ABSTRACT
Loneliness is a pervasive concern among young adults that has been exacerbated by the COVID-19 pandemic. Identifying factors that mitigate the negative impact of loneliness is important for protecting young adults' mental health and well-being. Among 188 undergraduates (71.8% women;77.1% White), the present study examined physiological regulation and sleep quality as moderators of the association between loneliness and adjustment. Physiological regulation was assessed via resting respiratory sinus arrhythmia (RSA), a measure of parasympathetic activity. Participants self-reported loneliness, sleep quality, mental health symptoms, and positive affect/well-being. Three-way interactions were significant, such that at higher levels of loneliness, the combination of high resting RSA and high sleep quality was protective against elevated anxiety and depressive symptoms and low positive affect/well-being. Multi-pronged, tailored interventions that target improvement in loneliness, physiological regulation, and sleep quality based on an individual's unique risk factors may best promote young adults' adjustment. © 2023 Society for the Study of Emerging Adulthood and SAGE Publishing.