If you experience insomnia, it could be due to the symptoms of dehydration. Dehydration can cause headaches, dry mouth, and muscle cramps that may interfere with sleep. Treatment can help.

Your daily water intake contributes to your overall well-being. If you don’t drink enough, you could experience symptoms such as headaches, weakness, and dizziness.

These symptoms can interfere with your ability to sleep well. Although dehydration isn’t a direct cause of insomnia, it can contribute to poor sleep.

This article explores how dehydration affects sleep.

Symptoms of dehydration can appear at night and interfere with the duration and quality of your sleep. One obvious example is waking up in the middle of the night feeling thirsty. If you have to get up to drink water, you might struggle to fall back asleep afterward.

Other side effects of dehydration — such as headaches and muscle cramps and spasms — can also keep you awake.

Aside from these disruptive symptoms, there are no clear links between hydration levels and insomnia. And there’s very little research on the topic.

Symptoms of dehydration

  • dry mouth
  • extreme thirst
  • lightheadedness
  • dark-colored or strong-smelling urine
  • urinating less often than usual
  • fatigue

One of the largest studies on hydration and sleep, conducted in 2018, included more than 20,000 adults in the United States and China.

The authors found that participants who reported sleeping only 6 hours per night were more likely to show signs of inadequate hydration than those who reported sleeping 8 hours per night.

Similarly, the authors of a very small 2023 pilot study reported that participants who were adequately hydrated showed slightly higher levels of sleep efficiency than those who were dehydrated.

In contrast, a very small 2018 study found that participants’ hydration status did not affect their sleep.

More studies are needed to understand how fluid intake affects sleep quality and quantity.

There are many possible causes of nighttime dehydration, including:

  • Alcohol: Dehydration is a common side effect of alcohol consumption.
  • Exercise: When you exercise, your body loses extra fluids through sweat.
  • Heat and humidity: Heat is a common cause of dehydration, particularly in older adults. If your bedroom is too dry, this can also make you thirsty.
  • Medical conditions: If you have diabetes and your blood sugar levels are high, you’ll be more thirsty than usual. Fever, vomiting, diarrhea, and kidney problems can also increase thirst.
  • Medications: Some medications, like diuretics, make you urinate more than usual, increasing your risk of dehydration. Other common medications cause dry mouth as a side effect.
  • Night sweats: Night sweats can be a symptom of menopause, but can also indicate a significant medical issue and should be evaluated by a doctor.

If you think dehydration is contributing to poor sleep, the best way to treat it is to increase your water intake throughout the day. You may want to try some of these strategies:

  • Keep water with you at all times: It’s easier to remember to drink water if you always have a refillable water bottle with you.
  • Use a hydration app: If you find it difficult to drink enough water, a hydration app can provide reminders throughout the day.
  • Choose water: While liquids such as herbal tea, juice, and broth can all contribute to your daily fluid intake, water should be your go-to drink most of the time.
  • Drink before, during, and after exercise: You can avoid exercise-related dehydration by increasing your water intake even before you start physical activity.
  • Limit caffeine and alcohol: Caffeinated drinks and alcohol are OK in moderation, but to stay hydrated, be sure to drink water too.
  • Check your medications: If you suspect that diuretics are contributing to dehydration at night, talk with a healthcare professional about the best course of action.
  • Treat medical conditions: Keeping medical conditions such as diabetes, kidney disease, and Sjögren’s syndrome in check can help you avoid dry mouth and related symptoms at night.
  • Keep your bedroom cool: To avoid sweating too much in your sleep, keep your bedroom around 65°F (18.3°C) at night whenever possible.

These are some commonly asked questions about dehydration.

Do electrolytes help you sleep?

Electrolytes are minerals that you get from your diet, such as magnesium, potassium, and sodium. They help your body function at its best.

Electrolyte imbalances can interfere with the quality of your sleep. For example, low sodium levels have been linked to restlessness and difficulty sleeping.

Another example is calcium, which helps your body regulate slow-wave or deep sleep. A 2022 study suggested a link between low calcium levels and sleep disruption among shift workers.

You can maintain an ideal electrolyte balance by drinking enough fluids and eating a varied diet.

Why does alcohol cause dehydration?

Dehydration is a common side effect of alcohol consumption. That’s because alcohol reduces the release of the hormone vasopressin, which helps regulate urination.

When you drink alcohol, you urinate more often than you usually would. Drinking too much alcohol before bed can lead to symptoms of dehydration at night, such as dry mouth, thirst, and a throbbing headache.

Dehydration doesn’t necessarily cause insomnia, but the symptoms can disrupt your sleep. Common symptoms of dehydration include thirst, headaches, and dry mouth.

You may experience nighttime dehydration if you’re not taking in enough fluids throughout the day. Other common contributors to dehydration include alcohol consumption, hot weather, medications, and diabetes.

If you think dehydration is interfering with your sleep, try increasing your water intake throughout the day.