interstitial cystitis
"Definitely helped keep me asleep, but when I woke up the next morning, the first morning void (urination) was painful from not going during the middle of the night!  Plus, I had a groggy, hangovers like feeling the entire next day.  Skipped a day to make sure the Atarax was the reason, then when I took it again, same exact thing.  It doesn't knock you out, but it does help with nocturnal.  At this point, I'd rather wake in the middle of the night to void instead of waking up in so much pain with a hangover that I didn't at least enjoy getting.  Plus, holding it in increases your UTI chances, and those are doubly not fun with IC."