Blue light exposure via regular use of tablets and smartphones may alter hormone levels and increase the risk of precocious puberty, according to data from a rat study presented today in 60th Annual Meeting of the European Society of Pediatric Endocrinology. Longer exposure to blue light was associated with early onset of puberty in female mice, which also showed decreased levels of melatonin, increased levels of certain reproductive hormones, and physical changes in the ovaries. The use of blue light-emitting mobile devices has previously been linked to disturbed sleep patterns in children. However, these findings suggest that there may be additional risks to childhood development and fertility in the future.
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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 happen by disrupting our bodily clock because blue light prevents the rise in levels of the evening 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 an epidemic, may play a role in this reported increase. However, it is not easy 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. Mice exposed to blue light also had reduced levels of melatonin, elevated levels of certain reproductive hormones (estradiol and luteinizing hormone), and physical changes in ovarian tissue, all consistent with the onset of puberty. At 12 hours of exposure, 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.” .”
Although Dr. Aylin Kilink 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 exposure to blue light equivalent to using a baby tablet in mice. However, the time point of puberty for mice is approximately equal to that of humans if adjusted for the reduced life expectancy of mice. In addition, the hormonal changes and ovulation changes that occur during the prepubertal and pubertal period in female rats are 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 because this could have long-term effects on reproductive health and fertility. They will also evaluate whether using blue light to reduce the ‘night-light’ mobile device features can reduce the effects observed in the rat model.
“Although this is not conclusive, we recommend reducing the use of blue light-emitting devices in prepubertal children, especially in the evening when exposure has a significant effect on hormonal alteration,” adds Dr. Aileen Kilink Ugurlu.
Effects of exposure and exposure to blue light on puberty in mice
an introduction: In the past 10 years, blue light (BL) sources such as tablets and phones have increased in every age group. Because of the Covid-19 pandemic in particular, screen exposure has also increased in childhood. However, the effects of BL exposure in adulthood are not clear. Therefore, we aimed to examine the effect of BL exposure and time of exposure on puberty.
Methods: 21-day-old Sprague Dawley rats were divided into three groups of six rats in each group: control group (CG), experiment group 1 (EG-1), and experiment group 2 (EG-2). CG mice were maintained under standard conditions with 12/12 h light-dark cycles. EG-1 and EG-2 rats were exposed to BL (450-470 nm/irradiance level 0.03 uW/cm2) for 6 h and 12 h, respectively. Mice were exposed to BL until the first signs of puberty appeared and were euthanized. Serum FSH, LH, estradiol, testosterone, DHEA-S, leptin and melatonin were studied by ELISA method. The ovaries and uterus were dissected for histological examination.
consequences: The median days of entering puberty for CG, EG-1, and EG-2 were 38The tenth32second abbreviationand 30The tenth days in a row. (p: 0.001) A negative association was found between the groups’ day of entry into puberty, exposure to BL, and duration of exposure. (p: -0.910, p < 0.001)
The levels of FSH, testosterone, DHEA-S, and leptin for all groups were similar. (p > 0.05) However, the LH and estradiol levels of EG-1 were higher compared to CG. (p: 0.027) There was a negative association between BL exposure and exposure time and melatonin levels (ro: -0.537, p: 0.048). Ovarian tissue was consistent with pubertal period in all groups. With increasing BL exposure time, capillary dilatation and edema increased in suprapubic tissues. Prolonged exposure caused polycystic (PCO-like) morphological changes and apoptosis in granulosa cells.
conclusion: Our study is the first to show the effects of BL exposure on puberty. Our study showed that exposure to BL and duration of exposure lead to early puberty. In addition, PCO-like inflammation and apoptosis were detected in ovaries with increasing time of BL exposure.
Studies show an increase in precocious puberty and an acceleration of puberty during the lockdown period compared to the pre-pandemic period. Our study demonstrated the effects of BL exposure on puberty and the relationship between increased exposure time.