Worries are problematic because they deplete a part of the brain's processing power known as working memory, which is critical to successfully computing answers to difficult test questions. Working memory is lodged in the prefrontal cortex (at the very front of our heads, sitting just above the eyes) and is a sort of mental scratch pad that allows people to "work" with whatever information is held in consciousness, usually information relevant to the task at hand. When worries creep up, the working memory people normally use to succeed becomes overburdened. People lose the brain power necessary to excel.
For several decades, psychologists has been extolling the virtues of writing about personally traumatic events in your life, such as the death of a close family member or a difficult breakup. Time and time again, psychologists have found that, after several weeks of writing about a life stressor, people have fewer illness-related symptoms and even show a reduction in doctor's visits. "