In one successfully replicated study he asked a group of jobless engineers — not a stereotypically touchy-feely profession — to write about their thoughts and feelings (any personal subject) daily for 20 minutes. A control group didn’t write. Both groups continued to look for work.
Those who journaled were five times more likely to get work (26 percent) than those who didn’t journal (5 percent) during the study period. The journalers didn’t get more interviews, but they were more likely to get hired. Why? Going through the exercise of writing out thoughts and feelings — adding the physical to the mental — reduces stress by putting people literally in closer touch with them, sort of ordering thoughts and physically externalizing them so they can purge associated emotion.
The result is less stress and more clarity. Think of it as written meditation.
Pennebaker also says people who journal go to the doctor less often. Other studies have linked journaling or personally expressive writing to improved immunity and reduction of arthritis and other pain, asthma, and some PTSD symptoms. It’s been linked with improved liver function and lower blood pressure. Researchers in New Zealand found that people with skin wounds healed faster when they wrote in diaries about their deepest feelings.
http://www.cdapress.com/columns/sholeh_patrick/article_0a22a78a-af74-11e5-b3e8-cbd21dd7a785.html