If I am getting only 7 hours of sleep per night will it do serious mental/bodily harm?

I am 19 I am a part time (6am to 12pm) trade school student and I just picked up a job at wal-mart that is full time. The first 2 days are 1pm to 9pm so I have to leave straight from school to work. But after the first 2 days I work from 4pm to 1am and then the next day I have school at 6am ideally im waking up about 5:25am to get ready and get to school on time. Will this harm me mentally or physically?