When you hit the gym for a workout, you’re expecting to end up feeling energized and ready to tackle the rest of your day. Normally, that’s the case. Exercise triggers the release of endorphins, which makes you feel energized and upbeat. But sometimes, after a good workout you may find yourself feeling tired and sleepy instead. This can be confusing—you just completed an activity that is meant to raise your energy levels and make you feel great! Why do you feel ready for a nap? Let’s explore why you may be feeling sleepy after a workout and what you can do about it. We’ll also tell you whether or not you should nap, how to time your workouts, and some other tips to help you stay energized.
Why Do I Get Sleepy After Workout?
There are several possible explanations for why you might be feeling sleepy after a workout:
Research into how physical activity affects energy levels has found that exercise-induced fatigue is a real phenomenon (1). This refers to feeling tired and exhausted after a workout, rather than the energizing effects of exercise.
It’s believed that this fatigue is caused by a combination of factors, mainly changes in the nervous system.
There are two parts that make up the nervous system: the central and peripheral nervous systems. The peripheral nervous system controls movement, like when you’re lifting weights or running.
When you exercise, your peripheral nervous system is activated, causing an increase in heart rate, respiration, and blood flow. This causes your body to work harder than it normally would during restful activities (1).
The central nervous system regulates cognitive processes, like making decisions and thinking. When you exercise, the stimulation of your peripheral nervous system causes a decrease in your central nervous system activity. This can lead to a feeling of fatigue and sleepiness after a workout (1).
Some theories suggest that the fatigue we experience after a workout is due to our body’s natural protective mechanism, which kicks into gear when it senses that you have exerted too much energy (7).
Dehydration is a possible explanation for feeling sleepy after a workout. When you exercise, you’re sweating and losing fluids, which can lead to dehydration. Dehydration is characterized by fatigue, dizziness, and headache among other symptoms (2).
In a small study, researchers found that dehydration caused by exercise was associated with an overall decrease in cognitive performance (4). This suggests that not drinking enough fluids after a workout can affect your mental alertness and contribute to feeling sleepy.
Low Blood Sugar
Low blood sugar is another possible explanation for feeling fatigued after a workout (6). When you exercise, your body uses up its stored sugar (glycogen) for energy.
If you don’t refuel with carbohydrates after your workout, your blood sugar levels can drop, causing a feeling of fatigue and sleepiness.
If you’re not eating enough in general too, this could contribute to low blood sugar and make you feel sleepy after a workout. This is especially true if you’re eating below your basal metabolic rate, which is the amount of energy (calories) you need to perform basic body functions.
Lack Of Sleep
Research shows that even one night of poor sleep can lead to increased fatigue, impaired cognitive functioning, and decreased motivation the next day (10). It could take a toll on your energy levels and cause post-workout drowsiness.
Poor sleep habits accumulate over time—if you’re consistently not getting enough sleep, it could be causing a greater feeling of fatigue than usual.
What you eat has a huge influence on your energy levels. Eating a diet that’s low in nutrients or highly processed can make you feel tired, even after a workout. Your choice of pre- and post-workout snacks can also affect your energy levels.
Eating snacks that contain simple carbohydrates, like bananas and granola bars, or protein shakes can help replenish lost energy and keep you energized throughout the day.
Overtraining syndrome (OTS) is a condition where you’re working out too often and too intensely, leading to decreased performance and increased fatigue.
OTS can lead to feeling tired after a workout or even during it. Some tell-tale signs of OTS include sleep disturbances, loss of appetite, decreased motivation to exercise, and mood changes. Over time, it can lead to more serious consequences, like an increased risk of injury (9).
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Can I Sleep After A Workout?
There are some pros and cons to taking a nap after a workout:
A nap can be a refreshing way to recharge your batteries after a workout. It can also help you recover by restoring energy, replenishing glycogen stores, and repairing muscle damage sustained during exercise.
Napping too much or for too long can disrupt your natural circadian rhythm and make it harder to fall asleep at night. Additionally, naps can sometimes lead to sleep inertia, which is a feeling of grogginess and disorientation (11).
How Much Sleep After Workout?
The optimal amount of sleep after a workout is based on the National Sleep Foundation’s recommended nap guidelines.
The National Sleep Foundation recommends that power naps (naps lasting between 10 and 20 minutes) should be taken no more than three times a week, with the ideal nap time being between 1 pm and 3 pm (8). This allows you to get the benefits of a refreshing nap without disrupting your sleep cycle too much.
If you need more than 20 minutes of sleep to feel rested, you should opt for 90 minutes of sleep instead (i). This is known as a “recuperative nap” and can help restore your energy levels while avoiding the sleep inertia associated with longer naps.
How To Prevent Feeling Sleepy After A Workout
If you’re feeling sleepy after a workout, there are some things you can do to help:
Hydrate Before And After Your Workout
Make sure you’re drinking enough water throughout the day and before and after your workout. This will help prevent dehydration, which can lead to fatigue and sleepiness after a workout.
The recommended daily water intake for adults is 2.7 liters (about 91 ounces). However, if you’re exercising, you should be drinking up to 3.7 liters (about 125 ounces) per day (12).
Eat Enough To Fuel Your Workouts
Make sure you’re eating enough calories and nutrients to fuel your workouts. This means making sure you’re getting enough protein, carbohydrates, healthy fats, vitamins and minerals in your diet.
Eating nutrient-dense snacks before and after your workout can help keep you energized throughout the day.
Some of the best pre-and post-workout snacks include yogurt with fruit, trail mix, energy bars, peanut butter on toast, or a protein shake.
Taking a daily multivitamin or supplementing with specific vitamins and minerals, such as B-complex vitamins, iron and magnesium can help increase your energy levels.
However, it’s important to talk to your doctor before taking any supplements, as taking too much of certain vitamins and minerals can be dangerous.
Get Enough Sleep At Night
One of the best ways to make sure you have enough energy for a workout is by getting enough sleep at night. The National Sleep Foundation recommends that adults get 7-9 hours of sleep each night (5).
Consistently getting enough sleep will help you feel more energized throughout the day and better able to handle an intense workout.
Below are some sleep hygiene tips that can help you get a good night’s rest:
- Avoid screens (phones, computers, TVs) for at least an hour before bedtime.
- Create a relaxing sleep ritual like listening to soothing music or reading a book.
- Make sure your bedroom is dark, quiet and cool.
- Avoid large meals or caffeine close to bedtime.
- Exercise regularly and get plenty of natural sunlight during the day.
Review Your Workout Routine
If you’re constantly feeling sleepy after a workout, it may be time to review your routine. Make sure you’re not pushing yourself too hard. It’s important to recognize when your body needs a break and adjust the intensity of your workouts accordingly.
A good rule of thumb is to start out with a lower intensity and gradually increase the difficulty as your body adjusts. Rest days are also important and should be worked into your routine.
For starters, aim for 2-3 rest days each week. During these days, you can focus on stretching, foam rolling or other restorative activities.
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Cool Down After Your Workout
Cooling down after a workout is an important part of recovery. It serves multiple purposes, including allowing your body to gradually transition from an intense activity to a resting state. It also helps reduce lactic acid buildup in your muscles and improve flexibility (3).
A cool-down should last for 5-10 minutes and can include light stretching, foam rolling or a slow jog or walk. This may help reduce the risk of feeling sleepy after a workout, as your body will be better able to transition back into a resting state without feeling too fatigued.
Taking a nap after a workout can be beneficial in restoring energy, replenishing glycogen stores and repairing muscle damage. However, it is important to know your own limits and not exceed the recommended nap guidelines.
Additionally, following good sleep hygiene practices and eating enough to fuel your workouts can help you get the most out of your workout without feeling overly tired afterwards.
This article is intended for general informational purposes only and does not address individual circumstances. It is not a substitute for professional advice or help and should not be relied on to make decisions of any kind. Any action you take upon the information presented in this article is strictly at your own risk and responsibility!
- Central and Peripheral Fatigue in Physical Exercise Explained: A Narrative Review (2022, nih.gov)
- Dehydration Headache (2021, clevelandclinic.org)
- Do We Need a Cool-Down After Exercise? A Narrative Review of the Psychophysiological Effects and the Effects on Performance, Injuries and the Long-Term Adaptive Response (2018, nih.gov)
- Effects of Dehydration and Rehydration on Cognitive Performance and Mood among Male College Students in Cangzhou, China: A Self-Controlled Trial (2019, nih.gov)
- How Much Sleep Do We Really Need? (2023, sleepfoundation.org)
- Hypoglycemia (2022, mayoclinic.org)
- Muscle fatigue: general understanding and treatment (2017, nih.gov)
- Napping: Benefits and Tips (2023, sleepfoundation.org)
- Overtraining Syndrome (2012, nih.gov)
- Sleep deprivation: Impact on cognitive performance (2007, nih.gov)
- Sleep Inertia (2023, sleepfoundation.org)
- Water: How much should you drink every day? (2022, mayoclinic.org)