Role of Sleep and White Matter in the Link Between Screen Time and Depression in Childhood and Early Adolescence

With the widespread adoption of screen-based devices among adolescents, there is growing concern that more screen time could contribute to mental health problems such as depression. It is thus critical to identify potential mediating factors that could help explain this potential risk relationship. Recent evidence indicates that more screen time could impact sleep duration and brain structural connectivity (ie, white matter organization), which are critical for emotional health. Notably, sleep duration is a modifiable behavior that health care providers can easily target. To identify the association between screen time during late childhood and depressive symptoms in early adolescence, and to investigate whether these associations are mediated by sleep duration and white matter organization. This prospective study was conducted from January 2024 to June 2024. Data from the Adolescent Behavior Cognitive Development (ABCD) Study were used to identify clinical and neuroimaging characteristics of participants at late childhood (T1; defined as aged 9-10 years) and early adolescence (T2; defined as age 11-13 years). Children and their parent/caregiver were recruited across 21 US cities. Participants with no past/current psychiatric disorders at T1 were selected for analyses. Initial analyses were conducted in 2024 and finalized in February 2025. Outcomes included screen time assessed using a self-report questionnaire, sleep duration assessed using the Munich Chronotype Questionnaire, and depressive symptoms characterized using the Child Behavior Checklist. Neurite orientation dispersion and density imaging and a tract profile approach were used to characterize the orientation dispersion index of 3 white matter tracts that are known to be implicated with depression: cingulum bundle, forceps minor, and uncinate fasciculus. Analyses included 976 participants (460 children [47.1%] were female, mean [SD] age was 9.9 [0.6] years at T1 and 11.9 [0.6] years at T2). Each additional hour of daily screen time at T1 was associated with a 0.12-point (95% CI, 0.04-0.20; P = .008) increase in Child Behavior Checklist depressive score at T2. Shorter sleep duration and worse cingulum bundle organization (greater orientation dispersion index) at T2 mediated 36.4% (95% CI, 18.2%-63.6%) of the association between more screen time and more depressive symptoms. Results of this study show that more screen time in late childhood was associated with more depressive symptoms, potentially due to shorter sleep and worse white matter organization during early adolescence. These findings emphasize the importance of promoting healthy habits and balancing screen time with adequate sleep.