The association between mobile devices use and behavior problems among fourth grade children in Japan

Aim Previous studies showed mixed evidence on the association between duration of mobile devices usage and behavior problems among children. We aimed to examine this association using a large population‐based sample of fourth grade children (i.e. aged 9–10 years old), stratified by gender. Methods Questionnaires with anonymous unique identifiers were distributed to 4th grade students (aged 9–10 years old) at all public schools in Adachi City, Tokyo (n = 4,105). Duration of mobile devices usage was self‐reported, and behavior problems were assessed by the Strengths and Difficulties Questionnaire by caregivers. Multiple regression analyses were performed, adjusting for potential confounders such as socioeconomic status, family social capital, and number of friends. Results Among boys, U‐shape association was found between duration of mobile devices usage and behavior problems; boys with usage time of less than 1 h showed 0.88 [95% confidence interval (CI) −1.50 to −0.27] point lower total difficulty score in comparison with boys who do not use mobile devices, and total difficulty score among boys with usage time of 1 h or more was not different with non‐users. Among girls, dose–response positive association was found between duration of mobile devices usage and total difficulty score (P for trend: