Sleep And Dehydration (Are They Related?)

Sleep and Dehydration

A few days ago I went for a late-night run before I went to bed. It had been a long day of staring at the computer. I was feeling quite restless and realized I needed to do some physical activity before trying to sleep. After a quick 5km run, I was feeling much better, got ready for bed and went to sleep. The next morning I woke up quite groggy with a headache and a dry mouth. I began to retrace my steps from the day before and started to wonder if there was a relationship between dehydration and sleep. 

After doing some research, I found that there is a strong connection between dehydration, the impact it has on your sleep pattern, and how you feel when you wake up the next morning.

In this article we’ll discuss the relation between dehydration and sleep, as well as answering the following common questions:

  • Can a shorter or longer sleep lead to dehydration?
  • Reasons why you wake up dehydrated every morning? 
  • How to prevent dehydration during sleep?

Can A Shorter Or Longer Sleep Lead To Dehydration?

When I have a poor, or short sleep, I wake up with a headache and not feeling refreshed in the morning.

I have always associated this groggy feeling with a poor sleep, but I have never actually given much thought to why I wake up with a headache. Have you ever wondered if the length of your sleep has a direct effect on your hydration?

Well, a recent study conducted by Asher Y Rosinger from the Pennsylvania State University researched how the length of sleep can impact your body’s hydration levels.

The study was conducted between adults from both the United States and China, who were all over the age of 19. It took into account the length of sleep an individual received and their urine specific gravity.

According to an article by Healthline, a urine specific gravity test compares the density of an individual’s urine, to the density of water. A urine specific gravity test is an easy way to determine your hydration levels, amongst other things.

Typically a urine specific gravity of greater than 1.010 can mean you are mildly dehydrated. Urine specific gravity values from the study ranged from 1.0 to 1.04. The study considered anything greater than 1.02 to represent inadequate hydration.

Results showed that those who slept 6 or less hours a night had a higher urine specific gravity than those who slept 8 hours a night.

As the research paper stated, “Short sleep duration was associated with higher odds of inadequate hydration in US and Chinese adults relative to sleeping 8 hr.”

That being said, there weren’t any consistent results that could be related to urine specific gravity values and those who slept for 9 or more hours.

So next time you have a poor sleep and wake up feeling groggy, it is even more important to hydrate. As it was concluded in the research study, a poor sleep does have an impact on your body’s hydration levels.

Reasons Why You Wake Up Dehydrated Every Morning?

There are several different reasons why you can wake up feeling dehydrated.

For starters, the definition of dehydration, in its most basic form, is a lack of water in your body. A lack of water in your body is a result of your body losing more fluid than it is receiving.

When you are asleep, you have no way of drinking or obtaining fluids. Therefore, it is natural for your body to lose more water than it receives during sleep.

However, this doesn’t mean you should wake up feeling gross each morning. Later on in the article, I’ll give you some tips on how to prevent dehydration during sleep.

For now, I’ll discuss some reasons why you might be waking up dehydrated.

1. Breathing

Regardless of other factors that might influence why you wake up feeling dehydrated, you lose some fluids every night from breathing. This is natural and happens when you exhale.

As you exhale, water, in the form of vapor, leaves your body. Furthermore, you lose a lot more water while sleeping if you breathe through your mouth instead of your nose.

Waking up with a dry mouth can mean you were breathing through your mouth while sleeping. This can further dehydrate you.

Your nose was designed to retain moisture, and you should aim to breathe through it while sleeping. The best way to breathe through your nose is sleeping on your back and having your head slightly elevated.

This will also help to prevent snoring if your nose is clear and unstuffed.

2. Exercising Too Late

Exercising is a great stress reliever at the end of a busy day. Taking out your daily frustrations by increasing your heart rate at the gym, or while on a run is a healthy way to relieve stress.

As previously discussed, fluid loss is greatly increased during exercise, and even more so during intense exercise. It is important to replenish the lost fluids before (in anticipation), as well as during and after your exercise.

If you exercise too close to when you head to bed, it will impact your sleep in a few different ways. For starters, it will take you longer to get to sleep as your body comes down from being all worked-up from your late-night exercise.

Additionally, you need to give your body a sufficient amount of time to rehydrate after exercise. If you go to bed dehydrated, chances are you’ll have a poor sleep and wake up feeling even worse in the morning.

A product I recommend is Liquid I.V. Hydration Multiplier. It helps you hydrate more efficiently, and effectively than water alone. Furthermore, it is great for replenishing lost fluids after an intense exercise.

You can find it on Amazon here. Or you can read the article we recently wrote, Best Hydration Drinks For Runners, where we discuss the benefits of Liquid I.V. and other hydration drink alternatives.

3. Sickness

Fluid loss from your body is greatly increased in hot weather, during exercise, and when you are sick. I’ll focus on the latter in this section.

When you are sick (and awake), your body loses more fluids than normal from the side effects of being sick. This can include having diarrhea, blowing your nose, and sneezing.

You have probably been told to ‘stay hydrated’ when sick, this is why! While some of these side effects might still occur when you are sleeping, a more common side effect is night sweats.

When you have a fever or high body temperature, your body sweats to try and cool itself down. Night sweats are another way you lose fluids and can become dehydrated while sleeping.

4. Too Hot While Sleeping

You don’t always have to be sick to sweat while sleeping. Your body can become too hot while sleeping for a number of different reasons. Such as your bedroom is too hot, the geographic location you live in has a warmer climate, or it is during the summer months.

As previously discussed, as your body becomes too hot while sleeping, it will start sweating to try and regulate the temperature and cool down. This could leave you waking up with symptoms of mild dehydration.

If you get too hot while sleeping, consider buying a fan, cracking the window open for some fresh air, wearing fewer layers to bed, or even buying a humidifier in dry climates.

5. Consume Too Much Alcohol

Excessive alcohol consumption might very well help you get to sleep, but it won’t do much for helping you stay hydrated. As many know, alcohol is a diuretic, which increases urine production in your body.

As your body produces more urine, it needs to dispose of it more frequently. In addition to the poor sleep you are probably already having from the impacts of excessive alcohol consumption, you will now be waking up throughout the night to go pee.

How To Prevent Dehydration During Sleep?

The best way to prevent waking up feeling dehydrated is to consume non-caffeinated fluids at regular intervals throughout the day. This will not only prevent you from waking up feeling dehydrated, but it will promote a healthier lifestyle overall.

With our bodies made up of over 60% water, it is important that we replenish lost fluids so we continue to function properly. Hydrating regularly throughout the day will help you have a more complete sleep at night.

In addition, you will wake up feeling more awake, and attentive throughout your day.

Recommended Products

Check-out the list of the products we recommend to help keep you hydrated throughout your day.

That being said, there are some other points we should mention that can help prevent dehydration during sleep (some already discussed in this article). These include:

  • Avoid caffeine in the evening
    • Caffeinated beverages can have diuretic effects, causing you to urinate more frequently throughout the night.
  • Minimize dinners and nighttime snacks that are high in sodium.
    • Foods that are high in sodium, more commonly known as salt, make you thirsty. It is important to quench your thirst during and after eating food that has a high sodium content. Otherwise, your body will quench this thirst by drawing liquid from other parts of your body. This can lead to mild dehydration. If you are snacking late at night, this might not be apparent until you wake up the next morning.
  • Avoid excessive alcohol consumption.
    • As previously discussed, alcohol is a diuretic and will cause you to go to the bathroom more frequently throughout the night. Additionally, other side effects of alcohol can lead to headaches, thirst, and a dry mouth that will further dehydrate you while sleeping.
  • Don’t exercise too late at night.
    • If you head to bed shortly after an intense exercise, you aren’t giving your body enough time to rehydrate. Adequate hydration after exercise is important for a restful sleep.
  • Help monitor the temperature in your bedroom by sleeping with a fan on or your window open.
    • Struggling to regulate your body temperature while sleeping (not just when sick) is common. Many people go to sleep slightly cold (pile on extra layers) and wake up too hot (sweating). Fluid loss from sweating while sleeping can have you waking up feeling dehydrated.  


In this article, we looked at the connection between dehydration and sleep. Firstly I discussed a research study conducted by Asher Y Rosinger from Pennsylvania State University.

It concluded that those who had a shorter sleep (6 hours or less) had higher odds of being inadequately hydrated than individuals who received 8 hours of sleep.

Next, I discussed some reasons why you wake up dehydrated each morning, and what you can do to prevent it. These included avoiding caffeine in the evening, minimizing late-night snacks that are high in sodium, avoiding excessive alcohol consumption, and not exercising too late at night.

For any comments, questions or feedback you might have, please send us a message through our contact form.


Facts for this article are referenced from credible sources. For further information, please read these referenced articles from the following organizations:

Be sure to consult your health care professional with any medical questions. Similarly, the information found in this article should not be considered medical advice.

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