While your scene is fading, your breathing should slow to about six breaths per minute. Getting to the one color should take another three seconds to a minute. Being able to do all this in a stretch can take some practice, but after getting the hang of it, you'll always find yourself using it. Now that you've cleared your body and your mind, you'll find yourself very focused. Until the test paper lands on your desk.
Some people panic at the sight of a test.
A few years ago, I did the same thing. The trick is to convince yourself the test is easy. This is called auto suggestion. Simply repeat to yourself that the test is easy. You might not believe it at first, but you will be more relaxed.