JMIR Publications

ABSTRACT

Background:

With rising digital media use among young children, concerns have grown regarding its impact on early socioemotional development. However, evidence regarding the dose-response relationship between digital screen time and children's mental health, as well as the potential indirect role of family factors, remains limited.

Objective:

To explore the nonlinear association between screen time and mental health outcomes in preschool children, identify a potential threshold, and examine the indirect role of parental discipline in this relationship.

Methods:

This cross-sectional study included 21,366 parent-child dyads from Western China. Children’s mental health (total difficulties, externalizing, internalizing) was assessed with the Strengths and Difficulties Questionnaire. Parents reported daily screen time (weekday/weekend). Generalized additive models (GAM) and piecewise logistic regression were used to identify nonlinear patterns and thresholds. Mediation analysis quantified the indirect role of parental discipline and moderation analysis is used to examine interaction effects.

Results:

A significant nonlinear association was found, with a threshold at 70.71 minutes/day. Weekday screen time showed a stronger dose-response pattern than weekend time. Significant interactions were observed for number of children and household registration. Parental discipline accounted for 20–24% of the associations. Multiple sensitivity analyses confirmed the robustness of the findings.

Conclusions:

Daily digital screen time has a non-linear threshold effect on preschool children’s mental health. Reducing daily screen time, especially weekday screen time, and improving parental discipline may effectively promote early mental health in preschool children. These findings support evidence‑based digital screen time limits and highlight modifiable targets for digital parenting interventions.