Objective: This study aimed to investigate the associations between indices of family socioeconomic status and sleep during adolescence and to examine whether measures of hypothalamic-pituitary-adrenal (HPA) axis functioning mediate the observed associations.
Methods: A total of 350 ethnically diverse adolescents (57% female; mean [standard deviation] age wave 1 = 16.4 [0.7] years) completed a three-wave longitudinal study in which sleep and cortisol data were collected at 2-year time intervals. Sleep duration, latency, and variability were assessed via actigraphy during a period of 8 days per study wave. Salivary cortisol was collected across 3 days per study wave to assess cortisol diurnal slope, area under the curve, and the cortisol awakening response. Adolescents' caregivers reported their education levels, family income, and economic hardship.
Results: A greater family income-to-needs ratio was associated with longer adolescent sleep duration ( b = 2.90, p = .023), whereas greater parental education was associated with shorter sleep duration ( b = -3.70, p = .030), less sleep latency ( b = -0.74, p = .016), and less variability across days ( b = -2.06, p = .010). Diurnal cortisol slope statistically mediated the association of parental education with sleep duration ( b = -0.48, 95% confidence interval = -1.099 to -0.042), but not the association of income-to-needs ratio with sleep duration.
Conclusions: Findings suggest that parental education and family resources may have unique impacts upon sleep and HPA axis functioning during the period of adolescence. Future research is needed to examine family and behavioral factors that may underlie socioeconomic status associations with adolescent sleep and HPA axis functioning.
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