It is perfectly normal to feel a certain amount of nervousness or tension before a test or important event. You must first determine the kind of anxiety you are feeling. If your anxiety stems from a lack of preparation for the exam, consider your reaction to be normal and rational. While both of these anxieties are considered to be normal, it is helpful to know how to overcome their effects.
Preparation is the key to minimizing rational anxiety.
Attempting to absorb a semester's worth of material the night before an exam is a poor way to learn and can easily produce feelings of anxiety. This is NOT the time to start learning a large sum of material. Put together all of the information you have been given for each test and focus on mastering the main concepts of the class. When preparing for the exam, try to come up with questions that may be asked, and answer them by integrating the information you have gathered from lecture notes, supplementary readings and the textbook. If you find that you cannot cover all of the material presented throughout the semester, pick a section that you can cover well.