Blue light has been under the lens of science for years: it seems to cause damage to the eyes, generate oxidative stress on the skin and cause sleep disturbances, especially in younger people.
Research conducted on mice and presented at the 60th Annual Meeting of the European Society of Pediatric Endocrinology, held in September in Rome, showed that exposure to blue light from tablets and smartphones can alter hormone levels and increase the risk of precocious puberty.
The blue light
The light visible to the human eye is between 380 and 780 nanometers, the blue component is between 380 and 500 nanometers and can be harmful with shorter wavelength radiation. Unlike UV rays, which are absorbed by the cornea and the lens, blue light penetrates the lens, reaches the retina and interacts with the macular pigment epithelium and photoreceptors, causing cell damage.
According to some studies, this kind of lighting alters our body clock by inhibiting the evening increase in the levels of the hormone melatonin, which prepares our body for rest and sleep. The same inhibition may be involved in growth processes: melatonin levels are overall higher during pre-puberty than in puberty, and this is thought to play a role in delaying the onset of the complex transition involving coordination of several body systems and hormones.
In recent years, mainly due to the pandemic, exposure to blue light via cell phones and computers has increased. In parallel, several studies have shown an increase in the onset of puberty in girls and this is certainly not a coincidence.
The team from the Pediatric Endocrinology Clinic, Ankara, Turkey studied the effects of blue light on reproductive hormone levels and the time of onset of puberty on mice. The 21-day-old females were divided into three groups, each consisting of six elements. The first was exposed to a normal light cycle, the others to six and twelve hours of blue light, respectively. In these last two groups, the first signs of puberty occurred much earlier than in the control group: the longer exposure corresponded to a more rapid development of the signals. In fact, elevated levels of reproductive hormones and a lowering of melatonin levels have been verified, as well as changes in ovarian tissue. At the same time, after 12 hours of exposure, the mice showed signs of cell damage and ovarian inflammation.
The new study indicates that, with prolonged exposure, there may be additional risks to infant development and future fertility. Obviously, the big limitation is that the research has been carried out on mice, so it is very difficult to imitate in the laboratory an exposure similar to that one would have on children, even if the hormonal changes are comparable. The study, without prejudice to the need for further investigations, however calls for minimizing the use of devices that emit blue light especially by children of pre-pubertal age and especially in the evening, when exposure inhibits increased melatonin and has hormonal effects.