FDA approved for use as a sleep aid in 1989. This is the active ingredient in Benadryl, Sominex, and many others.
FDA approved for use as a sleep aid in 1978. This is the active ingredient in Unisom Sleep Tabs, Nyquil, and many others.
This is not sold as a stand-alone sleep aid in the US. It is found in Bayer PM where it is mixed with aspirin, Advil PM where it is mixed with ibuprofen, and Excedrin PM where it is mixed with acetaminophen. BECAUSE OF THE DANGER OF LIVER DAMAGE HAMS RECOMMENDS THAT PEOPLE WHO DRINK ALCOHOL AVOID ACETAMINOPHEN. Advil PM was FDA approved as a sleep aid in 2005.
25 mg of diphenhydramine HCl and 38 mg of diphenhydramine citrate are to all intents and purposes identical in effect--the only difference is the salt used to bind the diphenhydramine which has no effect after it enters your body. If you feel a need for both a pain killer and an antihistamine to help you sleep then it is far more cost effective to buy a generic version of Benadryl and a generic form of ibuprofen or aspirin than to buy something like Advil PM or Bayer PM where they are premixed for you. AVOID ACETAMINOPHEN BECAUSE OF THE DANGER OF LIVER DAMAGE. Doxylamine is chemically distinct from diphenhydramine and some people may find that one is more effective than the other. We recommend that you avoid name brands which cost much more and buy cheap generics from Amazon or your local stores. If you buy from the HAMS link to Amazon then Amazon will donate a part of the purchase price to HAMS at no extra cost to you.
Rickels K, Morris RJ, Newman H, Rosenfeld H, Schiller H, Weinstock R. (1983).Diphenhydramine in insomniac family practice patients: a double-blind study. J Clin Pharmacol. 23(5-6), 234-42.