Adrenocortical and autonomic attunement between romantic partners in emerging adulthood.

Parent-child physiological attunement, particularly during stressful situations, appears adaptive as shared stress reactivity may promote dyadic engagement. Romantic partners eventually replace parents as the primary support figure, yet it remains unclear whether romantic partners buffer physiological stress or display physiological attunement as most studies on adults examine attunement during conflict paradigms. The present study examined physiological attunement in 63 emerging adult romantic partner dyads (one partner was the active participant, the other the observer) during the Trier Social Stress Task (TSST). Heart rate (HR) and respiratory sinus arrhythmia (RSA) were continuously monitored across the visit. Repeated saliva samples were assayed for cortisol. Physiological attunement was operationalized as a correlation in biomarkers between the TSST participant and their partner; sex, social support, and physical proximity were examined as moderators. We then compared the biomarker profiles of partnered-TSST participants to individuals who participated in the TSST solo (n = 63) to determine if partner presence buffered stress biomarker reactivity during the TSST. RSA attunement between partners was found but was not further moderated by social support or sex. Adrenocortical attunement was moderated, such that lower social support and increased proximity resulted in higher attunement. HR attunement was higher when the participant was male and when partners were in close physical proximity. Compared to TSST solo, romantic partner presence increased participant cortisol levels and altered HR reactivity, suggesting that emerging adult romantic partners do not buffer physiological stress reactivity. Future research should examine whether physiological attunement and partner presence is protective in more established relationships.