Stress (help?)

I start back at school tomorrow, I'm going to be in grade 10.
Ah yes, school. What I would like to refer to as the ultimate stress. I'm a pretty average student, I'm lucky to get 3 A's out of 7 subjects. (that was my last terms marks, for my art class, another art class and english - which was on Romeo and Juliet). Anyway, I have really bad stress issues, e.g losing weight, no sleep. I don't even get why, I mean, I have friends at school and in a few of my classes but I can't control my stress. Any advice?

On a better subject, I painted my room. It was cream and it is now purple. :D

Nothing else to add, except my stress level is already above normal standards, comments and advice would be appreciated.