According to the April 14, 1999 issue of the Journal of the American Medical Association, (281:1304-1309, 1328-1329) patients who write about stressful events suffer less with their symptoms of allergy, asthma and rheumatoid arthritis. The stress-reducing effects of writing were long-lasting; patients experienced improvement for four months after writing about their stressful experiences.
On average, asthma patients who wrote about their most stressful life event showed a 19% improvement compared to the control group, which experienced no improvement. This was determined by a specific measure of lung function. Patients with rheumatoid arthritis who wrote about stressful events had a 28% reduction in symptoms compared to those who did not write.
Expressing negative emotion seems to have helped these patients. Writing enables them to acknowledge, and put distress and negative emotion into perspective.