Is it time for a drink? - THINKERS Notebook

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Is it time for a drink?

When you're struggling to think clearly and productively, what do you typically assume is the issue?
  • Lack of sleep?
  • Hunger?
  • Anxiety?
  • Clutter?
  • Overwhelm?
  • Noise?
  • Notifications?

It could be any of those things. It could be all of things. It could be none of those things.

No one single factor is the difference between us being a superthinker or a dolt. 

But one contributor to mild cognitive impairment is so easy to take granted that you might not even consider it ... 

Are you drinking enough water?

Because it turns out your hydration level isn't just important when it comes to physical exertion; it can make a big difference for mental exertion too.

As explained in this meta analysis published in the British Journal of Nutrition, there is consistent evidence for short-term memory and perceptual abilities being affected by dehydration. The evidence is a bit more mixed for dehydration affecting cognitive functions such as working memory and executive function.

There is also evidence that dehydration affects mood, even if performance on cognitive tests does not suffer. Dehydrated subjects were more likely to report mood states such as ‘less alert’, ‘difficulty in concentrating’, ‘fatigue’ and ‘tension'.

It makes sense.

The human brain and body are made up mostly of water. We shouldn't be surprised to learn that a deficit of such an important ingredient causes myriad issues in how we function. 

The question, then, is how much water do we need to function -- and specifically for our purposes: think -- at peak levels?

But the answer is not "as much as you can possibly guzzle."

Because while dehydration is bad, the less-common-but-still-serious overhydration can carry its own deleterious effects.

So like most things in life, balance is good. There is a sweet spot to try to stay within that will lead to optimal hydration and, if other factors are also in line, optimal performance. 

There is, however, no one-size-fits-all answer for how much water you should drink each day.

The amount of water you need to drink will be based on many factors: 

  • Height
  • Weight
  • Age
  • Activity level
  • Diet
  • Even the weather where you live

Which is why the best advice on how much water you need to drink usually involves some variation of the following:
  • If you feel thirsty, drink some water. (Your body usually knows.)
  • If you feel hungry and it's not mealtime, stop to consider if you're actually thirsty. Thirst can sometimes masquerade as hunger.
  • If your urine is noticeably yellow to dark yellow, you probably need to drink more water.

For a more detailed analysis of how to assess how much water you need, read these guidelines from the Mayo Clinic.

Personally, I have been very intentional about drinking more water each day. I use the Hidrate Spark water bottle and app, which I highly recommend.

The Hidrate Spark tracks your water consumption over time and allows you to set goals, which I have found to be very helpful in establishing and keeping a consistent habit of drinking enough water each day. (To be clear: we are not affiliated with Hidrate in any way, so we get no kickbacks or commissions if you decide to get a bottle. I just like it, so wanted to pass along.)

One habit I have found very useful is to not have my first cup of coffee until I've consumed a full bottle of water. I love my morning coffee, so this motivates me to drink some water at a time of day when my body consistently needs it.

After 6-8 hours of ingesting no liquids while we sleep, our bodies often crave the hydration boost when we wake up. And if you find that you are consistently waking up noticeably parched, you should dig deeper to figure out the reasons why.

So tell me ...

What is your plan for ensuring that you are getting enough fluids each day? Hit reply on this email and let me know.

Below, you will find three articles that go into more detail about the impact that drinking water has on our cognitive abilities. 

But first, we have an upcoming virtual happy hour to invite you to, as well as a new poll question for you to answer.

This Week in the THINKERS Workshop


It's time for virtual happy hour #3, and this one is going to be on a different day.

We are switching things up a bit to see if a day besides Friday might work for some folks who haven't been able to attend yet. 

So if you're available, please join us for a fun, relaxed virtual happy hour on Tuesday, May 5th at 6:00 p.m. ET.

Click here for details, to RSVP, and to get the Zoom link.

Also, I threw out another fun discussion question earlier this week:

What is your superpower?

You can see how fellow Workshop members replied and add your reply as well. 


Now on to this week's links ...

Dehydration can cause cognitive decline at all ages


We often hear the adage about the importance of drinking eight glasses of water a day to keep our bodies healthy, but how about our brains? The adult human body contains around 60% water. All the cells in the body, including our brain cells, depend on this water to carry out essential functions. Therefore, if water levels are too low, our brain cells cannot function properly, leading to cognitive problems.

The brains of dehydrated adults show signs of increased neuronal activation when performing cognitively engaging tasks, indicating that their brains are working harder than normal to complete the task. In healthy young adults, this additional effort typically manifests as fatigue and changes in mood, but in populations with less cognitive reserve, such as the elderly, this can lead to a decline in cognitive performance. 

Read: Can Dehydration Impair Cognitive Function? (Cognitive Vitality)

Don't take access to water for granted


On most mornings, one of the first stops through my waking-up routine is the kitchen cupboard, where I keep my cups and other drinking vessels. Even if I'm not particularly thirsty, as a student of the brain, I'm convinced of the value of drinking enough water.

Of all the tricks I've learned for keeping my mind sharp, from getting enough sleep to doing crossword puzzles, staying hydrated may be the one I follow most closely, partly because it's so easy to get a drink whenever I'm thirsty. This is a convenience to be grateful for.

Read: Why Your Brain Needs Water (Psychology Today)

Fluid loss equals impaired brain function 


Your brain is strongly influenced by hydration status.

Studies show that even mild dehydration (1-3% of body weight) can impair many aspects of brain function.

In a study of young women, fluid loss of 1.36% after exercise impaired both mood and concentration, and increased the frequency of headaches.

Another similar study, this time in young men, showed that fluid loss of 1.59% was detrimental to working memory and increased feelings of anxiety and fatigue.

A 1-3% fluid loss equals about 1.5-4.5 lbs (0.5-2 kg) of body weight loss for a 150 lbs (68 kg) person. This can easily occur through normal daily activities, let alone during exercise or high heat.

Many other studies, ranging from children to the elderly, have shown that mild dehydration can impair mood, memory and brain performance

Quote of the week

“If there is magic on this planet, it is contained in water.” 

-- Loren Eiseley