Trait and state irritability in young adults: daily affective dynamics and associations with physical and mental functioning

Irritability is a common and functionally impairing affective experience in young adults, yet its momentary dynamics and connections to everyday functioning remain poorly understood in non-clinical populations. Using ecological momentary assessment, this study examined how stable trait irritability relates to fluctuating state irritability in college-attending young adults, and how these dimensions are differentially associated with daily physical and mental functioning in the context of perceived stress and affective states. Trait irritability was associated with poorer physical functioning but showed no statistically meaningful association with mental functioning, suggesting a more enduring connection with somatic and activity-related domains. In contrast, state irritability emerged as the primary within-person correlate of impaired mental functioning, with only a modest association with physical functioning, indicating that day-to-day fluctuations of irritability are more related to impairments in psychological well-being. Both between-person differences and within-person changes in perceived stress and negative affect were linked to corresponding shifts in state irritability. Positive affect notably was associated with better daily functioning across physical and mental domains. Together, these findings position irritability as a multidimensional construct with distinct trait and state pathways to physical and mental functioning, underscoring the importance of contextual stress and affective states in the expression of irritability.