Abstract
Sleep difficulties may be one explanatory factor in the association between depression and insulin resistance; yet, explicit tests of this hypothesis are lacking. We determined if there was an indirect effect of depression symptoms on insulin resistance through sleep duration in adolescents at risk for excess weight gain. We also investigated whether dispositional mindfulness moderated the interconnections among depression, sleep, and insulin resistance. Ninety adolescents (14.2 ± 1.6y; 50% female) at risk for excess weight gain (body mass index [BMI, kg/m(2)] z score 1.6 ± 0.6) participated in the cross-sectional, baseline phase of a health behaviors study. Depression was assessed with the Center for Epidemiologic Studies-Depression Scale, sleep duration with the Sleep Habits Survey, and mindfulness with the Mindful Attention and Awareness Scale. Homeostatic model assessment of insulin resistance was determined from fasting insulin and glucose. The product-of-coefficients method was used to test the indirect effect of depression on insulin resistance through sleep duration, accounting for age, sex, BMIz, puberty, and socioeconomic status (SES). Dispositional mindfulness was tested as a moderator of the associations among depression, sleep, and insulin resistance. There was a significant indirect effect of depression on insulin resistance through sleep duration, controlling for age, sex, BMIz, puberty, and SES, 95%CI [0.001, 0.05]. Dispositional mindfulness moderated the association between sleep duration and insulin resistance, such that lower sleep duration related to greater insulin resistance only among adolescents with lower mindfulness (p < .001). Short sleep may be one explanatory factor in the depression-insulin resistance connection in adolescents at risk for excess weight gain. Adolescents with poorer mindfulness and short sleep are at highest risk for insulin resistance, whereas higher mindfulness may be protective.