In two lab studies, researchers dried people out on purpose, until they'd lost 1 to 2% of their body weight in water. One study was 26 men, the other 25 women. Both felt more tired. The women's mood dropped; the men got more tense and slipped on some attention and memory tests. Evidence: decent
That was dehydration made in a lab, in two small studies from one lab, with co-authors from a company that sells bottled water. The studies didn't test an ordinary day at a desk. And "eight glasses a day" has no good evidence behind it. Evidence: decent
The practical version: don't go thirsty for hours because the water is across the room. Evidence: worth trying
Same theme: Fuel
Fuel
Go easy on the big energy drinks
Don't drink the big cans or several in a row. Heart condition, high blood pressure or stimulant medication? Skip energy drinks completely.
no timeEvidence: worth trying
Fuel
The afternoon dip isn't the sandwich
Put easy work in the early afternoon, whatever you ate for lunch. Don't reach for something sweet to fix the slump.
no timeEvidence: decent