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Tasks Your Brain Performs Poorly When Dehydrated

Tasks Your Brain Performs Poorly When Dehydrated

Tasks Your Brain Performs Poorly When Dehydrated

Medical experts recommend that we drink eight glasses of water a day. That may sound like a lot of water, but since 70 to 80 per cent of our bodies consist of water, it should not be surprising that our bodies need plenty of it to remain hydrated. As a result, whether you are thirsty or not, you had better drink the required eight glasses a day, or even more depending on how active you are, to satisfy your body's needs.

Your brain is especially sensitive to water, or more precisely, to the absence of water, and since your brain drives so many of your most essential functions, you should never neglect its needs.

Tasks Dehydrated Brains Do Poorly

  • Even mild dehydration have been found to reduce concentration, alertness and short-term memory in people of all ages, from children between ages 10 and 12, to young adults between ages 18 and 25, to the middle aged and elderly between ages 50 and 82. Concentration, alertness, and short term memory are precisely those skills that children require to get successfully through a school day, and that adults require to complete most of their tasks at work. Even non-office workers, like drivers and factory workers, need to concentrate well and respond properly to instructions, messages, and other information stored in short-term memory.

  • Mild to moderate dehydration have been found to weaken people's performance on tasks requiring short-term memory, perceptual discrimination, arithmetic, psychomotor skills (the ability to move fast in response to a conscious decision), and visuomotor tracking, which refers to the brain's ability to coordinate visual perception and the body's movement, such as you do when running to catch or hit a ball. Interestingly, these effects at low levels of dehydration (2.8 per cent dehydrated) were not consistently found in all people, which seems to suggest that some people's brains are better at compensating for a slight lack of water. Since so many people drink almost no water, or drink only when they are thirsty, we are usually dehydrated at a higher level than that. If these studies are taken seriously, we can see that it is not only strictly mental operations that are affected, but also functions where the brain is supposed to coordinate the body’s movements. The ability to do this successfully is not important only to sportspersons and dancers, but also to typists, childminders, chefs, broadcasters, laboratory workers, chauffeurs, artists, construction workers, and anyone else who moves around.

  • People who are old or seriously mentally ill display higher levels of delirium and confusion when they are dehydrated. This kind of confusion is often interpreted as dementia. This is worrying, especially because these groups are often institutionalised or physically impaired and unable to get their own water. If you take care of an elderly relative, pay special attention to the water and you may see an improvement in mental functioning.

  • People who drink too little water report having headaches and having longer migraine episodes. Water can relieve this within the first hour after drinking. The brain is both surrounded by and filled with water, so the stress it undergoes when dehydrated is understandable.

  • The brains of dehydrated people also fail to regulate mood, which is why they report feeling tired, listless, and down. This effect was found in both men and women. Another study verified that moderately dehydrated people experienced fatigue, sleepiness, and listlessness, and further discovered that, at a higher level of dehydration, people felt less calm, more anxious, and less happy. These findings on mood are rather alarming, as these symptoms closely resemble those that depressed people experience. In fact, researchers have reached the same findings on mood for people who habitually drink little, as opposed to those who are deprived of water on a single occasion. If you feel tired and down, it may be because you drink too little water.

Ideal Hydration Techniques

  • We all know we should drink approximately eight glasses of water per day. Those who exercise or work in hot factories or outside should drink substantially more than that, because they lose a lot more moisture through perspiration than office workers do. It is important not to wait until you are thirsty before you drink, as thirst is a sign that your body is already dehydrated. You want to drink before the thirst kicks in, otherwise you will compromise your performance for up to an hour while your body absorbs the water you drink to quench thirst and combat dehydration.

  • The best practice is to carry a bottle of water around with you in a handbag or backpack. It enables you to drink some water at least once an hour.

  • Be particular about the type of water you drink. It does not have to be store-bought bottled water. In fact, bottled water is sometimes simply tap water that contains all the same fluoride, heavy metals, and hormones as your tap water at home. These often include arsenic, lead, and pesticides, so do not dismiss this concern too lightly. Moreover, bottled water can also contain acid minerals or be contaminated with phthalates that leak from the plastic bottles in which it is stored for an extended period while sitting on supermarket shelves. Phthalates are known to disrupt the production and functioning of some of our hormones.

  • If you filter your own tap water and pour it into bottles that you drink up daily, you will drink it before phthalates can leach into it. Moreover, you will know exactly what the water contains, especially if you buy a filter whose filtering properties have been scientifically tested.
  • Water filtered through a scientifically tested alkaline filter is free of the health-compromising contaminants found in tap water, it is free of acid minerals, and it is high in good alkaline minerals like potassium, calcium, and magnesium. These are the minerals that help to maintain your bone and muscle density and strength.

  • Alkaline water makes it easier for your body to regulate its own pH to the required level of 7.4 without having to borrow alkaline minerals from your bones and muscles. Alkaline water is also an effective free radical scavenger that prevents oxidative damage to cells.

  • If you cannot afford a water filter, squeeze a tiny bit of lemon juice into each glass of water you drink. It will not remove the contaminants found in tap water, but it will raise the alkalinity of the water.


As you can see from all the studies quoted above, your brain genuinely struggles without water. Your grandmother was not confused when she recommended eight glasses of water a day. Your brain needs it, and will reward you handsomely for it by improving your concentration, alertness, short-term memory, perceptual discrimination, arithmetic, psychomotor skills, visuomotor tracking, energy, and mood positively.

If you're looking to start drinking more water, try our AHA Water Bottle which supplies you with pure alkaline water on the go.