Coffee literally hydrates you. The fact that you believe a popular myth makes me assume you don’t really understand coffee.

The worse sleep is a fair argument, but coffee drinkers generally live by a golden rule - no coffee 6 hours before bed.

EDIT: Ffs Lemmy, it really isn’t that hard to search and learn something new instead of just downvotting.

Moderate coffee consumption hydrates you similarly to water, debunking the myth that its diuretic effect causes dehydration. While caffeine is a mild diuretic, the high water content in coffee outweighs this effect. Daily coffee drinkers develop a tolerance, allowing coffee to contribute effectively to daily fluid needs.