Introduction: This study examined daily fluctuations in the unmet interpersonal needs of thwarted belongingness and perceived burdensomeness in response to daily negative social interactions, as well as the moderating role of respiratory sinus arrhythmia (RSA) across adolescents at lower and higher risk for suicidal ideation.

Methods: Fifty five adolescents with major depressive disorder (MDD, i.e., higher-risk group) and without MDD (i.e., lower-risk group) completed measures of resting RSA, and daily measures of negative social interactions, perceived burdensomeness, and loneliness, as a proxy for thwarted belongingness, for 10 consecutive days. Within-person analyses examined the association between daily negative social interactions and unmet interpersonal needs, and the moderating roles of RSA and higher-risk group status. Between-person analyses also examined the association between RSA and unmet interpersonal needs across groups.

Results: At the within-person level, participants reported more unmet interpersonal needs on days when they reported more negative social interactions. At the between-person level, higher RSA was associated with decreased loneliness in both groups, and decreased burdensomeness among the higher-risk group.

Conclusions: Negative social interactions are associated with daily unmet interpersonal needs. Higher RSA may serve as a protective factor mitigating risk for unmet interpersonal needs, particularly burdensomeness, among adolescents at higher risk for suicidal ideation.