Linear and nonlinear associations between the sleep environment, presleep conditions, and sleep in adolescence: moderation by race and socioeconomic status.

ABSTRACT

OBJECTIVE/BACKGROUND: The role of the sleep environment and presleep conditions that may influence adolescents' sleep are understudied. The aims of the current study were to examine linear and nonlinear associations between the sleep environment and presleep conditions and adolescents' daytime sleepiness and sleep/wake problems. METHOD: Participants included 313 adolescents (Mage = 17.39 years, SD = 10.38 months; 51.4% girls, 48.6% boys; 59.1% White/European American, 40.3% Black/African American) from a wide range of socioeconomic backgrounds living in the southeastern United States. Adolescents completed surveys assessing the sleep environment (eg, light, bedding), four presleep conditions (ie, general worries, family concerns, arousal, somatic complaints), and sleep (daytime sleepiness, sleep/wake problems). RESULTS: Sleep environment disruptions and worse presleep conditions were positively associated with sleepiness and sleep/wake problems in a linear fashion. Nonlinear associations emerged such that levels of sleepiness increased rapidly between low and average levels of the sleep environment and two presleep conditions (worries, arousal); the slope leveled off between average and high levels. Moreover, linear effects of environmental disruptions, family concerns, somatic complaints, and presleep arousal on sleep/wake problems were moderated by race and/or SES, indicating that positive associations between some presleep conditions and sleep/wake problems were more pronounced for Black and lower SES youth. CONCLUSIONS: Results support the importance of the sleep environment and multiple presleep conditions and assessments of both linear and nonlinear effects for a better understanding of factors that may contribute to sleep. Additionally, results indicate the sleep environment and some presleep conditions may be more consequential for disadvantaged youth.