RESUMO
INTRODUCTION: The corona pandemic has been a life event causing negative consequences on mental health. Mental health consists of positive and negative dimensions. The present longitudinal study investigated how positive and negative dimensions changed over 15 months after the Covid-19 outbreak. Potential changes of excessive social media use (SMU) and its relationship with mental health were also investigated. METHOD: Data (N = 189) on distress (measured overall and as depression, anxiety, and stress), well-being and excessive SMU were collected at three time points (baseline, BL; 3-month follow-up, FU1; 15-month follow-up, FU2) via online surveys in Italy. Repeated analyses of variance were used to test differences among the three measurement time points. Mediational models were applied. RESULTS: Distress did not change over time, well-being decreased and excessive SMU increased significantly. The relationship between distress at BL and excessive SMU at FU2 was significant (total effect, c: p < .001). The relationship between distress at BL and well-being at FU1 (a: p < .001), and between well-being at FU1and excessive SMU at FU2 (b: p = .004) was significant. Including FU1 well-being in the model, the relationship between distress at BL and excessive SMU at FU2 was not significant (direct effect, c': p = .078). The indirect effect (ab) was significant. CONCLUSION: Well-being mediated the relationship between baseline stress and excessive SMU. Enhanced stress may reduce well-being which, in turn, increases the risk of excessive SMU. This emphasizes the urgency of programmes that foster well-being, especially during stressful events such as a pandemic.