Physical and psychological effects of smart devices on children: A systematic review and meta-analysis (Preprint)

BACKGROUND Smart devices such as smartphones, tablets, and televisions are widely used by children and adolescents for educational, recreational, and social purposes. While these technologies offer potential benefits, increasing concerns have emerged regarding their impact on physical health, psychological well-being, and developmental outcomes. Existing studies often focus on isolated outcomes or specific age groups, limiting understanding of the broader and long-term consequences of smart device use during childhood and adolescence. OBJECTIVE This systematic review and meta-analysis aimed to synthesize evidence from randomized controlled trials (RCTs) and cohort studies on the physical and psychological effects of smart device use among children and adolescents aged 1–18 years. METHODS This review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and was prospectively registered in the International Prospective Register of Systematic Reviews (PROSPERO) (CRD420250615063). A comprehensive search of PubMed, Web of Science, ScienceDirect, Google Scholar, Arab World Research Source, Directory of Open Access Journals, OpenAIRE, and Emerald Insight identified studies published between January 2000 and December 2024. Eligible studies included randomized controlled trials and cohort studies evaluating physical (eg, vision, sleep, obesity) and psychological or developmental outcomes (eg, mental health, behavior, cognition) associated with smart device use among children and adolescents. Risk of bias was assessed using the Cochrane Risk of Bias 2 tool for randomized trials and the ROBINS-I tool for non-randomized studies. Quantitative synthesis was conducted when studies were sufficiently comparable, and thematic analysis was used for psychological outcomes. RESULTS A total of 23 studies, including 3 randomized controlled trials and 20 cohort or longitudinal studies, were included, with sample sizes ranging from 67 to over 1 million participants across diverse age groups. Higher levels of smart device use—commonly exceeding 1–3 hours per day or averaging up to 7 hours daily—were consistently associated with adverse physical outcomes, including shorter sleep duration, visual strain, and increased risk of obesity. Psychological and behavioral effects included increased anxiety, depressive symptoms, aggression, reduced psychological well-being, and body dissatisfaction, particularly in relation to social media use. Several longitudinal studies reported delays in communication and motor development among younger children with higher exposure. In contrast, randomized controlled trials demonstrated improvements in mental health outcomes following reductions in screen time. Risk of bias was generally low among randomized trials and moderate among cohort studies, primarily due to confounding and reliance on self-reported exposure measures. CONCLUSIONS Evidence from high-quality randomized and longitudinal studies indicates that excessive smart device use among children and adolescents is associated with adverse physical, psychological, and developmental outcomes, while reductions in screen time may confer mental health benefits. These findings underscore the need for evidence-based guidelines that address both the duration and nature of smart device use. Future research should focus on defining optimal exposure thresholds, differentiating effects by content type, and evaluating long-term developmental consequences. CLINICALTRIAL PROSPERO CRD420250615063