Just 90 minutes of screen time a day is enough to affect childrens’ reading and writing ability — and even increase the risk of behavioural problems, a study has revealed.

Researchers at the University of Canterbury in New Zealand tracked more than 6,000 two to eight year-olds to investigate the consequences of looking at screens for more than an hour daily.

This is the maximum amount recommended by health chiefs — however most children in the UK spend more than two hours a day glued to devices.

In fact, one in five already own a smartphone by the age of two, according to the online regulator Ofcom, the Telegraph reported. 

The peer-reviewed research, published in the journal Developmental Psychology, collected data through interviews with parents and behavioral assessments of children when they were two, four and a half, and eight years old.

Parents were asked how long their children spent doing ‘unproductive’ activities using screens — like watching television — and the amount of time spent using devices for homework.

Researchers found that children aged four and eight and a half, who spent more than 1.5 hours in front of a screen, suffered educationally, regardless of the nature of the activity.

Just 90 minutes of screen time a day is enough to give children weaker language skills and behavioural problems, researchers found

These children had below average vocabulary, communication, writing, numeracy, and letter fluency. 

Plus, they were more likely to play alone and less liked by other children. 

The longer the screen time the worse off they were, with children who spend longer than 2.5 hours a day even more likely to experience language and behaviour problems. 

On the other hand, children with less than an hour a day of screen time had higher education levels, such as better language skills and were more sociable.

The study authors suggested that the impact of too much screen time was significant enough to mean the child was more likely to be in the bottom third of their class at school. 

Teachers have reported seeing more children coming into school at age five with lower-than-average language and social skills, which researchers believe is the result of too much screen time. 

‘Screen time during early childhood is predictive of the skills that children have on arrival to school, and the dramatic rise in screen use over recent years may partially explain why school readiness has been declining over recent years,’ researchers said.  

The impact on education is thought to be worse than any health risks of being sedentary as a result of their screen time, which could cause children to be obese or be frequently ill. 

Experts have long raised the alarm over the influence of screen time on child development.

One 2024 Australian study found two-year-olds who spend large portions of time looking at screens were more likely to show autism-like symptoms by the age of 12. 

But the researchers, who tracked more than 5,000 kids, did acknowledge the paper was merely observational and could not prove causality.

Other scientists also urged the public not to panic and said the study proves ‘there is no actual evidence’ linking screen time with autism.

Guidelines set by World Health Organisation (WHO) recommends children under the age of two should have no screen time at all. 

Those between two and five should only should spend less than one hour a day at a screen.

Yet, in the UK, neither the NHS nor the National Institute for Health and Care Excellence (NICE) have any detailed guidance for screen time among babies and toddlers.

NICE recommend an upper limit of two hours per day for all children.

The UK’s Chief Medical Officer also suggests a ‘precautionary approach’ to using screen devices.