Medically reviewed by Daniel Combs, MD Benadryl (diphenhydramine) is an over-the-counter (OTC) antihistamine commonly used to treat allergies that is also sometimes used as a sleep aid for insomnia.

Medicines like Advil PM or Tylenol PM contain diphenhydramine to help people feel sleepy. Not everyone reacts that way, however. One reader told us: “People use Benadryl as a non-addicting sleeping ...