Study objective: The aim of this study was to assess sleep behavior, sleep problems and mental health in childhood as possible candidate precursors for the development of delayed sleep phase (DSP) during adolescence.
Methods: A longitudinal cohort study of 2200 children at age 7-9 (T1), 11-13 (T2), and 16-19 (T3) years. DSP was assessed at T3, and mental health problems by the Strength and Difficulties Questionnaire and time in bed and sleep problems at T1 and T2. Logistic regression analyses were used to examine associations between sleep and mental health at T1 and T2, and subsequent DSP at T3. Estimated marginal means were computed to compare mental health at T1 and T2 in adolescents with and without DSP.
Results: Sleeping less than 9 hours per night at age 11-13 was significantly associated with DSP at 16-19 years (adjusted odds ratio = 3.37). Sleep problems at 11-13 years of age were more frequent among those who developed DSP compared to children who did not develop DSP (20% vs. 12%) but the results did not remain significant when controlling for early mental health problems. Sleep problems and mental health at 7-9 years of age was not related to later DSP. In the crude analyses, all Strengths and Difficulties Questionnaire (SDQ) subscales at 11-13 years was significantly associated with later DSP, but in the fully adjusted analysis, only the SDQ total score and hyperactivity subscale remained statistically significant.
Conclusion: Children with DSP in adolescence possess identifiable risk indicators in childhood.