"PM Pain Relievers" in the United States at least, are almost always going to be Diphenhydramine in addition to the analgesic. I can only imagine that it's a concerted effort on the part of the drug companies to keep the public in a state of vague confusion, but essentially all OTC sleep aids are going to be either Diphenhydramine (Benadryl) or Doxylamine (Unisom) more rarely. I saw a couple years back that Vicks came out with Zzzquil or whatever the fuck as if it's something new and brilliant, when really, it's just an overpriced, brand-name, liquid Diphenhydramine.
You'll meet many Americans who don't experience pain, but think that "Tylenol PM" is the appropriate medication to take before bed. I'm sure Tylenol loves this, but you can save yourself some dough by shopping for raw Diphenhydramine at Wal-Mart or Costco.