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Should You Be Drinking Water Before Bed?

Your brain may be tricking you into drinking water before bed (which may wake you up at night). Here’s how to hydrate and still meet your sleep need.
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Jeff Kahn, M.S., Rise Science Co-Founder
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Bedside table with water jug and glass: should you drink water before bed

Almost every time you're about to climb into bed, you're besieged by a deep wave of thirst. You can't help but quench your dry mouth with a glass of water before sliding in between the sheets. Yet, you've also woken up in the middle of the night more often than you'd like to relieve a full bladder (otherwise known as nocturia). So, the dilemma is, should you be drinking water before bed or not?

We all know that adequate fluid intake is needed to keep your internal organs at their healthiest. Not drinking enough water leads to a slew of health problems such as constipation and urinary tract infections. But, chugging down water just before you sleep is probably not the wisest move. Knowing the right times for fluid consumption is key to ensuring you get the sleep you need while optimizing your health and wellness.

In this article, you'll learn the biological mechanism behind pre-bedtime thirst and why you don't necessarily have to indulge in it. You will also discover the cons of drinking water before bed and the right way of hydrating yourself without risking sleep deprivation.

The Brain Tricks You Into Feeling Thirsty Right Before Sleep

The reason why you feel thirsty right before bedtime is due to your biological clock located in the suprachiasmatic nucleus (SCN) of your brain. Roughly 20% of the SCN is made up of arginine vasopressin (AVP) producing neurons. AVP is a type of antidiuretic hormone produced in the hypothalamus. It regulates your body's fluid balance by reducing the amount of pee your body produces as and when needed, such as during nighttime sleep.

Aside from its water-retaining capabilities, vasopressin also prompts your body to drink more fluids. Scientific literature explains that AVP neurons are more active in the few hours preceding sleep, resulting in anticipatory thirst before you drift off.

Using rat models, McGill University researchers pointed out "a surge in water intake during the last two hours before sleep." The study notes that this thirst mechanism isn't triggered by dehydration. In other words, you don't actually need to hydrate before bed (provided you've already met your daily fluid intake). Rather, this anticipatory thirst acts as a preemptive strike against potential water loss during nighttime sleep.

Plus, your body naturally protects itself against dehydration while sleeping, further eliminating the need for drinking water before bed. It’s all thanks to your hardworking biological clock that's constantly ticking away, even after you've dozed off.

Sleep Deprivation Is Far Worse Than Mild Thirstiness

Drinking water before bed: man sitting on his bed, covering his face

So, should you drink water before bed? While it's important to drink enough water during the day, too much water too close to bedtime is the reason why you're awakened by your full bladder in the middle of the night  — and you’re burdened with increased sleep fragmentation. After visiting the restroom and lying down in bed again, many of us often take some time to re-enter dreamland. In which case, the prolonged sleep latency further cuts into your sleep duration.

Understandably, you wake up the next day feeling more tired than usual due to not meeting your sleep need (the genetically determined amount of sleep your body needs). Consequently, you rack up acute sleep debt — the amount of sleep you've missed out on in the past 14 days relative to your sleep need.

If you keep this up over time, the routine middle-of-the-night awakenings may drown you in chronic sleep deprivation. As you can see, downing a large amount of water before bed leads to a lack of sleep, be it in the short or long term.

Science warns that nocturia-induced sleep loss brings about several downsides that depreciate your overall well-being:

  • Another Swedish study found that nocturia was associated with increased sleep disorders and amplified daytime fatigue.
  • A 2002 study highlighted that the greater the frequency of nocturia, the greater the risk of poor sleep, heart disease, diabetes, and stroke.
  • A Boston area community health survey discovered that waking up to use the bathroom during the night is closely associated with poorer mental health in the form of increased depression.

So unless you're at risk of extreme dehydration (which is a rarity to begin with), gulping down a few ounces of water pre-bedtime only sets you up for more frequent nighttime awakenings.

In addition, more research highlights the close relationship between short sleep (roughly six hours) and the increased likelihood of dehydration. Skipping out on a few hours of sleep means you're more likely to miss the AVP surge that happens during your sleep cycle. This diminishes your body's ability to withhold water, putting you at greater risk of dehydration. On top of that, you will probably wake up more often than usual to empty your bladder. In other words, it's a vicious cycle of sleep loss and dehydration feeding into each other.

Instead, skip drinking water before bed and prioritize getting enough sleep to help you feel and function at your best (or as close to it as possible) during the day.

Hydrate at the Right Times Throughout the Day

Drinking water before bed: woman drinking a glass of water

Instead of drinking water before bed, the best thing you can do is spread your fluid intake throughout the day. Although there are no specific guidelines on how much water you should be drinking every day — the Centers for Disease Control and Prevention (CDC) recommends letting your thirst dictate your daily fluid intake — a good rule of thumb is eight 8-ounce glasses, give or take.

Concentrate on drinking as much water as you can from the moment you wake up till the late afternoon. One side benefit of upping your morning water intake is that it could be an effective weight-loss strategy. The Journal of Physiology and Behavior indicated that normal-weight participants who drank three 500ml bottles throughout the morning were less hungry at lunch. (Do note that this effect wasn't observed in participants with obesity.)

Then, start slowing down your fluid intake from the late afternoon or early evening, especially after dinnertime. Make sure you stop drinking water at least two hours before your target bedtime. One study shows that a short fluid intake-to-bedtime window of one hour wasn't enough for people with nocturia. So, experiment to figure out the buffer duration that works best for you.

Here are two more tips to stay adequately hydrated throughout the day and night:

  • Cut down on salty foods, especially as the day progresses. Too much dietary salt hikes up your risk of dehydration, making you feel thirstier than usual.
  • Ensure your sleep environment is between 65-68 degrees to keep your body temperature cool enough. This way, you're less likely to sweat while sleeping and lose more moisture than necessary. (Check out our Sleep Guide for other bedroom-perfecting sleep techniques.)

Keep in mind that what you drink at night matters as well. For example, alcoholic beverages are well-known diuretics that increase the likelihood of nocturia. Similarly, hot cocoa and chocolate milk usually contain caffeine, which not only makes it harder for you to fall asleep but also acts as a bladder stimulant. 

Use the RISE app to know when you should cut off caffeine and alcohol consumption based on your unique chronobiology. All you need to do is add the “Avoid Late Alcohol” and “Limit Caffeine” habits to your Energy Schedule for timely in-app reminders.

So, what should you drink instead? We recommend cold water in lieu of warm water. Because cold water inhibits the neurons that promote fluid intake, research favors cold fluids as a more effective thirst-quencher (which may help tone down pre-bedtime anticipatory thirst). That being said, if you're dealing with a head cold or stuffy nose, drinking hot water may help relieve some of the flu symptoms so you can fall asleep more easily.

Think Twice About Drinking Water Before Bed

RISE app screenshot showing your melatonin window which can tell you when to cutoff fluid consumption.
The RISE app shows your daily Melatonin Window, which can help you determine when to cutoff your pre-bedtime fluid consumption.

The next time you're tempted to give in to the urge of drinking water before bed, think twice. What may be a temporary moment of satisfaction will likely give birth to a night of disrupted sleep and next-day sluggishness.

If you've been diligently hydrating yourself during the earlier part of the day (keep a water bottle nearby as a visual cue), there won't be any need for drinking water before bed. Also, if you're worried about not being sufficiently hydrated while you snooze, science has shown that as long as you've met your fluid intake during the day, your circadian rhythm will naturally take care of your body's hydration levels throughout the night.

So, the bottom line is, prioritize and protect your sleep need by drinking at the right times during the day. Stop all fluid consumption at least two hours before your target bedtime to lower the likelihood of nocturia.

The RISE app lets you know when to stop drinking water before bed. It shows your daily Melatonin Window on the Energy Schedule, the prime time for sleep due to the peak levels of melatonin (a sleep-promoting hormone) surging through your body. Cutting off your fluid intake at least two hours before your Melatonin Window gives you the best chance of sleeping through the night to meet your sleep need. You're more likely to wake up feeling your best and ready to take on the day.

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