Enhancing well-being and alleviating depressive symptoms with positive psychology interventions: a practice-friendly meta-analysis
Pooling 51 interventions across 4,266 people, positive psychology exercises significantly improved well-being (r = .29) and reduced depressive symptoms (r = .31). Effects were larger for people who were depressed, older, or had chosen the intervention themselves.
The meta-analysis that made positive psychology exercises mainstream in clinical practice.
Sin and Lyubomirsky pooled 51 interventions covering 4,266 individuals. Positive psychology interventions significantly enhanced well-being (mean r = .29) and decreased depressive symptoms (mean r = .31).
Several factors changed how well they worked:
- Depression status - people who were depressed benefited more
- Self-selection - people who chose the intervention benefited more
- Age - relatively older participants benefited more
- Format and duration - individual delivery, over longer periods, worked better
Two of those deserve scepticism when you read the headline. Self-selection means some of the effect is the kind of person who signs up. And longer, individually delivered interventions performing better is partly a statement about who stays enrolled.
Read this against the 2025 PNAS gratitude meta-analysis, which was preregistered and found g = 0.19. The 2009 numbers are larger. That gap - older, non-preregistered syntheses reporting bigger effects than newer preregistered ones - is the story of psychology over the last fifteen years, and the more conservative number is the one to trust.
Self-selection was one of the factors that increased effectiveness, which means part of this result reflects motivation rather than the exercise. It covers positive psychology broadly rather than gratitude journaling specifically. The analysis is from 2009 and predates the field's replication reckoning; more recent, preregistered meta-analyses report smaller effects.
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Summarized by Tiago Martins · Last updated: · How we write these
