According to the first global review of research, screen time increased for primary school children by an average of 20 minutes a day.

Researchers said that the rise in screen time was associated with poorer diet in children, poor eye health, and worse mental health.

There are calls for action to curb the harmful impact on the health of millions of kids.

There was a daily increase in screen time for people between the ages of six and 10. The global analysis of studies showed that there had been significant increases in all age groups.

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The reviewers found that all age groups increased their screen time. The largest increases were reported by primary-aged children.

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Researchers found that more time spent looking at screens such as the television or computer was associated with a negative impact on health.

The biggest increases were recorded by primary school children. The next two groups were adults with 58 minutes and adolescents with 55 minutes. There was a 35 minute increase in screen time for children under five.

Prof Shahina Pardhan is the senior author and director of the Vision and Eye Research Institute at Anglia Ruskin University.

She said: "Bringing together numerous studies gives us a much more accurate picture of screen time among the population and its associated health consequences." There are differences between the research looked at.

The overall picture shows that screen time should be reduced in order to avoid negative outcomes. There are effects on mental health and eye health.

The risk of increased screen time is mitigated by the promotion of non-sedentary activities.

Researchers looked at studies from the UK, US, Australia, France, and Israel. The total sample size of more than 200,000 people was covered in the analysis.

Leisure screen time, or screen time not related to work or study, increased in all age groups. The biggest increase was seen by children between the ages of six and ten.

The research found links between screen time and negative outcomes for adults. There were adverse effects on diet, eye health and mental health, as well as on general health, including fatigue, decreased physical activity and weight gain.