Effective emotion regulation (ER) is integral to adolescents’ mental well‐being and socioemotional development. During adolescence, peer interactions have an increasingly salient influence on the development of effective ER, but not all supportive peer interactions support adaptive ER. Co‐rumination reflects the tendency to seek ER support by engaging with peers in negatively focused discussion of ongoing problems. We examined associations between co‐rumination (state and trait) with measures of individual's autonomic (i.e., respiratory sinus arrhythmia, RSA) and affective regulation (self‐report) among 30 female close‐friend dyads (ages 11–17; 74% White) while engaged in a support‐seeking discussion in the laboratory. We found that trait co‐rumination corresponded with RSA withdrawal during peer support, suggesting a potential mechanism by which co‐rumination contributes to dysregulated ER. We also examined dyadic patterns of physiological regulation via prospective change actor partner interdependence models (APIM). Partner effects were moderated by behaviorally coded state co‐rumination. Dyads with high state co‐rumination displayed coupled RSA movement in opposite directions, while dyads with low state co‐rumination exhibited coupled RSA movement in the same direction. These findings are consistent with similar physiologic linkages in close relationships observed in other developmental periods. Results highlight the importance of multimodal assessment for characterizing social ER processes across development.

Trait dysphoric rumination is a transdiagnostic factor associated with depression and anxiety that has also been linked with blunted respiratory sinus arrhythmia (RSA), an index of reduced emotion regulation capacity. However, the autonomic correlates of state dysphoric rumination remain unclear. We examined the physiological correlates of state dysphoric rumination and the potential repairing effects of savoring on autonomic functioning. To provide a comprehensive assessment of autonomic correlates, we examined changes in parasympathetic (RSA) and sympathetic (cardiac pre-ejection period, PEP; and electrodermal activity, EDA) arousal independently, as well as autonomic coordination among indices. Eighty-two women (ages 18-25) completed laboratory physiological assessments, including rumination and savoring tasks, and self-report measures of trait rumination. Dysphoric rumination was associated with sympathetic activation (i.e., decreases in PEP, increases in EDA), and subsequent Savoring following a recovery period also corresponded with decreases in PEP. Trait rumination did not predict autonomic changes during state rumination. However, higher trait rumination was associated with greater sympathetic coordination (PEP-EDA correspondence) during savoring. In summary, dysphoric rumination co-occurred with sympathetic activation, and subsequent savoring successfully recruited sympathetic activity (PEP) redirected on positive moods and events. Results also emphasize the utility of examining sympathetic and parasympathetic indices, and coordination among autonomic indices to delineate autonomic activity associated with emotion regulation strategies.