Excessive Smartphone Use Could Bring On Early Puberty In Children

Excessive use of tablets and smartphones could help bring on early puberty in children, according to a new study.

Studies on rats showed that exposure to the blue light emitted from some electronic devices was associated with altered hormone levels, triggering physical changes associated with puberty.

Although there is no guarantee the findings would be replicated in children, researchers say the data suggests that excessive exposure to blue light should be considered a risk factor for the onset of early puberty.

Studies from across Europe and the United States have found that girls are now entering puberty almost a year earlier than they did four decades ago.

While the data is more ambiguous for boys, some studies have found a similar pattern, of children entering puberty earlier than in previous generations.

Rising levels of obesity have been identified as one possible cause for early puberty in both sexes, but now researchers suggest smartphones may have a role to play as well.

For the latest study, researchers in Ankara, Turkey, found that female rats exposed to blue light showed the first signs of puberty significantly earlier than rats exposed to a normal light cycle.

The longer the duration of exposure, the earlier the onset of puberty, according to the study, presented today at a meeting of the European Society for Paediatric Endocrinology.

As well as physical changes in their ovaries, the rats exposed to blue light also showed higher levels of reproductive hormones. The rats exposed to the most blue light also showed signs of cell damage and inflammation in their ovaries.

Exposure to blue light was also associated with lower levels of melatonin, a hormone linked to the sleep cycle. Melatonin levels fall during puberty and are believed to play a role in delaying puberty.

A rise in levels of melatonin in the evenings is thought to be preparing the body for sleep. Previous studies have suggested blue light disrupts this process and reduces the quality of sleep in both children and adults.

“Blue light exposure, sufficient to alter melatonin levels, is also able to alter reproductive hormone levels and cause earlier puberty onset in our rat model,” said Dr Aylin Kilinç Uğurlu, of Ankara City Hospital and lead author of the study.

“In addition, the longer the exposure, the earlier the onset,” he added.

Although the researchers acknowledge the limitations of a study on rats, puberty in rats occurs at a roughly equivalent stage to humans, adjusting for rats’ shorter lifespan.

And changes in hormone levels and ovulation in rats during puberty are also roughly comparable to those that take place in humans.

The findings support the need for further research into the health impacts of exposure to blue light, in particular into the impact on hormone levels and the onset of puberty.

“As this a rat study, we can’t be sure that these findings would be replicated in children but these data suggest that blue light exposure could be considered as a risk factor for earlier puberty onset,” Dr Uğurlu said.

“Although not conclusive, we would advise that the use of blue light emitting devices should be minimised in pre-pubertal children, especially in the evening when exposure may have the most hormone-altering effects.”

The team plans a follow-up study to investigate the cell damage and inflammation detected after longer blue light exposure, since this could have long-term impacts on reproductive health and fertility.

They will also examine the potential of blue light minimising ‘night light’ mobile device features to reduce the effects of exposure to blue light.