Dynamic associations between emotion regulation, mental fatigue, and stress: An ecological momentary assessment study.

The use of emotion regulation (ER) strategies, including distraction or reappraisal, is influenced by dynamic factors such as mental fatigue and stress. Mental fatigue arises from cognitive effort, including the exertion required for effortful ER, and accumulates with repeated effort. Stress also influences ER by altering emotion intensity and goals. While ER strategies are essential for self-regulation, some may increase mental fatigue and stress, heightening the risk of emotional extremes or dysregulation that may adversely impact daily life. However, the bidirectional associations between ER strategies and mental fatigue and stress remain unclear. This study examined these relationships at the within-person level using ecological momentary assessment (EMA), with surveys administered approximately 3 h apart. Specifically, this study investigated whether (1) ER strategy selection predicts mental fatigue and stress, (2) mental fatigue and stress predict ER strategy selection, and (3) the number of ER strategies implemented predicts mental fatigue. Between March and July 2024, 179 adults (74% women), aged 18-35, completed up to four EMA surveys daily over 28 days (total surveys = 10,984), reporting momentary ER strategy use, mental fatigue, and stress. Results revealed that distraction as an ER strategy was frequently used and bidirectionally predicted increases in both mental fatigue and stress, suggesting potential maladaptive effects for some people. While stress was associated with increased use of most ER strategies, no ER strategies were associated with decreased stress 3 h later. These findings highlight that considering strategy selection and timing may mitigate maladaptive ER and enhance well-being.