Dehydration and Anxiety: How to Boost Your Mood with Water

One of the first signs of dehydration is brain fog—being unable to concentrate and having difficulty remembering things. It makes sense that it would affect your cognitive abilities. After all, 73 percent of your brain is water. But can not drinking enough water wreck your mood as well? According to both science and your sixth-grade gym teacher: yes.

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The science on dehydration and anxiety

Not drinking enough water or being dehydrated may make you feel depressed and anxious. This is true even when controlling for other variables that may influence mood, according to a 2018 study published in the World Journal of Psychiatry. Researchers questioned 3,327 adults about their water intake and then had them rate their mood on a depression and anxiety scale. They found that the people who drank two cups or less of plain water per day reported significantly higher levels of depression than people who drank five cups or more each day. Even people in the middle, who drank three to four cups per day, rated their moods as better than the dehydrated group.

Water and mood are so connected that even very mild dehydration—losing just 1 percent of your body’s water—can make you feel depressed, according to an earlier study published in The Journal of Nutrition. The researchers had 25 healthy young women do the same workout on three separate days. On the first day, they did a “moderate” sweaty workout and didn’t replace their sweat loss by drinking water, allowing them to become mildly dehydrated. In the second workout, they not only sweated out water but were also given a diuretic, a drug to draw extra water out of their system, making them quite dehydrated. The third workout they performed fully hydrated.

After each workout, the women answered questions about their mood and cognition. When they were dehydrated, they reported “significant adverse effects” on their mood—during the workout, after it, and when resting. They felt more depressed when dehydrated and reported other negative feelings, perceiving the workout to be harder than it was, getting frustrated, and wanting to give up.

(Related: How Rumination and Obsessive Thoughts Are Linked to Anxiety and Depression)

Your brain and water

These findings are not surprising, as the brain cannot function properly in states of dehydration, says David A. Merrill, MD, psychiatrist and director of the Pacific Neuroscience Institute’s Pacific Brain Health Center at Providence Saint John’s Health Center in Santa Monica, California. The effects start from even a small amount of dehydration and can range from subtle to severe. To understand why, first you have to understand why water is so important to your brain.

The brain doesn’t “use” water to function, but it is affected by changes in your overall blood volume. Your blood is mostly water, so when you become dehydrated, the amount of blood circulating in your body is reduced. It is this reduced supply of blood that affects brain function, says Xuan Kang, MD, a neurologist with UCHealth Neurology Clinic and assistant professor of neurology at University of Colorado Medicine.

Dehydration’s effect on the brain manifests in three ways:

(Related: Does Coffee Dehydrate You?)

Concentrated electrolytes

Your body and brain run on a fine-tuned system regulated by nutrients, and dehydration throws that balance off. When nutrients like salt get too concentrated in your blood, you can experience “altered mental states,” says Dr. Kang. If dehydration continues, it will cause seizures.

Less blood to the brain

Your blood transports glucose to your brain as a source of energy. When your brain doesn’t get enough blood, it’s not getting adequate fuel. That can lead to brain dysfunction, says Dr. Kang. This shows up as cognitive impairments—it feels harder to think—and mood disturbances.

Shrinking brain tissue

A little dehydration is not a huge deal, and your body will be able to regulate itself. But severe and/or chronic dehydration can actually decrease the size of your brain, says Dr. Kang. Reduced brain volume is linked to mood disorders, according to a study published in JAMA Psychiatry.

The mind-body connection

The physiology explains just part of the link between mood and hydration levels. You also need to consider how the physical impairments of dehydration impact mood, says Kristin Orlowski, a licensed psychologist with UCHealth Family Medicine in Littleton, Colorado. “The mind-body connection is significant, so if dehydration stresses the body, then it can also have a negative effect on a person’s behavioral health functioning,” she explains.

Dehydration can worsen short-term memory, perception of task difficulty, alertness, and working memory, all of which can cause you to feel worse, she says. That, in turn, increases depression and anxiety. Essentially, dehydration causes you to do poorly, which then causes you to feel poorly as well. These negative effects can be compounded for people who are chronically dehydrated, says Orlowski. For instance, if chronic dehydration has worsened other physical health conditions, or if it’s caused you to miss out on pleasurable and meaningful activities, it could indirectly lead to longer-term mood disorders, like depression, she explains.

(Related: Walking This Number of Minutes Will Boost Your Mood)

Mental symptoms of dehydration

You may feel the mental effects of dehydration before you feel the physical ones, although they can be subtle, says Dr. Merrill, a professor emeritus of psychiatry at the University of California-Berkeley. It’s not uncommon for people to feel their mood and productivity nosedive in the middle of the day. Often they don’t even know why. It’s only later, after drinking water and feeling clarity return, that they make the connection.

Here are some of the mental symptoms of dehydration to look out for:

• Confusion
• A feeling of mental slowness
• Fatigue
• Headache
• Inability to concentrate
• Ruminating
• Unexplained sadness
• Anxious thoughts
• Frustration or having a “short fuse”

There are other possible explanations for these symptoms, but if you haven’t had a big drink of water, guzzling a glass is the first thing you should try. It’s a quick and often a nearly immediate fix.

(Related: 9 Hydrating Foods to Maximize Your Water Intake)

How to boost your mood with water

This is one health issue that is easily remedied: drink more water and stay hydrated. That may be easier said than done, considering how easy it is to forget to drink during a busy day. In addition to water, you can also eat more hydrating foods, like watermelon, to make sure you’re body receives enough fluids. To boost hydration, start by focusing on the positive, like these surprising benefits of drinking more water. Next, try our experts’ suggestions for ways you can make drinking water a healthy habit:

Give yourself visual reminders

Remembering to drink is half the battle, so give yourself visual cues. One way is to place a brightly colored water bottle on your desk and take a sip every time you notice it.

Schedule drink breaks

Set an alarm for every two hours on your phone to remind you to drink a glass of water. While you’re at it, take a quick five-minute stretch, or walk around—exercise is also a proven mood-booster.

Add some flavour

While plain water is the healthiest option, many people find it boring and bland. To inspire yourself to drink more, try adding a squeeze of lemon or lime, drinking an unsweetened flavored water, or down a sparkling variety.

Log it

A proven way to build healthy habits is to hold yourself accountable. One way to do that: keep track of your intake. You could log each glass of water into your fitness app or on your smartwatch, make check marks on a calendar, text a friend, try a habit-tracking app, or move rubber bands up your water bottle with each drink.

Make it part of a healthy lifestyle

Hydration is just one part of managing depression and anxiety. To really boost your mental health, make sure you’re also eating a healthy diet, getting enough sleep, exercising daily, and reducing your stress. If you are still struggling with depression or anxiety, talk to your doctor or a therapist for more help, says Dr. Merrill.

Now that you know about dehydration and anxiety, this is what you should know about drinking water left out overnight.