Dr Sarah Rose, Senior Lecturer at Staffordshire University, writes for The Conversation

Get children more active. That’s the aim of the World Health Organisation’s new guidelines on physical activity, sedentary behaviour and sleep for children under five years of age. The guidelines make specific recommendations about the amount of sleep, physical activity and screen time children should have each day.

For screen time, the guidelines state that children under two years old should get no screen time and children aged two to five should get no more than an hour a day.

While childhood obesity is a global crisis, cuts lives short and has significant economic costs the WHO guidelines on screen time are oversimplified.

The main evidence the WHO guidelines draw on is a 2017 review of evidence looking at the relationship between sedentary behaviour and health in children under the age of five. Of the 96 papers identified in this review, 54 focused on the association between obesity and screen use. Of these, the authors of the report rate all but one as “very low-quality evidence”, using the GRADE framework – a widely used tool for rating medical evidence.

There are two main reasons for the evidence being rated as low quality. First, almost all the studies are observational, meaning they can’t show cause and effect, only associations between screen time and obesity. Second, the findings are not consistent. Of the 54 studies, 25 found no association between screen time and obesity, 13 found that higher amounts of screen time were related to higher levels obesity and 16 found a mixture of results, depending on the type of screen time and obesity measure used.

Read the full article on The Conversation