Increasing student well-being through a positive psychology intervention: changes in salivary cortisol, depression, psychological well-being, and hope.

The significant prevalence of mental health problems among children and adolescents is a major concern worldwide. The current study evaluates the impact of a year-long, school-based intervention, Flourishing Students, on adolescents' salivary cortisol levels, depressive symptoms, psychological well-being, and hope. Utilizing a cluster randomized design with intervention and control classes, 72 students engaged in 32 well-being lessons during academic year 2016-2017, whereas 68 students followed their standard curriculum. Depressive symptoms and psychological well-being were assessed at three time points, while the stress hormone cortisol and hope were measured at two. The results showed a slight increase in cortisol levels from baseline to post-intervention during school hours in the control group, whereas no change occurred in the intervention group. Additionally, total cortisol levels at post-intervention were slightly lower among intervention-group students compared with control group students. Questionnaire data revealed significant interaction effects on psychological well-being and hope from baseline to post-intervention, and on depression and psychological well-being from baseline to the 5-month follow-up. The intervention group scored lower in depressive symptoms and higher in psychological well-being and hope compared with the control group. These findings underscore the essential role of comprehensive assessment methods in evaluating intervention efficacy in well-being programs.