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Drink more water during the work day for cognitive performance


Water constitutes about 60% of the human body and about 75% of our brain, just a 1-2% drop in hydration can impair physical and cognitive performance.  

It is vital for numerous physiological processes:

Temperature Regulation: Water aids in dissipating heat through sweating and respiration, maintaining optimal body temperature.

Joint Lubrication: Synovial fluid, which cushions joints, relies heavily on water content to function effectively.

Nutrient Transportation: Water facilitates the transport of nutrients and oxygen to cells and the removal of waste products.

Digestive Health: Adequate hydration ensures smooth digestion and helps prevent constipation.

Skin health, kidney health... basically every cell in our body relies on water.


What about your brain? 

When you're sitting at your desk grappling the problem of the day, hydration plays a key role in how you perform. 

1.  Your brain is around 75% water
Hydration supports every key function - neural signals, mood regulation, memory, focus, and attention. When water levels drop, these processes slow down or become impaired. Cognizin

2.  Cognitive performance dips early
Losing just 2% of your hydration impairs:
  • Short-term memory and attention
  • Reaction time and processing speed
  • Overall mental resilience
This holds true across ages - from young adults to the elderly. PMC+1Health+1PubMedOur Mental HealthWikipedia+3Our Mental Health+3PubMed+3

3.  Moods suffer and fatigue rises
Dehydration increases feelings of fatigue, brain fog, irritability, headaches, and dizziness. Even after drinking water, full mental clarity doesn’t always bounce back immediately - especially if dehydration was prolonged. Our Mental Health+2News-Medical+2Wikipedia+2

4.  Blood flow and cognition
Insufficient fluids reduce cerebral blood flow. In one study, dehydration disrupted the brain’s ability to respond to stimuli, affecting decision-making and even increasing stroke risk in vulnerable people. Reddit+15News-Medical+15PubMed+15PMC

For older adults, better hydration correlates with improved attention and processing speed. A study on women over 65 found better hydration linked to sharp cognitive scores. HealthEatingWell

In one experiment, students who drank water before testing had reaction times up to 14% faster than those who didn’t. PubMed+14SELF+14Reddit+14

 How to keep hydrated

Water is the go-to energy booster, outperforming sugary or caffeinated drinks.  If plain water doesn't excite you, try adding lemon, cucumber or mint. I wouldn't recommend any carbonated drinks on a daily basis (other than mineral water), and that includes zero sugar drinks, because of the additives. Lucozade contains 10 risky additives, Coca cola zero sugar contains 7 risky additives, 4 of which are considered high risk to health Yuka. Personally, I might drink a regular coke after a four hours on a tennis court, but even then I would prefer a lime and soda (to replace sodium loss).

Interestingly, there are several studies which show that milk is better than water post intense exercise! The effectiveness of milk in rehydration is attributed to its unique composition, which includes carbohydrates, high-quality proteins, electrolytes like sodium and potassium, and a high water content.

But during the work day, herbal teas and water are my go-to.  Herbal teas are better than regular tea, as they are caffeine-free.  If you haven't had herbal tea for a while, you'll be surprised at the huge range available now.  I used to think that they smelt divine, but were tasteless! Currently, I love hibiscus, rose and sweet berries tea, by Good Earth, and the Twinings range including Glow and Balance. Regular tea contains less caffeine than coffee, but if you only drink regular tea all day it can be a diuretic, and dehydrating.

Keep a glass/bottle on your desk as a visual reminder and sip throughout the day.

  • European guidelines say you should aim to drink 2L for men and 1.6L for women daily. I've also seen guidelines that say you should drink more than that.  It depends on what you've been doing; intense physical exercise will demand much more, particularly in hot weather.   And remember your brain is around 75% water, so if you're problem solving at work all day, you will need it too.  Don't wait til you've got a headache to get a glass of water! 

  • Drink consistently - Thirst is not always a reliable signal (especially in older adults). Real SimpleVerywell Health

  • Monitor urine colour -pale yellow = good, dark = hydrate more. iCliniq+1Our Mental Health+1

  • Sip throughout the day. iCliniqReddit

  • Include water-rich foods like cucumber, melon, oranges, and leafy vegetables. iCliniqEatingWell

✅ Final Takeaway

Hydration is the simplest, most affordable way to boost your mental clarity, focus, energy, and emotional resilience. When your hydration dips - even slightly - your brain slows. 

So whether you're tackling a big project, prepping for a test, or simply managing a busy day - drink up. Your brain will thank you 💧


 


Stephanie James, Founder of refreshercise.com 

Pilates instructor & Sports Massage Therapist (Stott Pilates and Sports Performance Ltd) for over 25 years.


Header Photo by @Pixabay

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