If you’re wondering if blue light exposure can cause precocious puberty, you might not want to check your smartphone too often for the answer. More and more studies have shed light on the potential risks associated with the use of such mobile devices emitting blue light. And a study presented September 16 at 60th Annual European Society of Pediatric Endocrinology Meeting found that blue light exposure was associated with decreased levels of melatonin, increased levels of two major reproductive hormones (estradiol and luteinizing hormone), and changes in ovarian tissue that may indicate early onset puberty in women. In fact, changes occurred even after only six hours of blue light exposure, which really isn’t that long. That’s how long it would take to watch the “Baby Shark Dance” video on YouTube only about 159 times, depending on how many ads have to click along the way.
Now, if you had said “rats” to this study, you would have been right. The subjects of this study were not humans but rather rats, female rats. As described in the study abstract, the team from Gazi University Faculty of Medicine in Ankara, Turkey, (Aylin Kılınç Uğurlu, Aysun Bideci, Ayşe Mürşide Demirel, Gülnur Take Kaplanoğlu, Duygu Dayanır, Özlem Gülbahar, Tuba Saadet Deveci Bulut, Esra Döğer, and M. Orhun Çamurdan) divided 18 immature female Sprague Dawley rats into three groups of six rats each. In this case, “immature” did not mean that they said “nonsense” too often. This meant that they were 21 days old and had not yet reached puberty. Six of the rats were in the control group under standard 12 hour light and 12 hour cycles typical of “natural” conditions. Six other rats underwent six hours of exposure to blue light (450-470 nm/irradiance level 0.03 uW/cm2). The third group of six rats had an even longer exposure (12 hours) to blue light.
While the female rat in the control group entered puberty on average day 38, those in the six-hour blue light exposure group entered puberty much earlier, on average day 32. Those in the 12-hour blue light exposure group began puberty even earlier, on day 30 on average. Longer durations of blue light exposure were associated with earlier puberty in rats. The researchers also found significantly higher levels of luteinizing hormone and estradiol in rats given at least six hours of blue light exposure compared to the control group. Additionally, longer exposure to blue light was correlated with lower melatonin levels. Finding signs of inflammation, such as dilated blood vessels and fluid accumulation, in the ovaries provided further evidence that the rats had indeed entered puberty. In fact, the research team found polycystic ovary-like (PCO-like) changes in female rats that had been exposed to blue light.
Of course, humans aren’t rats, at least not in the physical sense, no matter what you think of your school and work colleagues. Rats differ from humans in various ways, such as body size, number of days to onset of puberty, life expectancy, and propensity to bear mules. It would be rather alarming for a human infant to begin puberty after only 38 days. So not all rat studies will necessarily apply to you or your children, assuming you don’t have whiskers and tails. Plus, it’s not like the study is giving rats small smartphones and Instagram (or maybe Instacheese) accounts. Although the researchers tried to mimic blue light exposure from smartphones to some extent, the study was unable to replicate the exact conditions associated with human smartphone use.
Moreover, the threshold for presenting a study at a scientific meeting is much, much, much lower than the threshold for publishing it in a respectable peer-reviewed scientific journal. What is presented at scientific meetings can be a mixture of very good studies, good studies, OK studies, not-so-good studies, and this-is-never-going-to-make-a-true- respectable-scientific -journal studies.
That being said, this latest study offers some good insight into what could be a growing problem. Before I say rats going through puberty aren’t the same because they don’t listen to Taylor Swift or Nirvana, keep in mind that rats generally progress through pre-pubertal and pubescent hormonal and ovulatory changes. similar to those of humans. And taking differences in life expectancy into account, rats actually begin puberty at similar life stages to humans.
Plus, consider this yet another piece of evidence that too much blue light exposure could mess with your bodies and your children’s bodies in various ways. This is certainly not the first study to raise concerns about how exposure to blue light may affect human hormone levels. For example, previous studies have found associations between blue light exposure and changes in melatonin and cortisol levels. This video from Hamilton Health Sciences in Hamilton, Ontario, Canada, showed how blue light can affect the release of melatonin from your pineal gland:
Studies have shown that the use of blue light-emitting mobile devices is correlated with disruptions in sleep patterns potentially due at least in part to changes in melatonin levels. And your melatonin levels tend to be highest just before you hit puberty. Melatonin, in some ways, behaves like Wilson Phillips and says “hang on” to your body to prevent the early onset of puberty.
Then there’s all that “prior” evidence out there. Over the past decade, as covered by Jessa Gamble for Nature, the researchers noted how girls on average are entering puberty at an increasingly earlier age. There have been reports of girls developing breasts as young as six years old. The problem is that it may be the result of the increasing amount of artificial beeps around us, such as more and more chemicals in the environment, more and more things being added to food, and more and more blue light.
Remember, it’s unclear how many tech companies said, “well, I wonder how this is all going to affect everyone’s health” before rolling out all the smartphones, apps, and social media that now invade our society. Just because everyone seems to be using something doesn’t necessarily mean it’s 100% safe. So you really don’t know what the constant use of smartphones and similar devices can do to you. Further studies are needed to shed light on the subject and how to protect yourself. In the meantime, you may want to do your best to limit your exposure and that of your children to blue light.
Remember the immortal words of Eiffel 65, who first said in 1998, over two decades ago, “Yo, listen. This is the story of a little guy who lives in a blue world. And all day and all night. And all he sees is blue like him inside and out. Maybe that song wasn’t about blue light exposure back then. But these days, things might be looking a little too blue in more ways than one.