0208 Sleep Irregularity Predicts Emotional Change After Sleep Restriction Among School-aged Children

Abstract Introduction Sleep irregularity has been associated with more negative emotional outcomes in adolescents and young adults. Although commonly used, standard deviation of sleep duration may be a less sensitive metric of sleep regularity in school-aged children given increased need for sleep and parental influence on sleep timing during childhood. We therefore examined another metric of sleep regularity, mean sum of successive differences (MSSD), in association with children’s responses to emotional stimuli when rested and after partial sleep restriction. Methods Healthy children (N = 50, 7-11 years, M age = 9.65; 56% female) wore actigraphs for one week from which MSSD of sleep time (TST) and midsleep point (MSP) was calculated. Both after a night of full sleep and after two night of sleep restriction (SR; 7 and 6 hours sleep), participants were asked to suppress their facial expressions in response to negatively valanced movies while respiratory sinus arrythmia (RSA), a measure of physiological emotional regulation, was monitored. Participants also rated difficulty of emotional suppression (ES). Hierarchical linear regressions were run with change in RSA during negative movies and difficulty of ES while rested and after SR as dependent variables, and regularity metrics as independent variables. Average TST and pubertal status were entered as covariates, as well as resting RSA and change in resting RSA after SR in relevant models. Results Sleep regularity did not predict emotional variables when children were rested. However, greater TST MSSD (β=0.26, p=0.02) predicted increased RSA during movies after SR, suggesting greater difficulty regulating emotional responses (overall model: F(4,28)=3.12, p=0.03, addition of TST MSSD: ΔR2 = 0.15, F(1,28)=6.21, p=0.02). Additionally, greater MSP MSSD (β=-0.9, p=0.0003) predicted less ES difficulty post SR, indicative of blunted affective expression (overall model: F(3,46)=6.22, p=0.001, addition of MSP MSSD: ΔR2=0.24, F(1,46)=15.27, p=0.0003). Conclusion Irregularity in TST may exert the greatest impacts on school-aged children’s physiological emotional responses when sleep duration is inadequate. Analyses also suggest a blunting effect of irregular sleep timing on emotional expression after inadequate sleep duration. Our findings warrant further exploration. Support (if any) Data collection was supported by grant #R21MH099351