Motrin PM is for relief of occasional sleeplessness when associated with minor aches and pains; it helps you fall asleep and stay asleep. Caplet contains 200 milligrams of ibuprofen and 38 milligrams of diphenhydramine citrate. Ibuprofen is a nonsteroidal anti-inflammatory drug that is used for treating pain, fever and inflammation. Diphenhydramine is the active ingredient in Benadryl®. Motrin PM combines pain relief with an effective nighttime sleep aid.