By the time they are teenagers, more than two-thirds of young people are not doing enough physical activity. Teenagers spend an average of eight hours every day sitting, with 11 to 15-year-olds watching nearly three hours of television. Most of us are well aware that such behaviour risks damaging their physical health, but there’s an additional problem. I have been involved in a new piece of research which suggests that too much screen time is also harming grades.
We measured the physical activity and sitting time of 845 teenagers at 14.5 years old, using a sensor that measures movement and heart rate. We asked how much time they spent watching TV, playing computer games, going online, doing homework and reading. And at the end of year 11, when these students were 16-years-old, we collected their GCSE results.
We found that teenagers with higher screen time had lower GCSE grades, even when we took account of differences in homework and reading. Television, computer games and internet use were all associated with poorer academic performance, but TV viewing was the most detrimental. For every hour that someone watched per day, they showed a drop of nine GCSE points in total – the equivalent of two whole grades in one subject (or for example, one grade in each of two subjects). Two extra hours was associated with 18 fewer points.
Although we did not find that more physical activity was associated with higher grades, as some other studies have suggested, it was not detrimental to academic performance either. It’s important that this message isn’t lost among the findings about screen time: schools are under so much pressure to improve exam results that many don’t prioritise PE and other opportunities for physical activity for fear that they interfere with academic achievement.
The Case for 60 A Day
The wider picture is that most teenagers are failing to meet the recommendations of doing at least 60 minutes of moderate or vigorous physical activity each day (activity that makes you sweat and breathe heavily). This needs to change if we are to develop a more rounded approach to our children’s education. Behaviours developed in the teenage years are likely to persist into adulthood, and we need to take every opportunity to improve the nation’s health by tackling high levels of physical inactivity across the population.
