Writing entries for an Internet blog may be similar to taking a vitamin or exercising, in a sense. Evidence supporting that belief is being explored by researchers who see therapeutic value from blogging or posting an online journal. "Writing about personal experiences, thoughts and feelings . . .improves memory and sleep, boosts immune cell activity and reduces viral load in AIDS patients, and even speeds healing after surgery," says a recent article in Scientific American magazine.

Explanations include the possibility that blogging brings an "endorphin rush" from the release of natural chemicals such as serotonin and dopamine - also produced by strenuous exercise and pleasurable experiences, such as listening to music or viewing art. Bloggers also may get a mental and physical lift from positive feedback comments, which create a feeling of connection and common ground. Even the stimulation of online debates with critics can be healthy - a form of brain workout.

A medical journal study published this year says cancer patients who did expressive writing of any kind just before treatment "felt markedly better, mentally and physically, as compared with patients who did not." In response to the new findings, some hospitals are developing programs that include blogging as a supportive care tool.

Blogger says: "I certainly feel better after I blog. For me it is a form of mental exercise, like sit-ups or push-ups. Blogging is how I exhale my mental carbon dioxide." - Tom Abate, journalist in San Leandro, Calif.

Patient says: "FaceBook and blogging have allowed me to keep people up to date with the exact mechanics of my treatment plan for lung cancer, and has also afforded me an outlet to explore the wry side of the entire cancer phenomenon." - Comment from 'Luke' in Melbourne, Australia, on Scientific American site

Ongoing research: A University of Texas psychologist is studying the impact of expressive writing on biological changes that increase health, such as improved sleep. "I think the sleep angle is one of the more promising ones," says researcher James Pennebaker