The Economist recently published an article with some surprising research findings about stress. Contrary to popular belief, stress is not always bad, nor is it the amount of stress that matters. Rather, the key determinant of its impact on performance and health is largely psychological.
In one study, researchers divided a set of GRE test takers into two groups. Saliva samples were taken to establish baseline stress levels for all participants. Then one group was told that stress during practice exams is natural and can improve performance, while the other group just took the test. Saliva samples were taken at the end of the exam, and the results from both groups indicated similar levels of stress. BUT, the group that had learned stress can be helpful scored higher on the practice test (and, several months later, on the actual GRE) than those who just took the test.
Even more impressively, in 2012 a group of researchers scoured through a 1998 National Health Interview Survey in which participants had been asked to indicate the amount of stress they experienced over the past year and whether they believed stress was harmful. They made a surprising discovery. When they looked up mortality rates they found that those who had reported high levels of stress and believed it was harmful had a 43%(!) higher risk of premature death. Even more surprisingly, those who reported a high level of stress but did not believe it was harming their health actually had a LOWER risk of premature death than those who reported little stress. If you weren't surprised reading that, reread it.
I work with students preparing for some of the most important exams they will ever take - stress is common, and natural. The message from this research is to embrace it. Use your stress to your advantage. Not only will it help you perform better on your tests, it may even help you live longer!