I have a couple night/early morning classes this term and as a commuter student am finding it really difficult to get home at 12:30 am and have to wake up at 5:30 am the next day to go back to school. I was wondering if anybody here has heard of people sleeping in the student centre ovenight(ive seen people nap, but never seen anyone actually nap overnight for a long period of time). I'm just picturing a custodian telling me to go home or something?

Related to this, are the showers in the gym free to use or do you need a gym memberhip? If so, how weird would it be to just randomly walk in and shower, then sleep in student centre? Also, does anyone know if locker space is still available? I heard they sell out the first week of classes.

During exams people sleep there all the time. My friend did lol. So to answer your question, yes you can most definitely sleep there.
As for showers you don't need a membership to use the showers, but I'm not sure if the building is open late at night. I'm not too sure about the lockers either but you can try and get one (I think registering for a locker is done in the campus bookstore), or maybe share with a friend? That's what I did last year.

I worked at the office that deals with the Student centre building, and we never had to kick people out overnight unless the student centre was closed (i.e. no one is working in there), which happens over the holidays, expecially reading week and xmas break. Thats when my boss wanted to make sure people were kicked out overnight.

Yeah, I would recommend the top levels of the student centre, though, if you want to feel a little safer.