Most of the students in my PT class had a job during PT school, even though it was discouraged. During my first semester of PT school, I worked at 3 different jobs for a total of ~30 hours per week and did not do well. (I also had roommates who were communications majors and rarely studied, so I also had too much of a social life.) I then started working less hours (~15-20 hours per week at 2 different jobs), and I started getting much better grades, even though there were definitely times that I felt overwhelmed. If you have a job that's flexible (ie-would let you work less hours around finals week), 15-20 hours per week of working is probably reasonable if you make school your first priority. Looking back, I wish I would have worked less hours and spent more time studying, but I have no idea how I would have gotten through school without working. I would say give it a try, and if you are completely overwhelmed and not doing well in school, cut back. Everyone can handle different workloads and amounts of sleep.