Ah, Benadryl, my first venture into "lets take a bunch of this and see what happens". It used to knock me out when I was younger, but I was (stupidly) taking 6-7 of the things at a time.
Definitely try the midnite stuff if you can find it, one tablet of it put me out and didn't make me feel all sluggish and gross. NyQuil, eh, it does the job but it tastes like Dawn soap. Don't ask me how I know that.