Expressive writing is known to help assuage psychological trauma and improve mood. Now studies suggest that such writing, characterized by descriptions of one's deepest thoughts and feelings, also benefits physical health.

Researchers in New Zealand investigated whether expressive writing could help older adults heal faster after a medically necessary biopsy. In the study, 49 healthy adults aged 64 to 97 years wrote about either upsetting events or daily activities for 20 minutes, three days in a row. After a time lag of two weeks, to make sure any initial negative feelings stirred up by recalling upsetting events had passed, all the subjects had a biopsy on the arm, and photographs over the next 21 days tracked its healing. On the 11th day, 76 percent of the group that did expressive writing had fully healed as compared with 42 percent of the control group.

“We think writing about distressing events helped participants make sense of the events and reduce distress,” says Elizabeth Broadbent, professor of medicine at the University of Auckland in New Zealand and co-author of the study, published in July in Psychosomatic Medicine. Long-term emotional upset can increase the body's levels of stress hormones such as cortisol, which impedes the immune system. A paper in September in the British Journal of Health Psychology indeed found that writing about an emotional topic lowered participants' cortisol levels.

The writing in Broadbent's study may have also sped recovery by improving sleep. Participants who slept more in the week before the biopsy healed faster, perhaps because sleep ramps up many bodily processes involved in healing.