How to use it
Losing just over 1% of your body weight in sweat is enough to lower mood and focus and bring on headaches. Drink during every session, not only after. Pale-yellow urine is the check.
How sure we are
P Evidence: promising. Good studies, but small or few. Use it and keep checking.
Sources
At 1.36% dehydration, healthy young women had worse mood, more fatigue, lower concentration and more headaches; most thinking tests didn't change (Armstrong et al. 2012, 25 people, crossover RCT, 🟡) · via Louisa Nicola.
Not medical, legal or financial advice.