Screen time above a 2-hour threshold at 5 years of age is associated with an increased risk of clinically relevant externalizing problems such as inattention, according to a study published April 17 in the open-access journal PLOS ONE by Piush Mandhane of the University of Alberta and colleagues.

Increased screen time in children has been associated with unhealthy dietary patterns, poor sleep quality, cardiovascular disease, and obesity. There has been a significant increase in screen options in recent years, from device choices to streaming content, with rising concern that screen time may have negative consequences for mental health. But there is relatively little research examining associations between screen-time exposure and behavioral development in the preschool years. Most studies have focused on school-aged children or have only considered traditional screen sources such as television viewing. To address this gap in knowledge, Mandhane and colleagues analyzed data from the population-based Canadian Healthy Infant Longitudinal Development (CHILD) birth cohort study to determine associations between screen time and behavioral outcomes at age 5 years.

Parents reported their child’s total screen time including gaming and mobile devices and completed the Child Behavior Checklist when the child was 5 years old. Mean screen time was 1.4 hours per day at 5 years and 1.5 hours per day at 3 years. Compared to children with less than 30 minutes per day of screen time, the 13.7% who watched more than 2 hours each day were five times more likely to report clinically significant externalizing problems, and were 5.9 times more likely to report clinically significant inattention problems. Moreover, children with more than 2 hours of screen time per day had a 7.7-fold increased risk of meeting criteria for attention-deficit/hyperactivity disorder. According to the authors, the findings indicate that preschool may be a critical period for educating parents and families about limiting screen time and encouraging physical activity.

The authors add, “How much is too much screen time for children? Using data from a large Canadian cohort, we found that children with more than 2 hours of screen time per day had significantly more behavior problems at 5years of age. Interestingly, the more time children spent doing organized sports, the less likely they were to exhibit behavioral problems. Taken together, our results support an active beginning for children with screen time replaced by more organized sports.”