Better to just forget about your troubles, it seems:
…regular diarists were more likely than non-diarists to suffer from headaches, sleeplessness, digestive problems and social awkwardness..[the researcher] speculates that diarists buck the usual trend because instead of a single, cathartic outpouring to offload trauma, diarists continually churn over their misfortunes and so never get over them.
Writing about trauma is most closely correlated with poor health, although the researchers admit that correlation is easier to show than causation. I’ll predict a similar result will hold for personal blogs, though I don’t know of any data.
Addendum: The ever-insightful Randall Parker offers further commentary.