It's worth emphasizing, which they also do, that this primarily affects middle-aged to older people, and "extreme" conditions. There is no benefit to "stay hydrated" beyond not being dehydrated and in fact it can be somewhat harmful to drink too much water. If you are middle aged or above, if you are in an excessively warm or cold climate, if you do great physical exertion etc. you may need to be mindful of your water intake and make sure you drink enough (and not too much), but generally your body will regulate this through the sense of thirst. Obviously being too focused on your work can also mean you neglect said thirst, so frequent breaks are healthy for several reasons.
One of the best moves wrt nutrition, fitness, and productivity I've made the last couple years is adding electrolytes to my supplement stack.

I've always been deliberate about having sufficient water intake, but supplementing electrolytes on top of that made a small, but noticeable, difference. I take a small amount by pill w/each meal (along w/a multi-vitamin, etc.), and via powder form in my water or beverage once a day. I feel more refreshed and focused while at work or at the gym, and I no longer experience muscle cramps (I never had them frequently, but being deliberate about electrolyte intake has removed them entirely).

So, while the study focused on 'hydration', it's worth remembering that doesn't comprise of water intake alone. My performance and focus on sufficient water intake, while ok, felt inferior compared to sufficient water intake + electrolyte supplementation.

Non-interventional study design. Hydration measured by osmolality.

I wonder if other factors like glucose level could affect both osmolality and cognition?

Would be much more interesting as a randomized trial (though I'm not sure what would make a good placebo intervention as a control).

This very much happens to me. What has been so odd about understanding it is that I don't detect the sustained attention problem as dehydration or thirst. I detect it as hunger or a general malaise, a need to be woken up, for which the answer can feel like- should consume caffeine. Neither food nor caffeine help.

If my system 2 is able to intercept this processing and logically hypothesize- try plain water first- after starting to drink water I then realize I am very thirsty, and will consume 24-32 oz very quickly. Afterwards I feel great, re-energized.

But my body/autonomous system 1 still hasn't learned this, and it has now been a few years since first making this realization. So odd.

Anecdotally I've noticed adding electrolytes seems to help reduce the incidence of headaches and possibly migraines, at least according to what my family members say.


Try out https://takesip.com/ app for macOS. Find out your recommended level of water intake: https://takesip.com/calculator/. Cheers.
There’s a Huberman Lab for that: https://youtu.be/at37Y8rKDlA

He cites more evidence showing that even moderate dehydration (when you aren’t thirsty) leads to lower performance (mental and physical). And talks about overhydration and hyponatremia. IIRC also discusses how hydrating at different times of day affects you, turns out your kidneys dump water quickly if you drink too late. So hydrate before six.

Yeah I noticed I was tired in the afternoon and then not tired after dinner. It was because I wasn't drinking water.
Should we avoid coffee ?
Easily one of the nicest part of wfh is the frictionless bathroom experience. No long walks. No mess, no smells or grunts from others. No trying to find time to even do it at all, just up and go. As a heavy water drinker I could easily be going once an hour. The office was literal torture some days, stuck in ‘important’ meetings with what feels like a knife in your gut and practically running out before small talk ropes you in for another 20 minutes. It’s a certain kind of hell for sure.