Is Journaling good for mood & stress?

The evidence points that way, though it's not yet conclusive. Expressive-writing and journaling interventions — writing about a stressful or traumatic experience for a set period, following the classic Pennebaker paradigm — have been tested in numerous randomized controlled trials, and the accumulated evidence has not shown the general health benefit the practice is often assumed to have. That's reflected in an evidence score of 50/100 for its role in mood & stress, drawn from 5 studies (4 RCTs), with an estimated impact on longevity rated limited (30/100).