I use a first gen antihistamine (diphenhydramine) as a sleep aid when I need one. One 25mg tablet is typically plenty. Sometimes I’ll even take half. Definitely don’t take two unless you don’t want or need to wake up at any particular time the next day. It usually makes me feel groggy the whole next day if I do so I mostly try to reserve it for extreme situations like combating jet lag from a long-haul flight.
ETA: Just noticed what sub I was in so not really sure this is appropriate advice. Leaving it up anyway just in case 😅