News | Can Prolonged Smartphone Use Cause Precocious Puberty in Children? Study Examines the Effects of Blue Light
Smartphones and tablets are now part of children's daily lives. However, a recent study suggests that excessive blue-light exposure may alter hormone levels and increase the risk of earlier puberty.
At the 60th Annual Meeting of the European Society for Paediatric Endocrinology, researchers presented a rat-model study showing that longer blue-light exposure was associated with earlier puberty. The rats also had lower melatonin levels, higher levels of certain reproductive hormones, including estradiol and luteinizing hormone, and corresponding physiological changes in ovarian tissue.
How Might Blue Light Affect Pubertal Development?
Previous research has found that blue light may affect sleep quality by suppressing nighttime melatonin secretion. Melatonin regulates the body's circadian rhythm. Its levels are higher before puberty and gradually decline after puberty begins, so changes in melatonin may be associated with the onset of puberty.
Children's screen time increased substantially during the pandemic, while recent research has also identified an increase in earlier puberty among girls. Some researchers have proposed increased screen time as a potential contributor, but direct experimental studies in children are difficult because of individual variation.
How Was the Study Conducted?
Dr. Aylin Kilinç Uğurlu and her team in Ankara, Türkiye, used a rat model to study the effect of blue-light exposure on the onset of puberty. They divided 18 female rats aged 21 days into three groups of 6:
Control group (CG): A normal 12-hour light-dark cycle
Experimental group 1 (EG-1): 6 hours of blue-light exposure per day
Experimental group 2 (EG-2): 12 hours of blue-light exposure per day
The results showed:
Rats exposed to blue light entered puberty earlier.
The average onset of puberty was day 38 in the control group
Day 32 in the 6-hour blue-light group
Day 30 in the 12-hour blue-light group
Longer blue-light exposure was associated with lower melatonin and higher estradiol and luteinizing hormone levels, key hormones in the onset of puberty.
Changes in ovarian tissue: Rats with prolonged blue-light exposure showed dilated capillaries, edema, and inflammation in ovarian tissue, with some features resembling polycystic ovary syndrome (PCOS).
Could Children Be Affected in the Same Way?
Although the study was conducted in rats, the timing of puberty in rats has similarities to humans. Researchers noted that hormonal changes around puberty in rats resemble those in girls, so the findings may have some relevance to humans.
Dr. Aylin Kilinç Uğurlu said:
“Our study shows that blue-light exposure can alter melatonin levels and affect reproductive hormone secretion, leading to earlier puberty. Although we cannot yet determine whether these findings apply to children, the data suggest that blue light may be a potential risk factor for early puberty.”
The study also found that prolonged blue-light exposure may cause ovarian tissue damage and inflammation, which could affect future fertility.
Future Research and Health Recommendations
The team plans to study the cellular damage and inflammatory effects caused by blue-light exposure and assess whether reducing nighttime exposure, such as by using a night mode, can lessen these effects.
Although there is currently no conclusive evidence that blue light directly causes precocious puberty in children, experts recommend:
Reducing blue-light exposure in children, particularly before puberty and especially at night
Keeping children away from electronic screens for 1 hour before bedtime to avoid disrupting melatonin secretion
Increasing exposure to natural light; outdoor activity may support normal circadian rhythms and hormone levels
Using an eye-comfort mode or reducing screen brightness to limit blue-light effects on the endocrine system
Dr. Aylin Kilinç Uğurlu concluded:
“Although this study cannot establish a direct conclusion, we still recommend that parents limit blue-light device use by prepubertal children, especially at night, to reduce possible hormonal disruption.”
Conclusion
This study provides experimental evidence of an association between blue-light exposure and earlier puberty. More research is needed to confirm the effects in humans, and future studies will examine the long-term impact of blue light on hormonal regulation and reproductive health to inform screen-time recommendations.
News | Can Prolonged Smartphone Use Cause Precocious Puberty in Children? Study Examines the Effects of Blue Light
News | Can Prolonged Smartphone Use Cause Precocious Puberty in Children? Study Examines the Effects of Blue Light
Smartphones and tablets are now part of children's daily lives. However, a recent study suggests that excessive blue-light exposure may alter hormone levels and increase the risk of earlier puberty.
At the 60th Annual Meeting of the European Society for Paediatric Endocrinology, researchers presented a rat-model study showing that longer blue-light exposure was associated with earlier puberty. The rats also had lower melatonin levels, higher levels of certain reproductive hormones, including estradiol and luteinizing hormone, and corresponding physiological changes in ovarian tissue.
How Might Blue Light Affect Pubertal Development?
Previous research has found that blue light may affect sleep quality by suppressing nighttime melatonin secretion. Melatonin regulates the body's circadian rhythm. Its levels are higher before puberty and gradually decline after puberty begins, so changes in melatonin may be associated with the onset of puberty.
Children's screen time increased substantially during the pandemic, while recent research has also identified an increase in earlier puberty among girls. Some researchers have proposed increased screen time as a potential contributor, but direct experimental studies in children are difficult because of individual variation.
How Was the Study Conducted?
Dr. Aylin Kilinç Uğurlu and her team in Ankara, Türkiye, used a rat model to study the effect of blue-light exposure on the onset of puberty. They divided 18 female rats aged 21 days into three groups of 6:
Control group (CG): A normal 12-hour light-dark cycle
Experimental group 1 (EG-1): 6 hours of blue-light exposure per day
Experimental group 2 (EG-2): 12 hours of blue-light exposure per day
The results showed:
Rats exposed to blue light entered puberty earlier.
The average onset of puberty was day 38 in the control group
Day 32 in the 6-hour blue-light group
Day 30 in the 12-hour blue-light group
Longer blue-light exposure was associated with lower melatonin and higher estradiol and luteinizing hormone levels, key hormones in the onset of puberty.
Changes in ovarian tissue: Rats with prolonged blue-light exposure showed dilated capillaries, edema, and inflammation in ovarian tissue, with some features resembling polycystic ovary syndrome (PCOS).
Could Children Be Affected in the Same Way?
Although the study was conducted in rats, the timing of puberty in rats has similarities to humans. Researchers noted that hormonal changes around puberty in rats resemble those in girls, so the findings may have some relevance to humans.
Dr. Aylin Kilinç Uğurlu said:
“Our study shows that blue-light exposure can alter melatonin levels and affect reproductive hormone secretion, leading to earlier puberty. Although we cannot yet determine whether these findings apply to children, the data suggest that blue light may be a potential risk factor for early puberty.”
The study also found that prolonged blue-light exposure may cause ovarian tissue damage and inflammation, which could affect future fertility.
Future Research and Health Recommendations
The team plans to study the cellular damage and inflammatory effects caused by blue-light exposure and assess whether reducing nighttime exposure, such as by using a night mode, can lessen these effects.
Although there is currently no conclusive evidence that blue light directly causes precocious puberty in children, experts recommend:
Reducing blue-light exposure in children, particularly before puberty and especially at night
Keeping children away from electronic screens for 1 hour before bedtime to avoid disrupting melatonin secretion
Increasing exposure to natural light; outdoor activity may support normal circadian rhythms and hormone levels
Using an eye-comfort mode or reducing screen brightness to limit blue-light effects on the endocrine system
Dr. Aylin Kilinç Uğurlu concluded:
“Although this study cannot establish a direct conclusion, we still recommend that parents limit blue-light device use by prepubertal children, especially at night, to reduce possible hormonal disruption.”
Conclusion
This study provides experimental evidence of an association between blue-light exposure and earlier puberty. More research is needed to confirm the effects in humans, and future studies will examine the long-term impact of blue light on hormonal regulation and reproductive health to inform screen-time recommendations.
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