Hi,
During my 3rd year I was on call q6 and we stayed in house for between 26 - 32 hours. It was quite experience but alot of fun. The thing is that as a student you will not have to do any admits usually after 2am so you get to go to the on call room and get some sleep before rounding in the am. For the new med students that are wondering what I am saying here it goes:
When on day of call you come in preround on your pts, go to morning rounds, go to work rounds, help the residents in afternoon, look up labs on your pts and fellow student's pts to help them out, do all admits that come in the afternoon until around 12am unless your resident doesn't like you then it goes until later. Get to on call room around 12 am, get some sleep, get up at 6:30 am Preround on your pts, do morning rounds, go to work rounds, then go home around 12-1pm. Hope that gives you a typical on call night for med student in most institutions and depending on how hard you want to work.
Hope that helps,
"Wish you all good luck in med school and your careers, and remember as a student if you don't know its best to fuss up and say you don't know than to utilize your semi-intelligence for a BS answer! Your preceptor WILL know! Part of being a good doctor is realizing your inadequacies and seeking help when you can! Because guaranteed, the smartest doc you know does not know everything in medicine, and guess what neither will you"