School start times and racial disparities in early adolescent sleep

Many communities in the United States are delaying school start times to improve youth sleep. Racial disparities exist in sleep. The extent to which school start times are associated with racial disparities in sleep is unclear, especially in early adolescent populations that are not the focus of research on school start times. This study examined the associations between school start times and actigraphy-assessed sleep, including duration, onset, and offset times among a national sample of racially diverse early adolescents.

In a national sample of 3522 early adolescents (M_age = 11.49, SD_age = 0.50; 2123 (60.3%) non-Hispanic White, 316 (8.7%) Black or African American, 768 (21.6%) Hispanic or Latinx American, 104 (2.9%) Asian American, 110 (3.0%) White-Black biracial, and 125 (3.5%) White-Asian biracial) in the Adolescent Brain Cognitive Development (ABCD) Study, links between school start times and sleep duration, onset, and offset times (mean levels, variability) were estimated by racialized groups, accounting for covariates.

Later school start times were associated with longer weekday and weekend sleep duration, later onset, and later offset (βs = 0.087 -0.145, ps < .005) among White early adolescents. Among Latinx early adolescents, the association between school start times and weekday sleep duration was weaker compared with White adolescents (b = -0.088, SE = 0.029, p = .03). School start times were unrelated to sleep duration for other racially minoritized early adolescents (βs = -0.124 to 0.124).

The benefits of later school start times for sleep duration were only evidenced for White early adolescents. This study highlights the value of including school start times as a determinant of sleep health equity.