GFX is correct, breathing exercises do help stressful events. But are they exams for College or High School. Exams can be stressful, but do not worry about them. As long as you study for them, you should do fine. I would quit worrying so much about the exams and try to fill in some time to alleviate some stress. Try hanging out with friends, hang out with your family, hell, even Sythe it up! Just don't let the exams get to you. They will eventually be over, and then you should be back to normal.