Associations between objective sleep duration, sleep duration variability, and sleep onset with emotion regulation and internalizing symptoms in adolescents: findings from the ABCD® study.

) year 4 follow-up; mean age 14.09 ± 0.69, 51.86% female, controlling for age, sex, race/ethnicity, and parental education. Mental health outcomes were internalizing symptoms (emotional distress directed inward) and emotion regulation, including cognitive reappraisal (reframing emotional situations) and expressive suppression (inhibiting outward expression). Sleeping ≤7.05 h (β = 0.06 95% CI: 0.00-0.11, p = 0.036), higher sleep duration variability (β = 0.09 0.03-0.14, p = 0.001), with stronger effects in females (interaction: β = -0.12 -0.22 to -0.02, p = 0.020), and later sleep onset times (β = 0.06 0.01-0.11, p = 0.030) were all associated with greater internalizing symptoms. Sleep was not linked to reappraisal (all p > 0.05). Higher variability was associated with greater suppression (β = 0.09 0.03-0.14, p = 0.001). Conclusively, objective sleep features were differentially associated with mental health outcomes.