Children's screentime could be linked to cell damage and early onset of puberty

The study by Aylin Kilinc Ugurlu links exposure to blue light (which is emitted by phones and similar devices) with cell damage in rats, and suggests a similar link in humans. Stock picture

Regular use of smartphones, tablets, and other devices emitting blue light may alter children's hormone levels and increase the risk of earlier puberty, according to a new study.

Blue light is known to reduce sleep quality in children and adults, as it inhibits the evening rise in levels of melatonin which prepares the body for sleep.

The research suggests blue light exposure and reduced melatonin levels linked to increased screen time, such as during the pandemic restrictions, may be playing a role in the reported increase of early puberty onset, according to the study.

The findings are being presented at the 60th annual meeting of the European Society for Paediatric Endocrinology in Rome. 

The study, carried out by Aylin Kilinc Ugurlu and her colleagues in Ankara, Turkey, used rats to investigate the effects of blue light exposure on reproductive hormone levels.

Female rats were divided into three groups of six which were variously exposed to a normal light cycle; six hours of blue light; or 12 hours of blue light.

The first signs of puberty occurred significantly earlier in the groups exposed to blue light and the longer the duration of exposure, the earlier the onset of puberty.

The rats exposed to blue light also had reduced melatonin levels and elevated levels of reproductive hormones as well as physical changes in their ovarian tissue, all of which are consistent with puberty onset.

The rats exposed to the longest duration of blue light, 12 hours, also showed some signs of cell damage and inflammation of their ovaries.

Alex Cooney. the CEO of CyberSafeIreland, said '[W]e’d urge that there isn’t device use close to bedtime and that devices are kept out of bedrooms, especially for younger children.' File picture

The research team plans to investigate the cell damage and inflammatory effects detected after the longer duration of blue light exposure as they could have long-term impacts on reproductive health and fertility, according to Dr Kilinc Ugurlu. 

They will also assess whether device features which minimise blue light can reduce the effects observed in the study.

Reacting to the findings, Alex Cooney, CEO of Cyber Safe Kids, said: "We need a healthy offline/online balance to be there. We need to take a break from devices.” 

She added that parents ought to set ground rules concerning the use of and access to devices.

“Certainly, in relation to children we’d urge that there isn’t device use close to bedtime and that devices are kept out of bedrooms, especially for younger children because too often, that’s not the case,” she said.