Zzzquil and benadryl are both diphenhydramine (which is also in PM versions of ibuprofen/acetaminophen). Makes some people calmer with the sleepiness, makes some people agitated.

I know if I'm being aggressive in the ER to the point I need to be chemically restrained they usually start with a shot of zyprexa, then when that doesn't work (it usually doesn't) another, and if that doesn't work they give me a shot that has diphenhydramine, lorazepam, and haloperidol in it and that usually chills me out some (obviously there's other shyt in there that's doing it's thing, but there's a reason they add the diphenhydramine because typical reaction is sleepiness)