This cohort study uses the kindergarten cohort data from the Longitudinal Study of Australian Children to assess whether bidirectional associations exist between sleep problems and internalizing and externalizing difficulties in children from preschool through early adolescent years. Question Do bidirectional associations exist between child sleep problems and internalizing or externalizing difficulties that span key school transition periods from preschool age through early adolescence? Findings This cohort study used data obtained every 2 years beginning when 4983 children aged 4 to 5 years were recruited for the Longitudinal Study of Australian Children and found bidirectional associations between sleep problems and externalizing difficulties through ages 12 to 13 years. Although sleep problems were significantly associated with later internalizing difficulties, the reverse was not significant. Meaning Future studies should determine whether interventions addressing sleep problems improve both internalizing and externalizing difficulties and whether interventions targeting externalizing (but not internalizing) difficulties improve sleep. Importance Although multiple cross-sectional and longitudinal studies have established that sleep problems and behavioral difficulties are associated in children, the directionality of this association and whether sleep problems are differentially associated with different types of childhood behavioral difficulties are unclear. Understanding these associations will inform the focus and timing of interventions. Objective To determine whether longitudinal and reciprocal associations exist between child sleep problems and externalizing, internalizing, or both behavioral difficulties. Design, Setting, and Participants Prospective cohort study using nationally representative data from the first 5 waves (2004, 2006, 2008, 2010, and 2012) of the kindergarten cohort (4983 children aged 4-5 years in 2004) collected for the Longitudinal Study of Australian Children. Associations were evaluated using cross-lagged structural equation model analyses performed from May 25, 2016, to September 20, 2017. Main Outcomes and Measures Child sleep problems and internalizing and externalizing behavioral difficulties. Sleep problems were defined using parent-reported child sleep problem severity and specific difficulties (ie, difficulty getting to sleep at night, not happy sleeping alone, waking during the night, and restless sleep) on 4 or more nights of the week. Child behavioral difficulties were defined using the parent-reported Strengths and Difficulties Questionnaire for externalizing difficulties (conduct problems and hyperactivity/inattention subscales) and internalizing difficulties (emotional problems subscale). Results The 4983 children enrolled in 2004 had a mean (SD) age of 4.7 (0.2) years and comprised a similar percentage of boys (2536 [50.9%]) and girls. In 2012, 3956 children (79.4%) aged 12 to 13 years were retained. Significant bidirectional associations were detected between sleep problems and externalizing difficulties during the elementary school transition period, with greater sleep problems associated with later externalizing behavior and vice versa (cross-lagged path coefficient, 0.04 [95% CI, 0.01-0.08] to 0.09 [95% CI, 0.06-0.13]). Although sleep was a significant driver of later internalizing difficulties (coefficient, 0.10 [95% CI, 0.07-0.14] to 0.16 [95% CI, 0.12-0.19]), the reverse association was not significant. In the final model that included all 3 constructs, the associations were attenuated but remained significant over time. Conclusions and Relevance These results suggest that future studies should investigate whether implementing sleep problem intervention decreases the occurrence of both externalizing and internalizing difficulties. Interventions targeting externalizing, but not internalizing, difficulties may benefit childhood sleep.
