The Effects Of Dehydration On Brain Function (Scientific Evidence)

A woman who looks tired and affected by dehydration.

With your body made up of over 60% water, it is no question that a lack of drinking water can affect how your body functions. Staying hydrated helps your body perform natural processes such as temperature regulation, waste removal, and transporting nutrients. Despite significant research into the effects of dehydration on your body, there isn’t much evidence to support the claim that dehydration affects brain function.

However, recent studies have shed some more light on how cognitive performance is affected by the amount of water that your body loses. In this article, we’ll take a closer look at how dehydration and brain function are related and provide some tips to help increase your water intake.

Scientific Facts To Support How Dehydration Affects Brain Function

A recent study conducted by researchers at Georgia Tech’s School of Biological Sciences concluded that dehydration can impair cognitive performance.

The study, which was led by Professor Melinda Millard-Stafford, found that certain aspects of cognitive performance were more affected by dehydration. Tasks that required significant focus, attention, and executive function, as well as motor coordination, were observed to be most affected.

Other aspects of cognitive performance, such as reaction time, and information processing, were not observed to be as greatly affected by dehydration. Additionally, findings from the study suggested that dehydration caused the accuracy of a given task to be more impaired than the actual reaction times of completing the task.

This suggests that when dehydrated, individuals may be more prone to making mistakes while performing activities that require a high degree of attention but are repetitive and mundane.

Examples of these types of tasks could be driving, food preparation work in a restaurant, or repeating the same task in a manufacturing plant or assembly line for an extended period.

These tasks require a high degree of attention because mistakes could result in serious injuries. However, as these activities are so repetitive and unengaging, it is hard for the mind to stay focused. This is especially true when dehydrated.

The Georgia Tech study also concluded that dehydration impaired cognitive performance was especially noticeable when an individual lost fluid that was more than 2% of their body mass. This means that after an individual lost more than 2% of their weight from sweating, their cognitive performance began to drop off significantly.

While losing 2% of your body weight to sweat can seem like quite a bit, it happens a lot more frequently than you would think. For instance, an individual who weighs 150 lbs would have to lose only 3 lbs. Water loss of that magnitude can be achieved quite easily with one hour of moderate exercise in warmer climates.

How Symptoms Of Dehydration Affect Brain Function

Cognitive functioning can be defined as multiple mental abilities, such as learning, thinking, reasoning, remembering, problem-solving, decision making, and attention. All of these functions of the brain can be significantly reduced when dehydrated, as one of the most common symptoms of mild dehydration is a headache.

Headaches can cause significant pain, uneasiness, and be a hindrance as you try to go about your daily activities. As a result of the headache you might experience when dehydrated, all cognitive functions are impeded to some degree. For example, your ability to learn, solve problems or remain engaged in conversations are all affected when you have a headache.

Other Symptoms Of Dehydration

While brain function is greatly affected by dehydration, it might hard for you to recognize that your decision making or reasoning abilities have lessened. There are more noticeable and pain-related symptoms of dehydration than the effect it has on your cognitive performance.

Other symptoms of mild dehydration can include a headache, dark color urine, feeling nauseous or faint, dizzy, dry mouth, or sticky saliva. If not treated, mild dehydration can lead to severe dehydration which could have serious consequences and requires immediate medical attention.  

How Much Water Should You Be Drinking?

Like many things in life, the amount of water you should be drinking to stay hydrated depends greatly on the individual. While healthcare professionals used to recommend eight, 8-ounce glasses of water a day, recent studies have shown there is a little more to it than a one size fits all answer.

The amount of water an individual requires can depend on many factors such as their body size, how much exercise they do, what they do for a job, their diet, and if they are exposed to warmer climates for extended periods.

Determining Factor: Body Size

Your blood consists of a large portion of water which helps to transport nutrients throughout your body. Those who are larger in size require additional water because there is more ground to cover to transport the nutrients.

Determining Factor: Diet

While a considerable amount of the fluids you receive are from the liquids you drink, the average person also gets up to 20% of the fluids they require from the foods they eat.

Diet can play a large role in hydration. Those who are eating foods with high water content won’t need to drink as much water.

Determining Factor: Exercise

Exercise is also another important factor when questioning how much water you should be drinking. While exercising, fluids are lost in the form of sweat as it helps to cool your body down. It is necessary to replenish these lost fluids during and after exercise.

Determining Factor: Occupation

Additionally, what you do for work can also play a significant role in determining how much water you should be drinking. If your job involves sitting at a desk all day, you might not need to drink as much water as someone who works a manual labor job outside in warmer climates.

The Positive Effects Of Drinking Water

In general, you should be drinking water when you feel thirsty and at regular intervals throughout the day. Keep in mind that your body loses more water when you are sick, during exercise, and when exposed to warmer climates, so drink some more water in those scenarios.

Recommended Products

Check-out the list of the products we recommend to help keep you hydrated throughout your day.

In addition to increasing your brain function and cognitive performance, there are many other ways your body benefits from drinking water.

Other functions that rely on staying hydrated include reducing joint and back pain, helping to fight acne, improving your outlook on life, increasing performance during sports, and many more.

In a recent article we wrote, Benefits of Drinking Water and Staying Hydrated, we review 20 important ways that drinking water helps the natural processes that occur within your body to perform as they were intended to.

How Can You Drink More Water To Avoid Dehydration And Improve Brain Function? (6 Tips)

Now you know the effects of dehydration on brain function, and how drinking water can minimize these and other symptoms of dehydration. But what are some tips to help you drink more water?

Everyone knows they should drink water, but many people still suffer from mild dehydration on a regular basis.

There are usually two main reasons that people don’t drink enough water. Firstly, they forget. Life is busy, and they have a full schedule and drinking water is not on their to-do list as a top priority.

Secondly, water can be plain and unexciting, many people find it boring and as a result, don’t drink it. 

Below, we provide some tips to help you drink more water throughout your day to help keep your brain and body operating effectively.

1. Purchase A Reusable Water Bottle

It is a lot easier to keep track of your water intake when you are drinking from the same water bottle each day. Sure a glass of water on your desk might help to keep you hydrated.

However, you can’t throw a glass of water in your bag to keep you hydrated in the various other scenarios throughout your day when you aren’t sitting at your desk.

Furthermore, glasses are usually small and require you to refill them often. If the water fountain is more than an arms-length away, you might be able to persuade yourself more easily that filling up your water glass can wait until later.

Purchase a water bottle that:

  • can travel with you throughout all your daily activities,
  • is larger enough that you only have to fill it up once or twice a day (reduces laziness and easier to track), and
  • can keep your water cold for extended periods

We recommend any of the top 5 best water bottles for daily use that we reviewed in a recent article. However, our favorite was the stainless steel water bottle from Hydro Flask.

It keeps contents cold for up to 24-hours, has a carry loop to attach to your bag, and fits three different lid styles (straw lid, flex cap, and flip lid) depending on the activity you are using it for. You can find the Hydro Flask water bottle on Amazon here.

2. Set Hydration Goals

Set a goal of how much water you want to drink each day to help hold yourself accountable to drink more water. You can do this by using your reusable water bottle.

An example could be to finish your water bottle before lunch-time, refill it, and have it finished again before you leave work in the evening.

Like anything in life, setting goals gives you direction and helps you to track your progress. Hydration goals should be no different.

3. Try Hydration Drinks After Exercise

While drinking water should be your first and most accessible choice for staying hydrated, there are alternatives when you are in need of an extra boost.

Oral rehydration solutions (ORS), also known as hydration drinks, are designed to help you hydrate when a significant amount of your body fluids have been depleted.

They are frequently used at the end of high-intensity sporting events such as marathons or triathlons. Other common uses are when an individual is dehydrated from being hungover, or after significant fluid loss from sickness.

In a recent article, we reviewed our top 5 picks for hydration drinks. We recommend Liquid I.V.’s hydration multiplier as it is designed to hydrate your body more efficiently and effectively than water alone.

You add one packet to 16 oz. of water and shake it up. It is available in 3 tasty flavors and it provides the same hydration relief as drinking 2 or 3 bottles of water. You can find it here on Amazon.

4. Eat Food With High Water Content

As mentioned above, a good portion of the fluids you receive is from the foods you eat. If you are tired of drinking fluids, you can boost your liquid intake by eating foods with high water content.

Many fruits and vegetables are over 80% water, some even above 90% such as rhubarb, watermelon, strawberries, as well as lettuce, celery, and cucumbers. Other foods with high water content include soups, stews, chili, and broths.

5. Set Reminder Alarms

With busy lives, you may find yourself setting reminders and alarms to prevent you from missing important meetings or events. Why not do the same to keep you on track with your hydration goals?

Set an alarm on your smartphone or smartwatch to remind you to drink water. Or put a sticky note somewhere in your line of sight that will remind you to have a drink while working.

Other alternatives could be a water bottle with time markings on it. These water bottles have markings incremented by two hours from 7AM until 9PM as a means to keep you hydrated throughout the day.

When you notice the water level is above the current time, you better get drinking. Additionally, the water bottles also have motivational quotes next to each time marking which provides some positive reinforcement to stay on track.

Furthermore, with advances in technology, water bottles with reminder alarms are now a thing. In an article we recently wrote, the water bottles reviewed provide a visual, audible, or a mix of both as a reminder for you to drink more water.

Other features of these water bottles include tracking your water intake and syncing to a smartphone app that graphs your results. 

6. Infuse Water

For those that are bored of the taste of water, consider infusing it with fruit. Fruit-infused water is a healthy alternative to sugar-filled drinks, but still provides added taste from the fruit.

Simple recipes can include you squeezing lemon or lime into your water, while more complex ones can include various fruits and herbs. If you are looking for ideas, check out seven of our favorites fruit-infused recipes.


Despite the significant studies conducted to determine the effects of dehydration on your body, there hasn’t been much evidence in regard to the effects on your brain.

However, recent studies by Georgia Tech showed that cognitive performance significantly decreased in individuals who lost more than 2% of their body weight in water. It was observed that the dehydrated individuals were more prone to making mistakes when performing repetitive tasks that were boring but required a high level of attention.

The results provide cause for concern as there could be potentially fatal consequences when completing high-risk tasks. Examples could be driving when dehydrated or the repetitive nature of operating machinery in a manufacturing plant when dehydrated.

To ensure your natural body processes maintain effective, including brain function, it is important to stay hydrated.

For any comments, questions or feedback you might have, please send us a message through our contact form.


Facts for this article are referenced from credible sources. For further information, please read the referenced articles from the following organizations:

Be sure to consult your health care professional with any medical questions. Similarly, the information found in this article should not be considered medical advice.

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