Mel: It's true that Benadryl (diphenhydramine hydrochloride) is an anti-histamine, but it's also a common sleep aid, look at Zzz-quil for example. I don't think you'd be abusing it if you took a dose.
A full, adult dose (50 mg) of it gives me medicine head and makes me groggy the next day. To avoid this, I take a child's dose (12.5 mg) and usually wake up refreshed when I take it.