Children under the age of three should not watch TV or sit playing games on a tablet, while those aged three and four should not have more than an hour of screen time a day, according to disputed guidelines on physical activity and sleep by the World Health Organization.

Face-to-face interaction with parents or carers is essential for small children’s development, the WHO says. Reading to them, playing games and physical activity are considered far more important than screen time. Set bedtimes are also encouraged.

But UK experts claimed the guidelines were based on poor evidence and failed to recognise that not all screen time was bad for children.

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The Royal College of Paediatrics and Child Health said the advice could dismay families raising children in cramped housing without outdoor space to play, adding that every child had unique sleep requirements. “Without the right support in place, striving for the perfect could become the enemy of the good,” said Dr Max Davie, its officer for health improvement.

Others accused the WHO group behind the guidelines of making sweeping recommendations based on little evidence.

Dr Tim Smith, a reader in cognitive psychology at Birkbeck, University of London, said: “In recent months UK parents of 0- to five-year-olds and early-years practitioners have been bombarded with conflicting recommendations and guidelines about how and whether they should be managing their children’s screen time and sedentary behaviour … The release of new WHO guidelines does not help to clarify the situation.”

The guidelines suggest children over one and under five should be physically active, spending at least three hours in play. They should not be restrained in a pushchair or carry seat for more than an hour.

The youngest children – under one year and not yet mobile – should have at least half an hour a day of “tummy time”, lying on the floor. Under-fives should not stay up late with their parents; they should have a lot of good quality sleep with regular bedtimes and waking-up times.

The group was asked to investigate and produce guidelines by the WHO’s commission on ending childhood obesity, amid concerns about a global rise in children who are overweight and obese, which threatens their future health.

In 2016, 41 million infants and young children were overweight or obese, it said. There has been a tenfold increase in the number of obese children and adolescents in the past 40 years to 124 million – nearly one in five. Inactivity, worsened by sedentary pursuits such as watching TV and playing computer games, has played a part and often starts early.

“There is no denying that screens are part of the modern era. It is how we interact that matters,” said Dr Juana Willumsen, one of the authors. But the group found no advantage to introducing them under the age of three, and not just because of concerns over reduced physical activity.

“Social and cognitive skills are better developed with another person rather than a screen,” she said. “Interactive play with care-givers is absolutely vital for child development, particularly in these early years.”

Children under one should sleep for 14-17 hours a day. One- to two-year-olds should have 11-14 hours of good quality sleep, while those aged three to four should get 10-13 hours. This means set bedtimes are recommended. “For children, it is regularity that is important,” Willumsen said.

Under-ones should have at least 30 minutes of physical activity a day and other under-fives should have 180 minutes, the guidelines say.

“We don’t have global estimates on physical activity in young children. It varies widely. One of the few studies that does exist ranges from 20% to 75% not meeting current recommendations,” Willumsen said. “The important thing is trying to establish these habits in early life.”

Davie welcomed the WHO’s focus on such an important health issue, but said: “While it is important for children to be as active as possible, the barriers are more frequently to do with housing, work patterns, family stress, and lack of access to play spaces rather than actively choosing to be sedentary.

“Likewise, the restricted screen-time limits suggested by the WHO do not seem proportionate to the potential harm. Our research has shown that currently there is not strong enough evidence to support the setting of screen time limits, and that screen use should be considered alongside a range of activities to assess its impact. Also, it is difficult to see how a household with mixed-age children can shield a baby from any screen exposure at all, as is recommended.

“Similarly, comparing an individual child’s sleep to the quantities recommended by the WHO should be done with caution. All children have unique needs – some sleep relatively little with no ill-effects, while others need much more. Individual assessment is paramount.”

Prof Kevin McConway, emeritus professor of applied statistics at the Open University, said there were “some surprising features” to the guidance, though he was sympathetic to the expert group because little good-quality evidence for best practice exists. Studies of physical activity were very hard to do in small children.

“The new report acknowledges that the evidence is poor overall, and makes many recommendations for research to fill the gaps,” he said. “But in light of that, should the authors really be making such strong recommendations, which appear in many cases to be based largely on consensus of expert judgment? Would it have been better to be less precise, rather than attaching such detailed numbers and times without decent evidence to support them?”