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Prolonged screen time linked to early puberty in girls

Early-onset puberty has been linked to a laundry list of health issues later in life, including breast cancer, HPV and other conditions.

(CN) — Parents worried about their children’s exposure to harmful online content may now also have to start worrying about unsafe exposure to the device itself. Research presented at the 60th Annual European Society for Pediatric Endocrinology Meeting shows the blue light emitted by most of our modern digital devices can impact the production of hormones associated with puberty onset in children.

The study concluded that blue light can ultimately cause puberty to start much earlier, for girls in particular. Early puberty in girls has been linked to higher risk of breast cancer, HPV, and other medical conditions later in life.

In the study, researchers exposed groups of rats to blue light in cycles. The female rats received either a control amount, six hours, or twelve hours of light in an attempt to replicate human screen times.

“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,” said study co-author Dr. Aylin Kilinç Uğurlu of Turkey’s Ankara City Hospital in a statement accompanying the study.

Analysis of the rats showed lowered melatonin levels and raised levels of both luteinizing hormone, which is associated with the menstrual cycle, and estradiol, a hormone responsible for development of secondary sexual characteristics. All of this added up to an overall earlier puberty onset in the rats.

“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.

As anyone who has found themselves wide awake after scrolling their phone before bed can attest to, blue light can disrupt sleep patterns and cause eye strain and headaches. Blue light, emitted by smartphones, laptops, and pretty much anything with a screen nowadays, has been a cause of concern for medical professionals since digital devices have become inescapable parts of our lives. 

According to previous studies, exposure to blue light largely affects melatonin — the hormone that regulates the sleep cycle — levels in both children and adults. Lowered melatonin disrupts the circadian rhythm and the light itself has been studied for risk of damage to the eye. The interruption to normal sleep patterns can affect childhood development and mental health.

These harmful effects, compounded with these new signs of the threat to childhood development, create a compelling argument for putting down the phone at night.

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

The effect on hormones significant to puberty may affect not only early development but also future fertility. The study found the rats that were subjected to especially prolonged exposure developed concerning physical changes in their ovarian tissue, which manifested in both cell death and polycystic growth. In humans, this can impact reproductive health and fertility.

Past studies during the rise of digital technology in the daily lives of younger and younger children have pointed toward an increase in earlier onset puberty in girls. There is a particular surge associated with the Covid-19 pandemic, as children have had no choice but to increase exposure to screens and blue light for online studies.

The 60th Annual European Society for Pediatric Endocrinology Meeting, the first since the beginning of the pandemic, has been held in Rome this week. Uğurlu’s study was presented on Thursday.

Categories / Health, Science

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