What Is The Ingredient Of Lortab Pill?

I had a nose operation about 4 months ago and the Dr. prescribed LORTAB 7.5 TAB for pain, (actually the generic hydroco/apap), as it turned out I didn't need any for pain. However since then I had some other pain so I have taken one at bed time three different times. I am 75 years old and have trouble getting a goods nights sleep but when I take one of thes pills I sleep all night like a baby. What I would like to know is what ingredent in these pills makes me sleep so good and can I get it over the counter. Also what are the bad side effects if I take it regular? Please advise.