But if you NEED to fall asleep in the next hour 25-50mg of diphenhydramine, 1-2 normal Benadryl or Advil/Tylenol/Motrin PM(with they’re active ingredients) does a pretty reliable job if you let it. You have to get in bed and give it a shot at working but I find little failure with it. You will however be somewhat groggy in the morning, drink water.