Impulsivity Mediates the Effect of Sleep on Alcohol Use Among Middle Schoolers

Introduction: Poor sleep quality among adolescents has been linked to early initiation of alcohol use and subsequent alcohol-related problems (Miller, Janssen, & Jackson, 2016). Recent studies identify impulsivity as a potential mediator of this association (Warren, Riggs, & Pentz, 2017); however, this finding is not well-replicated and the role of different dimensions of impulsivity are not well understood. Here, we examined two underlying facets of impulsivity—acting-without-thinking (AWT) and attentional control (AC)—as potential mediators of the effects of sleep latency (how long it takes to fall asleep), daytime sleepiness (difficulty staying awake in the daytime), and average sleep duration (mean hours of sleep per night), on alcohol use initiation.

Methods: Survey data were collected from 7^th and 8^th grade students in public middle schools (N = 345; Mage (SD) = 12.65 (±0.67) years; 46% female; 59% non-Hispanic White, and 29% Hispanic), at two time points, T1 and T2, assessed six months apart. Daytime sleepiness was assessed using the Pediatric Daytime Sleepiness Scale (Drake et al., 2003). Sleep latency was measured by asking, “after going to bed, how long does it usually take for you to fall asleep?” Average sleep duration was obtained by taking the mean of self-reported hours of sleep for weekdays and weekends. AWT was measured using 9 items from the Junior Eysenck Impulsivity Scale (Eysenck et al., 1984). AC was assessed with the attention sub-scale in Rothbart’s Early Adolescent Temperament Questionnaire (Rueda, Posner, & Rothbart, 2005). Additionally, participants were asked at T1 and T2 if they ever had a drink of alcohol (Y/N). We used Logistic regression models to examine our binary outcome (alcohol use), and tested mediation using the delta method (Sobel, 1982) with robust estimation of standard errors. Alcohol use at T2 was the main outcome variable; all other measures were from T1 assessment. Analyses controlled for students’ age, gender, race-ethnicity, free/reduced lunch eligibility.

Results: AWT dimension of impulsivity significantly predicted alcohol use at T2, controlling for T1 alcohol use, B(SE) = 0.02(0.04), p = 0.03; AC did not have a significant effect, B(SE) = 0.01(0.01), p = 0.27. Daytime sleepiness was significantly related to AWT, B(SE) = 0.20(0.03), p < 0.01, and to alcohol use at T2, B(SE) = 0.01(<0.01), p = 0.03. Further, mediation analyses revealed that AWT fully mediated the association between daytime sleepiness and alcohol use, B(SE) = 0.01(<0.01), p = 0.04. Daytime sleepiness had no direct effect on alcohol use when accounting for the mediated pathway through AWT, B(SE) = 0.01(<0.01), p = 0.38.

Conclusion: Findings suggest an association between inadequate sleep and early onset of drinking during adolescence, and that this effect may be channeled through AWT. Adolescent sleep behaviors and impulsivity are promising targets for prevention programs aimed at reducing early onset of alcohol use.