That's the headline from io9 - although the real story from the journal Science is a bit more subtle:

Two laboratory and two randomized field experiments tested a psychological intervention designed to improve students’ scores on high-stakes exams and to increase our understanding of why pressure-filled exam situations undermine some students’ performance. We expected that sitting for an important exam leads to worries about the situation and its consequences that undermine test performance. We tested whether having students write down their thoughts about an upcoming test could improve test performance. The intervention, a brief expressive writing assignment that occurred immediately before taking an important test, significantly improved students’ exam scores, especially for students habitually anxious about test taking. Simply writing about one’s worries before a high-stakes exam can boost test scores.

So, keeping a diary is not only handy for reflecting on what has happened in your past, but it's also good for helping you deal with your anxieties for the future.

AuthorAndrew Burke