Children who use screen-based media devices at bedtime, such as smartphones and tablets, are much more likely to get poor sleep, which can have major consequences for their overall health, a new study has found.

Welsh researchers carried out a review of 20 studies involving more than 125,000 children. They found that those who used screen-based media devices at bedtime had more than double the risk of experiencing inadequate sleep duration - in other words, not getting enough sleep.

These children were also more likely to experience poorer quality sleep and to be affected by daytime sleepiness.

"Our study is the first to consolidate results across existing research and provides further proof of the detrimental effect of media devices on both sleep duration and quality," commented Dr Ben Carter of the University of Cardiff.

He noted that while sleep is essential, it is often an ‘undervalued' part of a child's development. A regular lack of sleep, he said, can cause a range of health problems, including sedentary behaviour, obesity, poor diet, reduced immunity and mental health issues.

Current research suggests that as many as seven in 10 children and almost nine in 10 teenagers have at least one media device in their bedroom and most of these are used near or at bedtime.

These devices are thought to negatively impact on sleep in a number of ways, including delaying or disrupting sleep, keeping the brain psychologically stimulated when it should be trying to relax and adversely affecting the circadian rhythm (body clock).

"With the ever growing popularity of portable media devices, such as smartphones and tablets, the problem of poor sleep amongst children is set to get worse. Our findings suggest that an integrated approach involving parents, teachers and healthcare professionals is necessary to improve sleep habits near bedtime," Dr Carter said

Details of these findings are published in the journal, JAMA Pediatrics.