Blue light from smartphones, tablets linked to early puberty in males

Exposure to blue light, like that from smartphones or tablets, may lead to early puberty in males, according to a study in mice.

The research, presented at the ongoing 61st Annual European Society for Paediatric Endocrinology Meeting in The Hague, Netherlands, sheds light on how environmental factors, such as screen time, impact early puberty and testicular tissue, which could eventually lead to future prevention strategies for children.

Early puberty for most children does not have an obvious cause. Sometimes it is due to genetics, or there is a problem in the brain, such as an injury or tumour, or in the thyroid, adrenal or sex glands.

In recent years, several studies have reported increases in early puberty onset for both girls and boys, particularly during the Covid-19 pandemic. One factor may be the increased use of blue light-emitting devices, but this is very difficult to assess in children.

In this study, researchers from the Ankara Bilkent City Hospital and Gazi University in Turkey examined 18 male rats aged 21-days-old, divided into three groups of six and exposed to either a normal light cycle, to six hours or 12 hours of blue light.

The researchers found that the first signs of puberty occurred significantly earlier in male rats exposed to blue light. Additionally, the longer the rats were exposed to blue light, the earlier their puberty started, while they also showed suppressed sperm development and damaged testicular tissue.

“For the first time, we found a direct relationship between blue light exposure and early puberty in male rats,” said lead researcher Dr Aylin Kilinc Ugurlu from Ankara Bikent City Hospital.

“Our findings align with our previous work on female rats, which also showed similar effects, thereby providing a more comprehensive view of how blue light may influence puberty in both male and female rats,” Ugurlu added.

While the findings suggest that blue light exposure could potentially be a risk factor for earlier puberty onset, more research is needed, the researchers said in the paper published in Frontiers in Endocrinology.

“I want to emphasise that this is a rat study and direct results cannot be interpreted for humans. However, we provide an experimental foundation to further investigate the health consequences of ever-increasing screen time in modern society,” Ugurlu said.

The researchers will next focus on assessing the impact of blue light exposure before puberty in adult rats.