The social psychologist James Pennebaker reports that keeping secrets and experiencing trauma can make people sick. In a series of studies Pennebaker found that people were able to improve both their physical and mental health by writing about their deepest secrets for 10-20 minutes daily. Subjects achieved positive results by writing in journals or diaries or practicing any form of expressive writing.

A pioneer in the field of writing therapy, Pennebaker has found a consistent link between healing from trauma and express writing. Currently a professor at the University of Texas, Austin, Pennebaker is well known for developing the Linguistic Inquiry and Word Count, a computerized text analysis program that measures psychological symptoms such as anger and fear and also topical categories such as leisure and monetary concerns based on linguistic patterns. This research confirmed earlier studies showing a link between linguistic patterns and one's personality or psychological state.

The American Psychological Association's Bridget Murray explains that expressive writing (journals, logs, questionnaires) has been used as a therapeutic tool for many years. Benefits include strengthening the immune system, which is key to healing in autoimmune diseases. In addition, expressive writing offers benefits in patients with terminal or life threatening diseases.

Murray describes the process of venting emotions, either through writing or verbally, as a therapy that may benefit some people more than others depending on how patients use it to interpret their experiences. Key is how patients use this tool to better understand and learn from their emotions. Pennebaker notes that even talking into a tape recorder helps relieve the stress that exacerbates disease symptoms. In one study, patients with rheumatoid arthritis wrote for 20 minutes daily for three consecutive days about the most stressful event of their lives while control subjects wrote about emotionally neutral subjects. Four months later the subjects who wrote about stressful events showed both objective and clinical improvement.

Book: Opening Up by Writing It Down, 3rd Ed.: How Expressive Writing Improves Health and Eases Emotional Pain