Self-Control Mediates Momentary Mindfulness and Affective States in Daily Life: A Dynamic Structural Equation Modeling Approach

Objectives. Mental health concerns remain widespread among U.S. college students, and momentary positive affect (PA) and negative affect (NA) are dynamic, modifiable indicators of longer-term mental health outcomes. Mindfulness is consistently associated with better affective well-being, yet the momentary mechanisms linking state mindfulness to affect remain unclear. This study tested whether perceived self-control mediates this association at the within-person level in college students’ daily life. Method. Undergraduate students ( N = 282) completed up to six ecological momentary assessments (EMA) per day for seven days (7,622 observations). Momentary mindfulness, perceived self-control, PA, and NA were assessed at each prompt. Two contemporaneous 1-1-1 dynamic structural equation models tested within-person mediation in Mplus 8.9, separately for PA and NA. Models adjusted for first-order autoregressive effects and relevant momentary, temporal, and person-level covariates. Results. Moments of higher-than-usual mindfulness were associated with higher-than-usual perceived self-control, which in turn was associated with higher PA and lower NA. The within-person indirect effects were credible for both outcomes (PA: ab = 0.077, 95% CrI [0.062, 0.091]; NA: ab = −0.080, 95% CrI [−0.096, −0.064]), along with credible direct effects, indicating partial mediation. Notably, perceived self-control accounted for a larger proportion of the mindfulness–NA association than the mindfulness–PA association, 46.0% versus 25.4%. Conclusion. Findings provide within-person evidence that perceived self-control partially mediates the association between state mindfulness and affective states in daily life. Momentary perceived self-control may be a promising tailoring variable for just-in-time adaptive interventions delivering brief mindfulness-based micro-prompts for affect regulation in college students.