Excited better than calm for test performance
Getting excited before a test improves performance better than trying to calm down. Experiments at Harvard showed that performance on anxiety-inducing activities, like public speaking an math tests, are improved when students get excited because they are thinking about how well things could go. Trying to calm down puts the focus on how things could go wrong.
http://www.sciencedaily.com/releases/2013/12/131223083917.htm