Is A Sleep Disorder Due To Paracetamol And Codeine Or Pain?

following surgery to shoulder, i have been prescribed paracetamol and codeine for pain relief. I have now streamlined intake at two 500mg parac 5 times a day, last intake around midnight and one 30mg codeine morning, lunch and dinner only. I am still struggling to get a good night sleep and seem to be stuck in endless dreams, which is new to me, and get no rest, usually getting up around 4-5am to go to loo. Is the medication having an influence on this or is it something to do with pain/restrained sleeping position? thanks