Less than 10% of British teenagers meet the recommended guidelines for sleep, exercise and screen time, research has revealed.
According to 24-hour movement guidelines developed by Canadian researchers, children aged between five and 17 should spend an hour a day doing moderate to vigorous exercise, no more than two hours a day in front of a screen, and get at least eight hours’ sleep a night.
But a new study suggests only 9.7% of 14-year-olds in the UK manage all three recommendations, with more than three-quarters of teenagers spending more than two hours a day interacting with screens.
“Screen time was the main driver of not meeting all three recommendations,” the authors noted.
However the idea of screen time is controversial: many experts say there is not enough evidence to recommend a threshold for children, with recent guidelines from the Royal College of Paediatrics and Child Health stating: “We are unable to recommend a cutoff for children’s screen time overall.” Instead they recommend parents focus on whether screen use is interfering with other activities such as sleep and family time.
Other research supports the idea that it is not how much screen time that matters per se, but more nuanced considerations, such as when and how screens are used.
Mark Hamer, a professor of sport and exercise medicine at University College London and a co-author of the new research, said evidence suggested levels of physical activity were the most important of the three behaviours for health. But, he added, boosting exercise time involved looking at how time was spent on other activities.
He said: “In essence these behaviours are heavily interrelated as the 24-hour day is finite and increasing time in one behaviour tends to decrease time in another, [for example deciding] to play football instead of watching TV.”
The latest study, published in the journal Jama Pediatrics, is based on data collected between January 2015 and March 2016 from 14-year-olds in the UK as part of a wider research endeavour.
Each participant self-reported their average daily screen time – including TV, tablet and computer use – and their bedtime and waking times on an average school night. Levels of exercise were monitored through an activity tracker worn on both a weekday and a weekend day. Other data was gathered through questionnaires and measurements. In total, data from almost 4,000 teens was analysed.
The results reveal that almost 90% of participants reported sleeping for more than eight hours on a school night, but only 23% said they spent two hours or less a day interacting with screens. Activity tracker data revealed that about 41% of teenagers met the recommended level of moderate to vigorous physical activity. Only 9.7% of participants met recommendations for all three behaviours.
The team found that teenagers with symptoms of depression were less likely to meet all three recommendations. Overweight girls and obese boys were also less likely to meet all three.
However, the study has limitations including that both screen time and sleep duration were based on self-report, which can be unreliable.
Prof Russell Viner, the president of the Royal College of Paediatrics and Child Health, and who was not involved in the research, said the study only looked at behaviour at one point in time, and so could not unpick cause and effect – for example around depression. Furthermore, UK guidelines recommend that teenagers get at least 10 hours’ sleep a night – more than the Canadian guidelines suggest.
He said: “Other research has suggested that screen use might impact upon mental health and wellbeing through interfering with healthy activities such as physical activity and sleep. Whilst this study can’t prove such a link, it confirms that we need to focus on ensuring young people get enough sleep and physical activity during the day.”
