Rumination as a Mediator and Moderator of the Relationship between Unpleasant Events and Unhappy Mood: A Daily Diary Study

Abstract

Research is lacking on whether and how stressful events trigger ruminative episodes and whether and how rumination, in turn, exerts a perpetuating influence on negative mood on a daily basis. To answer these questions, an experience sampling study was conducted with 101 undergraduate students who reported momentary unpleasant events, rumination, and unhappy mood once a day for 30 days. Our findings showed, as expected, that daily rumination mediated the relationship between daily unpleasant events and daily unhappy mood. A significant daily moderation finding was also obtained: rumination exacerbated reports of unhappy mood under low levels of unpleasant events. Day to day stability was noted for momentary rumination and unhappy mood, and these two variables also exhibited a weak bidirectional relationship over contiguous days. And finally, a moderated mediation analysis showed that individuals who reported high trait rumination evidenced a stronger indirect effect in the daily mediation pattern. The new findings suggest that: 1) rumination functions as a daily mediator and moderator of the basic stress to depression relationship; 2) rumination perpetuates negative mood over time; and 3) rumination is a stronger predictor of negative mood from day to day than stressful events. These findings illuminate how psychopathological interpretations of day to day life experiences can lead to negative mood states in a community sample.