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Is dehydration ruining your sleep?

June 29, 2023 - 19 min read
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    Water is an essential component of our overall health. It makes up a significant portion of our bodies and plays a crucial role in various bodily functions. Every cell, tissue, and organ requires water to function properly. So adequate daily hydration is essential for good health—and sleep.

    While we often associate hydration with diet and exercise, or hot summer days, recent studies have shed light on the connection between hydration and sleep. It turns out that dehydration can hinder our ability to sleep well, and insufficient sleep can, in turn, increase the risk of dehydration.

    Let’s look at the hydration-sleep connection from both angles. But first, what does dehydration feel like, and how do we become dehydrated?

    Are you dehydrated before bed?

    When you’re dehydrated, you’ll likely feel logy, sluggish, fatigued, and headache-prone. If you’re thinking that sounds remarkably like how you feel when you’re sleep deprived, you are correct... and the correlation doesn’t end there.

    Being even mildly dehydrated when you crawl into bed can impact your natural circadian rhythm, causing sleep disruptions followed by sleepiness the following day. And while dehydration may create barriers to sleep, insufficient sleep may also increase your chances of being dehydrated. It’s a two-way street.

    Why do we become dehydrated while sleeping?

    Beyond the simple answer of not drinking enough water during the day, dehydration can occur for several other reasons. One of them is simply the fact that we go without water for several hours while we sleep. Additionally, our bodies continue to lose water through various processes, such as breathing and perspiration, during our sleep cycles. So, by the time we wake up, we are already starting the day with a hydration deficit.

    But that's not the only reason that you might wake up dehydrated. Another culprit is dehydration itself. Even if you don't engage in intense physical activity or spend a lot of time in the sun, you can still become dehydrated during the day. 

    When we are dehydrated, our bodies struggle to maintain proper fluid balance, and this can have negative effects on our sleep cycle. Over time, our skin becomes dry, and our bodies may struggle to regulate temperature effectively, leading to disrupted sleep patterns.

    How dehydration can disrupt sleep

    Even though your body is mostly still while you sleep, physiologically, it’s very active. During REM sleep, your brain consolidates memories and learning; deep sleep is when your body restores chemical balances, recovers, and heals. Because water is essential for every one of our body’s functions, being dehydrated when you flip off the lights can affect the multiple complex processes your body follows to repair itself as you sleep.

    There are several other ways dehydration can disrupt healthy, restful sleep:

    • Muscle cramping: Nocturnal leg cramps of the calf or foot muscles, which can wake you up in the middle of the night, are often a symptom of dehydration. Dehydration can also trigger muscle spasms, making it hard to fall asleep or potentially waking you up. 
    • Headaches:  Headaches and migraines can complicate falling asleep and staying asleep. Dehydration headaches may be caused by the brain temporarily contracting or shrinking due to fluid loss and electrolyte imbalance. This action of the brain pulling away from the skull can potentially cause pain.
    • Early morning thirst: Being thirsty can wake you up in the middle of the night, or too early in the morning.
    • Dry mouth: A dry mouth and nasal passageways can cause discomfort and aggravate sleep. Occasionally it can cause snoring, even if you’re not typically a snorer, waking you up at night.
    • Dehydration can also affect melatonin: Melatonin is a sleep hormone that plays a key role in regulating your natural sleep cycle. Chronic dehydration reduces the presence of amino acids in your body that produce melatonin. Without enough melatonin, you may not get sleepy at night, and it may take longer to fall asleep. Melatonin also plays an indirect role in the metabolism of water and electrolytes. If you don’t have enough melatonin because you’re dehydrated, your sleep may suffer even more. Even being slightly dehydrated can lead to lighter sleep.

    How poor sleep can worsen dehydration

    Though sleep experts have a pretty good handle on how dehydration can upend a restful night, scientists have only recently begun exploring how a lack of sleep may contribute to dehydration.

    Interestingly, research has shown that too little sleep may also contribute to dehydration. A recent study found that inadequate sleep can lead to increased water loss and higher levels of dehydration. This highlights the importance of getting enough sleep not only for our overall well-being but also for maintaining proper hydration levels.

    The study looked at data from more than 20,000 healthy young adults from the U.S. and China. It found that those who self-reported sleeping 6 hours or less per night had significantly higher rates of dehydration (as measured by urine samples) than those who regularly logged 8 hours or more.

    In both populations, those who reported sleeping 6 or fewer hours had up to a 59% higher risk of dehydration compared with those who slept 7 to 8 hours on a regular basis.

    The researchers speculated that their findings could reflect the nightly rhythm of a hormone called vasopressin.

    Here’s their thinking:

    During sleep, we don’t take in any fluid to make up for what’s lost through insensible water loss, which refers to normal respiration and other bodily processes. So our circadian rhythm kicks in to manage a balanced level of hydration.  In the latter part of sleep, circadian signals tell the body to produce an antidiuretic hormone called vasopressin, which promotes water retention. If sleep is interrupted or cut short, this natural process may also be disrupted, interfering with the hormonal signals. 

    As a result, sleep deprivation may directly contribute to dehydration.

    Commenting on the findings, the lead author noted, “If you are only getting 6 hours of sleep a night, it can affect your hydration status.” The findings, published online by the journal Sleep, suggest that the symptoms we experience the next day and think are from inadequate sleep—fatigue, fuzzy thinking, and morning headaches—may be due to dehydration.

    womans hand carrying metal water bottle to stay hydraeted

    Tips for staying hydrated and promoting better sleep

    It happens. You realize the day has slipped away with barely a sip of water. In those cases, you don’t want to chug a day’s worth of fluid right before bed unless you want to make late-night runs to the restroom. Disrupted sleep can take a toll on your energy, performance, and mood the next day.

    To help avoid the disruptions, here are a few tips to stay properly hydrated and get your best rest:

    Focus on good sleep

    Getting an adequate amount of high-quality sleep should be a priority. Sleep plays a crucial role in allowing the body to recover and function optimally. To ensure a good sleep, establish a consistent sleep schedule that allows for enough sleep time. Limit the use of electronic devices before bed, develop a relaxing bedtime routine, and create a comfortable sleep environment with a supportive mattress.

    Hydrate throughout the day

    To avoid feeling thirsty at night, it's important to stay hydrated throughout the day. Make it a habit to sip fluids regularly, and consider using a refillable water bottle to track your water intake. Schedule reminders if you need to.  The old rule of thumb used to be 8 glasses of water per day, but new National Academy of Medicine guidelines suggest that men drink around 125 ounces (about 15 cups) and women, 91 ounces (about 11 cups). That may seem like a lot, but it also includes water from foods you consume. Plus, the amount you need depends on your weight, height, level of exercise, and diet, so talk with your doctor to figure out the right amount for you.

    Drink up first thing in the morning

    Some sleep experts recommend starting the day with 20 oz. of water first thing in the morning to kickstart your hydration. We naturally lose fluids and electrolytes overnight through normal respiration—more if you’re a hot sleeper, have night sweats, or obstructive sleep apnea (OSA). You’ll also lose more fluid if you’ve worked out close to bedtime without rehydrating or have had a few nightcaps before going to bed.

    Make water your primary beverage

    Drinking water should be your primary beverage while moderating the consumption of sugary drinks, caffeinated beverages, and alcohol. They’re all diuretics and can interfere with your sleep cycle.

    Keep a reusable water bottle close by

    For convenience, and also to monitor your water during the day, keep a refillable bottle nearby. If you have a 20-oz water bottle, for instance, it’s easy to do the math and keep track of your daily fluid intake.

    Include lots of fruits and vegetables in your diet

    Incorporating a balanced diet rich in fruits and vegetables can increase your overall water intake. Many whole foods have a high water content, which counts toward your hydration goals. They are also full of electrolytes like potassium and sodium, which are important for properly hydrating your body.

    Maintain a comfortable bedroom temperature

    Nighttime sweating can contribute to water loss, potentially leading to dehydration. To prevent excessive sweating, ensure that your bedroom temperature is cool and comfortable. Experts recommend keeping the thermostat on the cooler side, wearing light and breathable clothing, and using bedding materials that promote airflow and prevent overheating. According to the Sleep Foundation, the ideal bedroom temperature for most people is around 65 degrees (or a range between 60 to 67 degrees) Fahrenheit.

    Manage fluid intake before bed

    To minimize the need to wake up frequently to use the bathroom, it's advisable to reduce fluid consumption one or two hours before bedtime. While sipping water is fine, avoid consuming large quantities of any beverage close to bedtime. 

    Limiting alcohol and caffeine intake in the evening is also important, as both can have a diuretic effect and disrupt sleep. It's also helpful to empty your bladder before going to bed to reduce the likelihood of waking up to visit the restroom during the night.

    Develop strategies for falling back asleep

    If you do need to wake up to use the bathroom during the night, it's important to make it as easy as possible to fall back asleep. Here are some tips to help you return to sleep quickly:

    • Use a low-wattage or motion-activated night light to navigate your way to the bathroom without fully waking up.
    • Keep the path to the bathroom clear of any hazards that could cause you to trip or stumble.
    • Resist the urge to check your phone or other electronic devices, as the blue light can interfere with your ability to fall back asleep.
    • Create a sleep-friendly environment by blocking out excess light and sound using a sleep mask, white noise machine, or earplugs if necessary.
    • Practice relaxation techniques such as deep breathing to calm your mind and body.

    Consult with a doctor

    If you have concerns about dehydration, poor sleep, or frequent nighttime trips to the bathroom, it's advisable to consult with a doctor. They can review your situation and determine if any underlying medical conditions may be contributing to your symptoms. Your doctor can also provide specific recommendations for your diet and daily water consumption.

    man of color drinking water on a track to stay hydrated

    Sleep and dehydration FAQs

    Can dehydration cause insomnia?

    Dehydration can indeed have an impact on our sleep patterns, but it may not directly cause insomnia. According to the Sleep Foundation, dehydration can create barriers to sleep, and insufficient sleep can increase the chances of becoming dehydrated. However, there is currently no evidence suggesting that mild dehydration directly causes insomnia or other sleep disorders.

    How can I tell if I’m waking up dehydrated?

    There are several signs and symptoms that can indicate you're waking up dehydrated. Here are some common indicators:

    • Dry mouth and throat: Waking up with a parched or sticky feeling in your mouth and throat is a typical sign of dehydration.
    • Fatigue and lethargy: Dehydration can lead to feelings of fatigue, low energy, and general lethargy upon waking up. If you consistently feel tired despite getting adequate sleep, dehydration could be a contributing factor.
    • Thirst: Feeling thirsty upon waking up is a clear indication that your body needs hydration. Your body's thirst mechanism is a natural response to insufficient water levels.
    • Headache: Dehydration can cause headaches, including morning headaches. If you frequently wake up with a headache that subsides after hydrating, it could be a sign of dehydration.
    • Dark urine: The color of your urine can be an indicator of hydration levels. If you wake up with urine that is dark yellow or amber in color, it suggests that you may be dehydrated.
    • Dry skin and lips: Dehydration can affect your skin and lips, making them feel dry, tight, or cracked when you wake up.
    • Reduced urine output: Monitoring your urine output can give you clues about your hydration status. If you notice a decrease in the amount of urine you produce or infrequent bathroom visits, it may indicate dehydration.

    It's important to note that these symptoms can also be associated with other health conditions. If you consistently experience these symptoms or have concerns about your hydration status, it's advisable to consult a healthcare professional for proper evaluation and guidance.

    Does waking up dehydrated make you tired?

    Yes, waking up dehydrated can contribute to feelings of fatigue and tiredness. Water is essential for maintaining proper blood circulation and delivering oxygen and nutrients to your muscles and organs. When you're dehydrated, your blood volume decreases, which can result in reduced oxygen supply to your tissues and organs, including your brain. This can lead to feelings of fatigue, lack of energy, and difficulty concentrating or staying alert.

    Can you prevent dehydration when you sleep?

    You may not prevent it entirely, but here are some things you can do to help:

    • Stay hydrated throughout the day: Make it a habit to drink an adequate amount of water and hydrating fluids throughout the day, even before bedtime. This helps ensure that your body starts the night well-hydrated.
    • Limit caffeine and alcohol intake: Both caffeine and alcohol have diuretic properties, which can increase urine production and lead to dehydration. Avoid consuming these substances close to bedtime to minimize their dehydrating effects during sleep.
    • Use a humidifier: Dry indoor air can contribute to increased water loss from your body during sleep. Using a humidifier in your bedroom can help maintain a more humid environment, reducing the risk of dehydration.
    • Monitor bedroom temperature: High temperatures can promote sweating and fluid loss during sleep. Set your bedroom temperature to a comfortable level that prevents excessive perspiration and dehydration.
    • Hydrate before bed: Drink a glass of water or a hydrating beverage shortly before going to bed. This can help replenish your fluid levels and reduce the chances of waking up dehydrated.
    • Consider electrolyte-rich beverages: In addition to water, consuming fluids that contain electrolytes, such as sports drinks or coconut water, can help replenish both water and essential minerals in your body. These electrolytes aid in maintaining proper hydration and electrolyte balance.

    You can improve your sleep by preventing dehydration

    Hydration plays a crucial role in our overall health, including our sleep quality. Dehydration can disrupt sleep and lead to symptoms such as fatigue, muscle spasms, headaches, and dry mouth. Conversely, insufficient sleep can contribute to dehydration. To maintain proper hydration and promote better sleep, it's important to focus on good sleep hygiene, stay hydrated throughout the day, manage fluid intake before bed, and implement strategies for falling back asleep if necessary. By finding the right balance, you can improve your overall health and enjoy a restful night's sleep without the discomfort of dehydration or frequent trips to the bathroom.

    Enhance your health and wellness

    Create a plan for a healthier life with personalized guidance from our wellness coaches.

    Published June 29, 2023

    Janet Ungless

    Janet Ungless is a health and wellness writer specializing in sleep, meditation, and mindfulness. Her work has been featured on Sleep.com, Crescent Health, Oura, Headspace, and Casper. Janet holds a Bachelor of Arts in English from the University of Pennsylvania.

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