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How a Glass of Water Can Improve Your Sleep

Every day, it seems, there’s a new brand of water on the market, touting a unique benefit: SmartWater (it’s good for your brain!), Karma Water (it’s got healthy probiotics for your gut!), Sakara Beauty Water (it will make your skin glow!), Madame Dry Lightly Sparkled Rose Water (it’s filtered through rose quartz crystals for “compassion and clarity”—and Gwyneth Paltrow drinks it!).

But there’s one big benefit of drinking water that none of these fancy brands mentions: It can help you sleep better.

“We have all heard that hydration can help us function better throughout the day, but it is also important for a good night’s rest,” says Kristamarie Collman, MD, family medicine physician in Atlanta. When you skip out on drinking water during the day, you leave yourself open to a host of sleep disruptions at night. Here’s how hydration (or lack of it) affects your sleep—and how to ensure you’re getting the water you need.

The connection between drinking water and sleep

You might be wondering how, exactly, water plays a role in how well you sleep. It’s simple: When you’re not drinking enough water, you can become dehydrated. Here are just some of the ways being dehydrated can interfere with a good night’s sleep:

Nighttime leg cramps. Dehydration increases your risk of leg cramps. The risk is especially high if you exercise a lot or live somewhere very hot, because the more you sweat, the more fluids and electrolytes you lose—and that can cause your muscles to cramp up, explains Julie Rothenberg, RD, licensed dietitian in Miami.

Snoring. “Not ingesting enough fluids can dry up your nasal passages and lead to snoring at night, which can not only make your sleep worse but also ruin your partner’s sleep,” says Chris Brantner, certified sleep science coach and founder of SleepZoo. (If you or your partner has a serious snoring issue, check in with your doctor to make you don’t have sleep apnea, a potentially dangerous health condition. Here’s how to sleep better with sleep apnea.)

High blood pressure. “Sometimes dehydration can cause you to have high blood pressure, because your blood vessels are working harder to pump out blood—and that can cause trouble falling asleep,” says Rothenberg. A 2015 study published in the journal Hypertension found that people with chronic insomnia were more likely to have high blood pressure. They also took longer to fall asleep (14 more minutes) compared with the “normal” sleepers in the study.

Excessive thirst. You may wake up thirsty in the middle of the night if you don’t drink enough water during the day, says Samantha Scruggs, RDN, licensed dietitian in Charlotte, North Carolina.

Brain fog. When you don’t down enough H2O, expect to feel sluggish the next day. “Proper fluid intake may also improve your brain function throughout the night, so that you have improved alertness and energy the next day,” adds Collman.

Signs you may not be drinking enough water

Potential sleep problems aside, pay attention to these other signals that you may need to up your water intake.

  • Dark urine. A telltale sign of dehydration.
  • Dry skin. “Even if you use moisturizer, you’ll find your skin remaining dry if you’re not properly hydrated,” says Brantner.
  • Trouble focusing. “Dehydration has a negative impact on the blood supply to your brain,” Brantner says. “When this occurs, you will find yourself foggy-headed and not able to easily concentrate.”
  • Headaches. These are also linked to blood supply issues.
  • Fatigue. “Dehydration makes the heart work harder to pump blood out to muscles, which can lead to fatigue,” says Brantner. (Take our quiz to learn how sleep deprived you really are.)

How to drink enough water (without waking up to pee)

That whole “you have to drink eight glasses of water a day” advice you’ve always heard is just a myth. “The exact amount of fluid intake will vary based on individual factors such as body size and activity level,” says Collman. Scruggs adds that some people will need more than eight glasses depending on these factors.

So how can you figure out how much you should be drinking? “A good rule of thumb is to drink enough water so that your urine is constantly very light yellow, almost clear,” says Brantner. Scruggs suggests front-loading your water intake to avoid middle-of-the-night trips to the bathroom—because that can hinder your sleep just as much as dehydration. “In general, I’d recommend not drinking much water within two hours of bedtime,” says Brantner. “That doesn’t mean you can’t have a sip or two here or there—this may be different for different people, so it will require some trial and error.”

Here are more tips to help you increase your water intake and ensure you’re keeping properly hydrated.

Stick to drinking water that’s filtered. “Many people drink straight from the tap in order to drink enough water,” says Brantner. “However, many cities across the U.S. actually have water with unsafe lead levels.” Even in cities with clean water, pipes in old homes can cause contamination, adds Brantner. He advises sticking to filtered water. Try a filtered water pitcher, like this one from Brita.

Use your water bottle to keep track of how much you’re drinking. If you’re a visual person, Rothenberg recommends investing in a water bottle with lines to tell you how much you need to drink by a certain time of day. UnCommon Goods makes a motivational water bottle to help you meet your hydration goals.

Set reminders. Your phone can help you remember to continue drinking water throughout the day. Rothenberg likes the MyWater app, which has a calculator to help you figure out how much H2O you need daily and allows you to set up push notifications to nudge you to refill your water bottle.

Prevent boredom. Let’s face it—plain ol’ water isn’t exactly the most exciting beverage. You can jazz things up by adding chunks of fruits, vegetables, or even herbs like basil, says Rothenberg. Fan of bubbly drinks? Steer clear of sugary soda (sugar will disrupt your sleep) and reach for sparkling water, which is just as hydrating as regular water, says Rothenberg. Eating fruits and veggies with a high water content, like watermelon, strawberry, and cucumber, can also make getting enough water easier. Even soups and coffee count, says Scruggs—but they shouldn’t replace your water intake completely, so continue drinking water throughout the day.

And while we’re on the topic of drinking, here’s how alcohol messes with your sleep.

Christina Heiser is the content manager at Saatva. She has held previous positions at Everyday Health, Women's Health, and L'Oréal. When she's not working, you can find Christina checking out the latest boutique fitness classes in New York City, cheering on her college basketball team (go Red Storm!), and trying new beauty and wellness trends.