Exposure to blue light can up the risk of early onset puberty and even disrupt fertility

Exposure to the blue light emitted by cell phones and tablets in young age can increase a child’s risk of early onset puberty and can even damage their fertility in the future, a new study finds.

A Turkish research team found that blue light increased the levels of reproductive hormones in rats that were regularly exposed to it, causing them to go through puberty earlier and suffer changes to their ovaries that could potentially damage future fertility.

The dangers of blue light to sleep have long been explored and reported on, but experts fear that the rampant use of smartphones and tablets among the youth could be more harmful than anyone could have previously imagined.

It could also explain the jump in precocious puberty – when a child goes through puberty well before typical timing – suffered during the COVID-19 pandemic as millions of children spent hours more each day staring at screens.

Early puberty has been linked to higher rates of depression and anxiety throughout life, and even breast and uterine cancer.

‘We have found that 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. In addition, the longer the exposure, the earlier the onset,’ Dr Aylin Kilinç Uğurlu said in a statement.

Researchers, who will present their findings Friday at the 60th Annual European Society for Paediatric Endocrinology Meeting, gathered 18 female rats for the study.

The rodents were split into three groups. One was placed on a normal light cycle, while the other two were exposed to either six or 12 hours of blue light each day.

In both of the blue light groups, puberty occurred significantly earlier than what would be expected.

Rats in the 12 hour group had earlier puberty than the six hour group as well, showing a correlation between increased blue light exposure and time of puberty.

The rats in the two blue light groups displayed elevated levels of oestradiol and luteinising reproductive hormones as well, which is consistent with early onset puberty.

Physical changes within the rats’ ovarian tissue was noted by the research team as well.

Researchers are unsure how consistent these findings would be with humans, but still point out a potential risk these ever-present devices can carry.

‘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,’  Uğurlu said. 

The rats in the study were also found to have lower levels of melatonin than their peers – consistent with the harm that blue light has on human sleep as well.

Researchers fear that a generation of young children raised in a world where the devices are near-all-consuming will cause rates of precocious puberty to spike – carrying many negative side-effects with it.

Rates of early puberty in young girls in particular are rising, and have been for decades.

The average age of puberty in the U.S. has dropped from the typical, biologically recognized, age of 12, to 10 for females. Black and Hispanic girls in particular are going through puberty around year earlier on average. 

Experts told DailyMail.com in June that America’s growing obesity crisis could be the root cause, blaming poor diets for pushing up puberty. 

Others think it could be caused by violent childhoods, and there is also the theory that it is linked to imbalance of certain hormones. 

There are also the negative long-term downsides, like an association between early puberty and developing cancer – which remains unexplained for now – and the traumatic experiences caused by a young girl growing up just a little too quickly.

The Turkish research team notes that rates of precocious puberty are believed to have rocketed over the past two years, and fear that the increased screen time for many children during lockdowns may have played a role.