Effects of screen time on the development of children under 9 years old: a systematic review

Importance: This systematic review could serve as a comprehensive synthesis that would benefit parents, educators, therapists, policymakers, and researchers in identifying the advantages and disadvantages of screen time (ST) on key developmental outcomes of children, specifically socio-emotional functions (SEF), executive functions (EF), cognition, language, and motor skills. Objectives: To comprehensively review the current state of literature to examine the association of the effects of ST on several developmental outcomes; to analyze the methodological quality of included studies to facilitate appraisal of evidence strength. Methods: A systematic search across EBSCO, ScienceDirect, PubMed Central, and Scopus was accomplished to identify both peer-reviewed and gray literature that reported on the association between ST and varying developmental outcomes. A chronological restriction (studies published between January 2000 and March 2020) was implemented. Inclusion criteria were studies that had participants from 0 to 9 years old, measured duration of ST, explored the effects of any of the aforementioned outcomes, and were observational studies by design (i.e., cross-sectional, cohort, case-control). Meta-analysis was not done due to clinical heterogeneity. Results: The narrative synthesis included 85 studies (from 16 countries) which had cross-sectional (n = 47), cohort (n = 36), and case-control (n = 2) designs. The majority of the studies had good (n = 16) to fair (n = 59) methodological quality. ST was generally associated with poorer SEF, EF, cognitive and motor development. Less than half of language studies supported the negative effect of ST. However, its positive effects were observed in certain conditions: (1) implementation of time limit on ST use, (2) parental co-viewing, and (3) exposure to educational content. Conclusion and relevance: The findings support the reduction of ST in children and further substantiate the American Academy of Pediatrics recommendations. The results also highlight the roles of parents and caregivers as it shows that digital media could be used as a tool to improve the development of children, given that certain conditions are met. Further research could be done on the positive effects of ST given the aforementioned conditions and the appropriate dosage of ST use.