Children who spend hours watching television or playing video games do worse at school, scientists claim.
In the largest study of its kind, the habits of almost half a million children across the globe were analysed.
Generally, time spent on screens, including mobile phones, did not affect academic performance.
However, children who chose to watch the TV or play video games in the majority of their free time did suffer worse grades at school, the study found.
The study comes as within the next year UK government guidelines are expected to set limits for children’s screen time in a bid to protect their mental health.
Children who spend hours watching television or playing video games do worse at school, a study of almost half a million young people found
Lead author Dr Mireia Adelantado-Renau, of University Jaume I in Castellon, Spain, said: ‘Each screen-based activity should be analysed individually for its association with academic performance.
‘Education and public health professionals should consider supervision and reduction to improve the academic performance of children and adolescents exposed to these activities.’
The research, published in JAMA Pediatrics, reviewed 58 studies from 23 countries involving 480,000 youngsters under the age of 18.
The team also pooled data from 30 of those studies, including 106,000 participants, which compared screen media use and academic performance.
Academic performance was measured by analysing their language and mathematics ability and composite scores.
A composite score is an average of four test scores in English, mathematics, reading, and science, ranging from one to 36.
Screen time included internet surfing, mobile phone use, television viewing and video game playing.
Television and video games were linked to lower composite scores, while television individually appeared to negatively affect language and mathematics skills.
Further analysis suggested these screen-based activities have a greater effect on adolescents than children.
Television viewing may reduce how much youngsters use their brain, compared to if they were exercising, the researchers said.
‘In addition, excessive television viewing time among children has been shown to decrease attention and cognitive functioning and to increase behavioral problems and unhealthy eating habits, which may also impair academic outcomes,’ the authors said.
Video games, on the other hand, may trigger psychological and behavioural problems, implicating a child’s schooling.
Dr Adelantado-Renau said the research was important ‘given the increasing time spent on screen-based activities among children and adolescents’.
In February this year, the UK’s medical officers said mobile phones should be banned from the dinner table and bedtimes.
Dame Sally Davies said a code of conduct was definitely needed to keep children safe in the wake of Molly Russell’s suicide.
Links were made between the teenager’s death and her exposure to harmful material on Instagram.
The findings of this study did not support previous studies which have found overall time spent on screens negatively effects grades or a child’s development.
Canadian researchers found that adolescents who spent more than seven hours per day on overall screen media were 40 per cent less likely to achieve high academic performance.
And toddlers who use screens for more than two hours a day are seven times more likely to develop ADHD, according to scientists at University of Alberta.
The screen time has a ‘significant impact’ on the child’s development, the researchers said. Both studies were published in the journal PLOS ONE.
HOW COULD TOO MUCH TIME STARING AT SCREENS AFFECT CHILDREN?
Research has shown spending too much time looking at screens – smartphones, tablets, computers and televisions, for example – can be damaging to children’s intelligence, sleep, mental health and vision.
A 2018 study by the CHEO Research Institute in Ottawa found eight to 11-year-olds performed five per cent worse on brain power tests than their peers if they spent two hours per day looking at screens.
This, they suggested, may be because looking at screens isn’t as stimulating as reading, and could interfere with vital sleep.
Disturbed sleep was also the focus of a warning from the UK’s Royal College of Paediatrics and Child Health earlier this year, when it recommended children don’t use screens before bed.
The RCPCH said high levels of screen time are linked to a less healthy diet, a sedentary lifestyle and poorer mental health.
Dr Max Davie, a health officer said: ‘Parents need to get control of their own screen time if they are going to get control of the family’s screen time. It’s much easier to be authoritative if you practise what you preach.’
Dr Langis Michaud, a professor of optometry at the University of Montreal, wrote in The Conversation in February: ‘A rapid increase in visual problems has been noted since the introduction of the smartphone in 2007.
‘While the device itself does not emit harmful radiation, it requires the user to read its screen at a distance of 20 cm rather than the normal distance of 45cm to 50cm.
‘It has been suggested that this close distance boosts the risk of developing myopia by eight times, especially if both parents are myopic.’