Quality beats quantity: Predicting affective states by different sleep indices in psychiatric patients with suicidal thoughts and behavior.
Sleep disturbances are a transdiagnostic risk factor for affective dysregulation, which is assumed to mediate the association with suicide-related thoughts and behaviors (STBs). Yet most ecological momentary assessment (EMA) studies rely on single-night sleep metrics. With the aim of examining the link between sleep and affect, this study compared the predictive utility of multiple EMA-derived sleep indices with raw sleep measures in a sample at high risk of STBs. Following discharge, psychiatric inpatients with recent suicidal crises (N = 136) completed EMAs of sleep quality (SQ), total sleep time (TST), and affect. Multilevel models examined whether cumulative or variability-sensitive sleep indices better predicted next-day positive and negative affect (PA, NA) and affective instability compared to raw scores. Cumulative SQ, indexed by a three-night pile-up measure, consistently outperformed raw SQ and alternative indices in predicting higher PA and lower NA at both within- and between-person levels. In contrast, TST indices showed no robust associations with affect. These findings highlight cumulative sleep quality as a clinically relevant marker of short-term affective vulnerability. Future studies should explore whether this translates into increased STB risk to explore potential implications for risk monitoring and just-in-time interventions.