Anecdotally, I always make myself drink a full glass of water before bed if I've been drinking, and give the same to anyone I've been drinking with, and it seem

Anecdotally, I always make myself drink a full glass of water before bed if I've been drinking, and give the same to anyone I've been drinking with, and it seems to prevent hangover every time. Correlation is not causation, of course, but it can't hurt.