Dehydration is a primary reason for daytime fatigue & can slow down your metabolism as much as 3%
Just a 1%-2% drop in body water can impair your mental focus, concentration & physical performance.
Drinks that have caffeine like colas, coffee, or tea actually stimulate fluid loss & promote dehydration
The primary cause of a hangover is major dehydration. Alcohols and the sugars they contain deplete fluids from the body's cells and particularly the brain - a key reason for headaches, dry mouth, upset stomachs & overall malaise.