.

Causes of Exercise-induced Sleepiness

After an intense workout, it can be normal to feel tired and sleepy. Often, the fatigue after a workout is caused by the release of hormones like endorphins and adrenaline. These hormones can make you feel both energized and relaxed at the same time and ultimately make you sleepy. There can also be other causes of exercise-induced sleepiness, such as dehydration or low blood sugar, so let’s look into the details.

Low Blood Sugar

Low blood sugar, also referred to as hypoglycemia, is one of the most common causes of exercise-induced sleepiness. During physical activity, your body is using up its energy stores more quickly than usual. The rise and fall in blood glucose levels during and after exercise can leave you feeling tired or sleepy.

Consuming adequate amounts of carbohydrates before and after workouts can help to keep your energy levels consistent during an exercise session and ward off post-workout fatigue. Eating a snack that combines both protein and carbohydrates within 15 minutes after exercise has been suggested as able to provide an ideal balance for sustained energy levels.

In addition to staving off fatigue, eating snacks rich in complex carbs such as whole grain bread, fruits like bananas and apples, or a mix of oats with some nuts or peanut butter prior to workout can supply your body with the necessary fuel throughout the workout session and leave you powered up for whatever your day has in store!

Release of Endorphins

The effects of exercise on sleep are complex and the research literature is inconclusive. One possible explanation for the phenomenon of feeling sleepy after a workout is the release of endorphins. Endorphins are chemicals that are produced naturally in the body in response to pain, stress, and activities such as running, weight lifting and aerobic exercise. They help to reduce our perception of pain and sensations of stress, but they can also act as sedatives. A surge in endorphin production after exercise may make us feel relaxed, calm, or drowsy. Additionally, endorphins can affect our perception of time and can create a “runner’s high” feeling that lasts long after the activity is complete. As a result, we may become sleepy soon after stopping physical activity due to these chemicals having a calming effect on our body and mind.


One of the main causes of exercise-induced sleepiness is dehydration. When your body does not have enough water and electrolytes, it can become dehydrated and has difficulty performing activities that require energy. If your body doesn’t absorb enough water or electrolytes, it may become overly fatigued and unable to complete physical tasks. This can lead to increased feelings of sleepiness.

Signs that you may need to drink more fluids include fatigue, thirst, dry mouth, dark urine, dizziness or lightheadedness. Even mild dehydration can cause fatigue and impact your ability to stay awake during physical activities. In general, active individuals should hydrate with up to 6-8 glasses of water over the course of an hour in order to prevent dehydration and promote proper fluid balance while engaging in exercise or physical activity. Additionally, it is important to monitor sodium intake if sweating heavily during physical activity as sodium helps the body retain fluids better than drinking plain water alone. It is also important to include foods high in electrolytes such as bananas and oranges which will help replace lost electrolytes while hydrating at the same time.

Low Energy Levels

Physical activity can cause fatigue because it can temporarily reduce a person’s energy reserves. Fatigue is caused by the depletion of the body’s energy stores. This may include glycogen, the storage form of glucose, as well as other non-carbohydrate sources such as adenosine triphosphate (ATP) and creatine phosphate (CP). When these energy stores become depleted during strenuous physical activity, exhaustion or fatigue can set in.

In addition, intensive exercise also causes an increase in cortisol production – a hormone associated with stress that can contribute to fatigue. The production of cortisol and other hormones during exercise may also cause decreased heart rate and blood pressure which can further reduce energy levels and make you feel more sleepy or lethargic after your workout.

Low blood sugar can also contribute to post-exercise sleepiness. If you exercise for longer than an hour without taking in any additional carbohydrates then your stores of glycogen and other sugars become depleted putting you at risk for low blood sugar levels which will limit your performance and may contribute to decreased alertness after working out. A low body temperature has also been linked to lower alertness so if you’re pushing yourself too hard during your workout then you may find yourself feeling more tired afterward as your body attempts to recover from the exertion.

How to Avoid Exercise-induced Sleepiness

Working out can often cause sleepiness and fatigue due to the physical stress that it puts on the body. This fatigue can lead to a lack of motivation to continue exercising, or even make it harder to stay awake during the day. It is important to learn how to avoid exercise-induced sleepiness in order to maximize your workout results. Here are some tips to help you stay awake and energized when exercising.

Eat a Balanced Diet

One of the primary causes of exercise-induced sleepiness is poor nutrition. Eating a balanced diet that consists of fruit and vegetables, lean protein, whole grains, and healthy fats like those found in fish, nuts and avocados is important to maintain energy levels during exercise. Try to focus on complex carbs with a low glycemic index as they will provide sustained energy rather than a quick sugar spike. Additionally, pay attention to timing – avoiding exercise within two hours of eating can decrease sleepiness post-workout as digestion diverts the body’s resources away from working out effectively. Eating snacks an hour before a workout can help improve performance by providing fuel etc.

Stay Hydrated

Staying hydrated during and after exercise is one of the best ways to prevent yawning during exercise. Drinking entirely too much water or sports drinks can be unhealthy, so it’s important to stay balanced. The general rule of thumb is to take in about 8 ounces for every 15 minutes of moderate activity. This should increase depending on the intensity and type of exercises being done.

If you drink too little water or sweat a lot, your body can become overheated, which will lead to fatigue and an increased risk for getting injured or quickly becoming exhausted. To avoid this, it’s important to make sure you are hydrating in 4 different ways:

1) Prehydrate: Drink 16-24 ounces at least two hours before beginning strenuous activity
2) Take small sips: Throughout the duration of your workout think about taking small sips (even if it means slowing down briefly)
3) Afterward: Rehydrate within 30 minutes after a workout
4) Replenish lost electrolytes: Foods like Greek yogurt and bananas are great sources since they contain potassium which helps muscles work more efficiently while reducing fatigue

In addition, consider adding electrolyte powders or dissolve tablets into water to avoid any dehydration issues during activities that tend to make you tired like running, working out in the heat outside or engaging in an intense indoor cardio routine. By following these steps regularly and supplementing with electrolytes when needed, you’ll be well on your way feeling energized rather than exhausted from exercise!

Get Enough Sleep

Ensuring that you are getting adequate amounts of rest is key to keeping your energy levels high throughout the day. Adults between the ages of 26-64 should aim for 7-9 hours of sleep, according to the Centers for Disease Control and Prevention (CDC). Every individual is different and will require a different amount of sleep – so if you feel like you need more than 8 or 9, that’s ok too! Keep in mind that how much quality sleep you get is just as important as how long you are asleep. Other things to keep in mind when it comes to sleep are limiting screen time before bed, setting your bedroom conditions up optimize good sleep (cooler temperature, blackout curtains/blinds, limiting noise etc.), and avoiding stimulants such as caffeine late in the day. Consistently practicing good sleep hygiene will help ensure your body gets enough rest.

Take Breaks During Exercise

It’s natural and healthy to feel a bit tired after exercising, as your body is working hard to build strength and improve fitness. However, sudden and overwhelming fatigue during or shortly after a workout can be caused by exercise-induced sleepiness (EIS). To stay alert while exercising, it is important to understand what causes EIS so that you can make adjustments to prevent it.

One way to avoid exercise-induced sleepiness is to take regular breaks throughout your workout. Sticking to an intense exercise routine without breaking can cause your body to become overstimulated and lead to exhaustion. The amount of time and frequency of breaks depend on the type of exercise you are doing and the intensity level. Taking breaks every 15 minutes or so helps keep your energy up so that you don’t become too fatigued too quickly. It also gives you an opportunity for recovery and prevents exhaustion caused by overexertion.

Additionally, it’s important to make sure that you are eating a balanced diet with nutrient-rich foods before and after workouts. Avoid junk food as much as possible, as this will cause energy crashes later in the day which may lead to feeling sleepy during a workout session. Eating complex carbs with protein will help provide steady energy for physical activities instead of relying heavily on sugar for quick bursts of energy followed by inevitable fatigue. When it comes time for an exercise break, try snacking on fruits or nutrient-packed smoothies instead of unhealthy snacks like chips or candy bars, as they will give you more sustainable energy in the long run.


Exercise has many beneficial effects on the body and mind, including improving energy levels and aiding sleep. However, in some cases, people may feel tired after a workout. This is usually due to the body’s natural response to physical activity, which involves releasing hormones that increase fatigue. Other possible causes include dehydration, not getting enough sleep at night or eating certain foods before exercise.

If you’re feeling constantly fatigued after working out, it’s important to speak to your doctor or health care professional who can look into underlying factors that may be affecting your energy levels. If necessary, they may suggest changing up your exercise routine or making any necessary dietary changes in order to improve how you feel after exercise. Ensuring you stay hydrated and get enough rest between workouts can also help reduce fatigue afterwards and help keep you energized throughout the day.

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