I know that there are pre-med students that work part-time at a hospital because they cannot work full time! It is absolutely possible to schedule your time with the hospital and figure out what shifts you can or can't work. I previously volunteered at a nursing home before and it was up to me to schedule what times I wanted to come in. However, if you are looking for a paid job in the hospital then I would suggest asking if they do offer flexible schedules. It depends based on the hospital but most should be flexible especially if you work part-time!