Screen time during the Covid pandemic increased the most among primary schoolchildren, by an extra hour and 20 minutes a day on average, according to the first global review of research.
The sharp rise in screen time was associated with poorer diets in children, poor eye health, deteriorating mental health including anxiety, and behavioural problems such as aggression, irritability and increased frequency of temper tantrums, researchers said.
The findings have prompted calls for action to curb the harmful impact on the health of millions of children.
The biggest daily increase in screen time was among those aged between six and 10. But "significant" increases were seen among all age groups including adults, according to Anglia Ruskin University, which led the global analysis of studies.
"This review found that all age groups increased their total screen time," the researchers wrote in eClinicalMedicine, which is part of the Lancet Discovery Science journal. "Primary-aged children reported largest increases, followed by adults, adolescents, and young children. Leisure screen time also increased in all age groups, with primary-aged children reporting the largest increases, followed by adults, young children and adolescents."
Researchers found that overall more time spent looking at screens such as the television or computer was associated with a negative impact on diet, sleep, mental health and eye health.
Primary schoolchildren recorded the largest increases, of 83 minutes a day. Next it was adults, with 58 minutes, and adolescents (aged 11 to 17), with 55 minutes. Children under five had the lowest increase in screen time, going up by 35 minutes, although even this increase is not insignificant.
"This study is the first of its kind to look systematically at peer-reviewed research papers on increases in screen time during the pandemic and its impact," said Prof Shahina Pardhan, the senior author and director of the Vision and Eye Research Institute at Anglia Ruskin University.
She said: "By bringing together numerous studies, we get a much more accurate picture of screen time among the population and its associated health repercussions. As with any study of this type, there are degrees of variability between the research looked at.
"However, the overall picture provides clear evidence that screen time should be reduced wherever possible to minimise potential negative outcomes. These include adverse dietary behaviours, sleep, mental health and eye health effects.
"It is also important that non-sedentary activities are promoted to mitigate the risks of increased screen time."
Researchers analysed 89 studies from countries including the UK, US, Australia, France, Chile and Israel. The analysis focused on increases in screen time before and during the pandemic, in detail, covering a total sample size of more than 200,000 people.
The study also looked at the types of screen time, and found that leisure screen time, or screen time not related to work or study, also increased in all age groups. Children between the ages of six and 10 once again showed the biggest increase.
As well as harmful effects on children, the research further identified links between more screen time and negative outcomes for adults. These included adverse effects on diet, eye health and mental health, such as anxiety, depression and loneliness, and on general health, including fatigue, decreased physical activity and weight gain.
