Smart phones in bed linked to insomnia and poor quality sleep

With their brains, sleep patterns and even eyes still developing, children and adolescents are particularly vulnerable to the sleep-disrupting effects of screen time, according to a review of the literature published in the journal Pediatrics.

The researchers reviewed more than 60 studies on children's screen time in front of TVs, computers, tablets and smart phones. More than 90 per cent found it led to delayed bedtimes, fewer hours of sleep and worse sleep quality, with the evidence suggesting children's immature eyes may be to blame.

Lead author Dr Monique LeBourgeois, from the University of Colorado at Boulder, said: "Light is our brain clock's primary timekeeper. We know younger individuals have larger pupils, and their lenses are more transparent, so their exposure and sensitivity to that light is even greater than in older individuals."

Data from US population-based studies show that about 30% of preschool-aged children and between 50% and 90% of school-aged children and adolescents do not get as much sleep as they may need. Screen-based media devices are present in the bedrooms of 75% of children and 60% of adolescents report viewing or interacting with screens in the hour before bedtime.

And computer use was more consistently associated with poor sleep outcomes than television, perhaps because television watching may be less interactive than computer-based activities.

Lack of sleep and poor sleep quality are associated with daytime tiredness, which in turn is linked to a large number of negative outcomes, including poor school performance and a host of psychological problems.