Sleep, screen time and behaviour problems in preschool children: an actigraphy study.

Inadequate sleep and excessive exposure to media screens have both been linked to poorer mental health in youth. However, the ways in which these interact to predict behaviour problems have yet to be examined using objective sleep measurement. The lack of objective evidence for these relationships in young children has recently been defined by the World Health Organization (2019) as a gap in the field. We thus aimed to test the interacting effects of screen exposure and objectively measured sleep on behaviour problems in the preschool age. A total of 145 children aged 3-to-6-years participated in this cross-sectional study. Sleep was assessed objectively using actigraphy for 1-week, and subjectively using parent-reported daily sleep diaries. Parents reported the child's daily duration of screen exposure, and completed the Strengths and Difficulties Questionnaire. Results showed that actigraphic sleep duration, timing and efficiency were associated with screen exposure. The link between screen time and behaviour problems was moderated by sleep duration, as it was significant only for children with sleep duration of 9.88 h or less per night. Sleep duration also moderated the relation between screen time and externalizing-but not internalizing-problems. Hence, the combination of increased screen exposure and decreased sleep duration may be particularly adverse for child mental health. While these key relationships should be further examined in longitudinal and experimental investigations, our findings shed light on their complexity, underscoring the importance of the moderating role of sleep.