A new study provides more evidence that parents should limit children’s screen time. Turkish researchers discovered a connection between blue light exposure from smartphones, tablets and similar devices and the onset of early puberty.

According to Study Finds, these findings highlight the impact modern habits, such as increased screen time, can have on the physiological development of children. In recent years, puberty has been starting earlier in both girls and boys. While early puberty can be caused by genetics, brain abnormalities, such as tumors, or issues with the thyroid, adrenal or sex glands, scientists have now found that more blue light exposure may lead to earlier puberty.  

Researchers from the Ankara Bilkent City Hospital and Gazi University in Turkey observed 18 male rats, all 21 days old. They split the rodents into three groups that received varying degrees of blue light daily: a normal light cycle, six hours, or 12 hours. The male rats exposed to more blue light started puberty notably sooner. These rats also had hindered sperm development and showed signs of testicular tissue damage, says Study Finds.

The same group of researchers also found that female rats exposed to blue light displayed early signs of puberty in previous research.

“For the first time, we found a direct relationship between blue light exposure and early puberty in male rats,” said Aylin Kilinҫ Uğurlu from Ankara Bilkent City Hospital in a news release. “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.”

Uğurlu stressed that more research is needed.

“I want to emphasize 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.”

Blue light is already well-known to disrupt circadian rhythms by suppressing the production of the sleep hormone melatonin, says the New York Post, delaying the onset of sleep. For teenagers, especially, lack of sleep can lead to academic and emotional struggles. The new research adds even more weight to the need for young people to learn how to reduce screen time on digital devices.