It doesn’t matter whether kids spend time in front of a TV or in front of a computer. Too much screen time can put children behind in school. Either way, an Australian study found that more screen time was associated with poorer academic performance.

Both types of screen time set the children behind by about four months, according to their test scores.

Kids who used a computer for more than an hour a day in grade three had lower math scores when tested in grade five.

Screen use has been on the rise for years and has been blamed for a host of ills, but actually measuring those problems is tricky. To determine how screen time might be affecting academic performance, researchers compared the screen use of over 1,200 third-graders with their scores on national tests as fifth graders two years later.

Children who watched more than two hours of TV a day as third graders had a lower reading score than other children, when tested during grade five. Kids who used a computer for more than an hour a day in grade three had lower math scores when tested in grade five. Both test score differences indicated that these children were about four months behind the other children in the study.

Parents reported the amount of time children spent watching TV, using a computer and playing video games. The researchers, from the Universities of Melbourne and Helsinki and other institutions, took into account several factors, including age, sex, economic status and baseline test scores when analyzing the fifth-grade test results. Somewhat surprisingly, video game use appeared to have no effect on test scores.

Smartphone screen use was not tested. Only about one in four 8- to 11-year-old Australian children own their own phone, according to a national survey cited by the authors.

Months of sheltering at home during the COVID-19 pandemic has likely increased kids’ screen time even more. Now as children start going back to school, this study suggests that the effects of so much time in front of a screen may well show up as poorer academic performance.

Media use generally increases as children enter adolescence, so parents may want to intervene sooner rather than later. Parents looking for ways to set limits on their children's screen time can find suggestions on how to do so here.

This is the first large study to look at how primary school children’s screen use affects academic performance over time, according to the authors. The findings suggest that if children spent a bit less time in front of the TV or computer, their school work would likely improve.

The study is published in PLOS ONE.