A child using a tablet

Too much screen time for young children may lead to unhealthy behaviours growing up

Screen viewing is increasingly prevalent but excessive screen time in childhood has been linked to a range of health problems, including increased risk of obesity and reduced cognitive development.

A study found that toddlers who spend more than three hours a day looking at a screen are more likely to be less physically active by the time they reach kindergarten-age.

The researchers suggest that limiting the exposure of young children to screens (such as TVs, computers and handheld devices) to one hour a day may promote healthier behaviours later in life. This is in line with recommendations by the World Health Organization (WHO) to limit screen time to an hour or less per day among two- to five-year-olds.

Published in The Lancet Child & Adolescent Health, the study used data of over 500 children from the Growing up towards Healthy Outcomes (GUSTO) cohort.

Parents were asked to report how much time their children spent on average either watching or playing video games on TV, using a computer, or using a handheld device, such as mobile phone or tablet. These screen habits were recorded when the children were aged two, and again at age three. At age five, the children wore an activity tracker continuously for seven days to monitor their sleep, sedentary behaviour, light physical activity, and moderate-to-vigorous physical activity (MVPA).

On average, children in the study spent 2.5 hours a day on screens. Television was the most commonly used device and was associated with the longest viewing time. One-third of screen time was on handheld devices. Only a small proportion met WHO’s recommendations.

Children who clocked more than three hours of screen time a day spent on average 30 minutes less doing light physical activity, 10 minutes less doing MVPA and 40 minutes more sitting down, as compared with those who used screens for less than an hour a day. Similar effects were observed regardless of screen type.

“Our study provides scientific evidence that screen viewing displaces time that is otherwise spent on more positive activities, such as physical activity,” said Associate Professor Falk Müller-Riemenschneider, who led the study. A/Prof Falk leads the Physical Activity and Nutrition Determinants in Asia (PANDA) programme at the School.

The authors noted some limitations, including that parents may be biased in their reporting of their child’s screen use, and that the study did not control for other health behaviours (such as diet, sleep and physical activity) or environmental factors (such as time in childcare) because there was limited information about these available.

The authors also advised caution when generalising from their results as the families involved in the study were not representative of the entire Singapore population.

However, they argue that the negative impact of early-life screen time on movement behaviours in later childhood highlights the importance of strategies to limit screen use during the early years.

PhD student Ms Sophie Chen Bozhi, who co-authored the study, said that the study addresses an important research gap and strengthens existing associations between screen time and children’s health.

“Our findings support public health efforts to reduce screen viewing time in young children and suggest further research into the long term effects of screen viewing on movement behaviours is needed,” she said.

The study is available with limited access here: Associations between early-life screen viewing and 24 hour movement behaviours: findings from a longitudinal birth cohort study

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