How Dehydration Affects Your Child's Brain Function and Mood

Toddler boy drinking a glass of water

Silvia Jansen / Getty Images

It may seem strange that something as simple as drinking enough water can affect your child's brain. But research shows that hydration status, brain function, and mood are closely linked.

Even mild dehydration can cause headaches, low energy levels, and changes in mood and mental status, which is especially important for children who are expected to concentrate all day at school. The good news is that there are plenty of ways you can help your child get enough to drink each day.

Why Kids Become Dehydrated

Children are particularly vulnerable to dehydration due to their high activity level and high ratio of body surface area to mass (meaning that when a child sweats, they lose more of their body's water than an adult does). Also, young children often rely on adults to monitor their intake and provide a drink when needed.

Research shows that kids tend to underestimate how much and how often they need to drink. Even in situations where water is readily available, children may not realize they should be drinking throughout the day, or they may forget to do so.

Psychological Effects of Dehydration

While the physical effects of dehydration have been studied for decades, the impact of dehydration on mental status is a relatively new area of research. Studies in children are newer still, but they tend to confirm the results of studies in adults.

Research shows that even low levels of dehydration can affect a child's mood, energy level, and ability to concentrate. A 2011 review of studies on 7- to 9-year-olds in a school setting found that poor hydration was correlated with a variety of physical and mental complaints, including:

A 2015 review of 21 studies reported that in every one, mood was negatively impacted by dehydration.

Research conducted at the University of Connecticut found that even mild dehydration in young adults affected their mood, leading to increased feelings of tension and anxiety. Study subjects also experienced headaches, fatigue, and difficulty concentrating.

“Nearly every function of the body is pegged to the efficient flow of water through our system," says Barry McDonagh, author of Dare: The New Way to End Anxiety and Stop Panic Attacks Fast. "Water transports hormones, chemical messengers, and nutrients to vital organs of the body. When we don’t keep our bodies well hydrated, they may react with a variety of signals… some of which are symptoms of anxiety.”

Researchers have not yet determined the point at which dehydration begins to affect brain function. And they may not find an answer anytime soon; the body's response to water intake and other factors affecting hydration (such as ambient temperature, perspiration, and physical activity level) appears to be highly individualized.

What does all this mean for your child? Drinking enough water during the day—especially while at school—can have a significant impact on how well they learn and behave in class.

Physical Signs of Dehydration

By the time your child feels thirsty or asks for a drink, their body may already be dehydrated. Experts say that the thirst mechanism is not triggered until hydration levels are already significantly lower than needed for ideal functioning. This is why kids should drink water throughout the day, before thirst develops.

Watch for these important signs of mild to moderate dehydration in your child:

  • Dry, cool skin
  • Dry or sticky mouth
  • Fatigue or dizziness in an older child
  • Few or no tears when crying
  • Headache
  • Thirst
  • Urine that is darker than pale yellow

Severe dehydration may be indicated by one or more of the following:

  • Confusion or irritability
  • Lack of urine in a 12-hour period
  • Loss of consciousness
  • Rapid breathing or heartbeat
  • Sunken eyes
  • Urine that is dark yellow and/or has a strong odor

Call your doctor or 911 if you observe symptoms of severe dehydration in your child. They may need intravenous (IV) fluids for rapid rehydration.

Daily Hydration Recommendations

This chart provided by the Institute of Medicine outlines recommendations for daily water intake for generally healthy children living in temperate climates. Keep in mind that these guidelines are for total water, which includes water from all sources: drinking water, other beverages, and foods such as fruits and vegetables.

Daily Fluid Recommendations for Children

Age Range
(Years)

Gender

Total Water
(Cups/Day)

4 to 8

Girls and Boys

5

9 to 13

Girls

7

9 to 13

Boys

8

14 to 18

Girls

8

14 to 18

Boys

11

Kids may need to drink more water in certain situations. Before, during, and after any physical activity, they should drink 3 to 8 ounces of water every 15 to 20 minutes (teens need 34 to 50 ounces).

Plain water is the best way for kids to stay hydrated. The American Academy of Pediatrics advises parents that drinks containing artificial sweeteners, caffeine, and/or sugar should be avoided. If you aren't sure if a beverage contains one of those ingredients, check the nutrition label or choose water instead.

Sports drinks contain electrolytes and carbohydrates to replace those lost during prolonged high-intensity exercise. For most kids, water is the best choice even on a hot day or at sports practice.

Help Kids Stay Hydrated

Although dehydration can cause a variety of problems in children, it's usually a preventable condition. When kids drink the appropriate amount of water throughout the day, they can minimize or avoid side effects caused by dehydration.

Come up with a simple schedule to help your kids remember to drink regularly. For instance, they can get a drink of water every time they pass the sink or fridge at home, or every time they change classes at school.

You can also teach your kids to notice the color of their urine as an easy way to check their hydration status. Any color darker than pale yellow indicates that they are dehydrated and need to be drinking more water.

If your child's school does not allow students to have a water bottle on their desk, consider talking to the administration to see if that policy could be changed. Studies show that kids drink more at school when they have a water bottle within arm's reach.

Make Water More Fun

Although plain water is the best choice for staying hydrated, the availability of sweetened and flavored drinks means that kids don't always reach for water first. To increase their water intake, try these strategies:

  • Add flavor and color. Infuse water with flavor by adding berries, watermelon, pineapple, cucumbers, lemons, or limes. Try using frozen fruit in place of ice cubes, or freezing ice cubes with berries in them.
  • Be a good role model. Carry your own water bottle with you on the go, and drink lots of water at home. The more your child sees you drinking water, the more likely they will be to ask for it.
  • Factor in friends. Buy special cups or water bottles with your child’s favorite characters.
  • Make it accessible. Bring water bottles wherever you go. For little ones, leave a cup of water in a spot that your child can easily reach when they want a drink.
  • Try some fizz. Offer unsweetened, caffeine-free carbonated water to older children. They can add fresh fruit for a bit of flavor.
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