A leading professor has expressed concern about the impact of increased screen use on the sleep patterns of primary school children.

According to consultant paediatrician, Prof Alf Nicholson, both adults and children have become "highly dependent" on screens for both work and education purposes during the COVID-19 pandemic, with the result that "we now communicate via screens more than ever".

However, evidence is mounting that the use of screens by young children in the evening time is having a detrimental impact on both their sleep quantity and quality, he noted.

The American Academy of Sleep Medicine recommends nine to 11 hours of sleep for primary school children and eight to 10 hours for adolescents. This means that if a child gets up at 7am, they should be in bed by 7.30pm if aged five to seven years (allowing 30 minutes to settle), by 8.30pm if they are aged eight to 10, and by 9.30am if aged between 11 and 12.

Prof Nicholson pointed out that these are broad estimates and different children may need more or less sleep depending on their situation. However, he emphasised that insufficient sleep is linked with a number of negative physical and mental health outcomes.

For example, not getting enough sleep is associated with unhealthy dietary habits, such as skipping breakfast and increased fast food consumption.

He pointed to a large study that was carried out between 1905 and 2008, which found that over the last century, sleep duration has decreased by one hour per night.

"The advent of almost universal smartphone technology has the likely effect of shortening sleep duration even further in school-going children. Also, the blue light emitted by smartphones and tablets simulates daylight and thereby inhibits melatonin production, which is key in helping us to both fall asleep and to stay asleep," Prof Nicholson explained.

He also pointed to other studies, including a German study, which found children and adolescents who slept less had "significantly increased screen time", and less sleep was linked with unhealthy dietary habits, overweight status and poor aerobic fitness.

Prof Nicholson noted that video games and smartphones may be more disruptive to sleep than television. He said that TV involves "passive observation", whereas smartphones and other internet-enabled devices "are particularly concerning because they act as portals to a vast array of content".

Furthermore, if these devices are allowed in a child's bedroom, this can further affect sleep by, for example, emitting audible notifications when not in use.

"These alerts may not only delay sleep, but also interrupt it, thereby reducing overall quality of sleep. The proliferation of new devices has led to many children now being engaged with a screen for well over four hours per day outside of school hours," Prof Nicholson said.

Previous research has already linked the presence of a television in a child's bedroom with a number of worrying factors, such as increased weight gain, decreased academic achievement and behavioural problems.

Sleep deprivation overall leads to issues such as inattention, cognitive, and behavioural deficits, which can have implications for long-term development. Sleep deprivation has also been recognised as a modifiable risk factor in child and adolescent depression.

Prof Nicholson concludes that smartphone use late in the evening "is associated with lost sleep time and this has very significant consequences for both physical and mental health in children".

"Curtailing smartphone use is a real challenge given its popularity, but is justified based on current evidence. It is now time to reclaim this lost sleep," he added.

Prof Nicholson, formerly of Temple Street Children's University Hospital, is now vice-president for academic affairs with the Royal College of Surgeons in Ireland (RCSI) Bahrain. He made his comments in an editorial of the Irish Medical Journal.