Answer: If the only medication you are taking is sulfasalazine an OTC sleep medication (diphenhydramine/benadryl)shou... have no interaction. If you are not having any pain, plain old benadryl should do the trick. Make sure you have several hours to sleep or you might feel fuzzy/hung over. I am assuming no other med conditions/allergiesI think there is a potential interaction between a sleep aid and your medication, because they both work on the central nervous system. Your best bet would be to call a health hotline in your area and talk to a nurse who could advise you better.