Exposure to blue light, via regular use of tablets and smartphones, may alter hormone levels and increase the risk of precocious puberty, according to data from a study in mice presented today at the 60th annual meeting of the European Society of Pediatric Endocrinology.
longest duration blue light Exposure was linked earlier puberty Beginning in female rats, which also showed decreased levels of melatonin, and increased levels of some reproductive hormones and physical changes in the ovaries. The use of blue light-emitting portable devices has previously been linked to disturbed sleep patterns in children, but these findings suggest that there may be additional risks to children’s development and fertility in the future.
The escalating use of blue light-emitting devices, such as tablets and smartphones, has been previously implicated in reducing sleep quality in both children and adults. This is thought to occur by perturbing our bodily clock as blue light prevents the evening rise in levels of the hormone melatonin, which prepares our bodies for rest and sleep. Melatonin levels are generally higher during the prepubertal period than during puberty, which is thought to play a role in delaying the onset of puberty. Puberty is a complex process that involves the coordination of many body systems and hormones.
In recent years, several studies have reported increases in the onset of early puberty for girls, particularly during the COVID-19 pandemic. The association between exposure to blue light and decreased levels of melatonin suggests that increased screen time, such as during pandemic restrictions, may play a role in this reported increase. However, it is very difficult to assess this in children.
In this study, Dr. Aylin Kilinç Uğurlu and colleagues in Ankara, Turkey, used a rat model to investigate the effects of blue light exposure on reproductive hormone levels and the time of onset of puberty. Female mice were divided into three groups of six and exposed to either a normal, 6-h or 12-h blue light cycle. The first signs of puberty occurred significantly earlier in both groups exposed to blue light, and the longer the exposure, the earlier the onset of puberty. The mice exposed to the blue light also had reduced levels of melatonin and elevated levels of certain reproductive hormones (estradiol and luteinizing hormone), as well as physical changes in ovarian tissue, all consistent with the onset of puberty. On exposure for 12 hours, the mice also showed some signs of cell damage and inflammation in their ovaries.
Dr. Aylin Kilink Ugurlu comments, “We have found that exposure to blue light, which is sufficient to alter melatonin levels, is also able to alter reproductive hormone levels and cause the onset of early puberty in our rat model. Additionally, the higher the exposure, the earlier it is.” .”
However, Dr. Ugurlu cautions, “Because this is a study in mice, we cannot be certain that these findings will be replicated in children, but these data suggest that exposure to blue light may be considered a risk factor for early onset of puberty.”
It is difficult to mimic blue light exposure equivalent to using a pediatric tablet in mice, but the time point of puberty for mice is roughly equivalent to that of humans, if adjusted for the mice’s lower life expectancy. The hormonal changes and ovulation that occur during the prepubertal and pubertal period in female rats are also comparable to humans. Therefore, despite study limitations, these findings support further investigation of the potential health effects of blue light exposure on hormone levels and the onset of puberty in children.
The team plans to investigate the cell damage and inflammatory effects detected after prolonged exposure to blue light, as this may have long-term effects on reproductive health and fertility. They will also evaluate whether the use of blue light that reduces the mobile device’s “night light” features can reduce the effects observed in the rat model.
“Although this is not conclusive, we recommend reducing the use of blue-light devices in prepubertal children, especially in the evening when exposure has a significant effect on hormonal alteration,” adds Dr. Ugurlu.
Summary P1-361: Blue light exposure and effects of exposure duration on puberty in mice, www.eurospe.org/meetings/2022/espe-2022/programme/
Presented by the European Society of Pediatric Endocrinology
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