Teens who spend more than six hours a day staring at TV or computer could be more likely to enter puberty earlier than those who encounter less screen time, a study has suggested.
Experts at the Gazi University in Turkey exposed rats to either six hours of blue light (which is emitted from screens) or 12 hours, and found six was enough to accelerate growth.
This triggered puberty earlier than another group exposed to the same amount of natural light.
Presenting their findings at a conference in Liverpool, the team admitted their findings were limited to animals – however they said the research could be used to inform ‘preventative measures for safe screen use’ in children.
It comes as experts identify an intriguing trend of increasing numbers of girls beginning their menstrual cycles earlier than historical averages.
Research shows there was a staggering 52 per cent increase in children’s screen time between 2020 and 2022, likely due to covid lockdowns.
However, independent British experts have urged people to cautious about the study with some even labeling its conclusions ‘irresponsible’.
They say the type of light used in the study is not comparable to the blue light emitted from TVs, computers and tablets – and rats’ bodies behave differently to that of humans.
While the team, who presented their findings at a conference Liverpool, said the study obviously had limitations given it was on animals but insisted their findings had had potential implications for people. Stock image
In the study, the team took 36 baby rats and split them into three groups.
One cohort was exposed to natural light whilst the other two were exposed to six or 12 hours of blue light per day.
Experts then monitored the rats, which were split evenly in terms of sex, for the first signs of bone growth and puberty.
They found the blue light group grew faster and therefore entered puberty earlier.
But Professor Pete Etchells, an expert in psychology at Bath Spa University, who has been studying the impact of screen time, slammed the new research, which has not been published or peer reviewed.
‘This study has nothing to do with screen time, or children – it is a small study of limited blue light exposure to young rats,’ he said.
‘It is simply incorrect, then, to state that “excessive screen time” has been linked to early physical development.
Sunlight has a balance of what scientists call red and blue light and experts are concerned overexposure to the latter could cause host of potential negative health problems in the future. Stock image
‘Further, the type and intensity of light exposure used here is not easily translatable to the practical reality of how children interact with screen-based technologies.
‘I’m therefore not clear what, if anything, this study adds in terms of informing and reassuring the very real concerns that many people have about the potential positive and negative impacts of screen-based technologies.
Another critic was Professor Dorothy Bishop, an expert in developmental neuropsychology at the University of Oxford.
‘I would urge strong caution in drawing any conclusions from this study about impact of light from screens on children,’ she said.
She highlighted that rat development is vastly different from humans, and the methods used in the study did not reflect childrens’ lives.
For instance, the rats weren’t given any breaks from looking at the light, which doesn’t mimic how children use technology.
However, experts in general have raised concerns about the potential impact of chronic exposure to blue light.
Earlier this year scientists at University College London (UCL) warned it could represent a public health ‘time bomb’ – potentially causing diabetes and even shortening lives.
Sunlight has a balance of what scientists call red and blue light.
As blue light is naturally seen during daylight when the sun is shining, it naturally boosts our attention, reaction times, and mood, essentially making us more awake.
But modern LED lighting as well as rising screen use has led to a much higher exposure of blue light than in previous generations.
Experts who have found excessive blue light can disrupt how our cells work, as well as scramble our circadian rhythm, the body’s internal clock, leading to a host of negative health consequences.