Yet protection from the harmful effects to the retina offered by “anti-blue light” screens, filters and sunglasses varies, and their ability to preserve sleep rhythms is not proven, ANSES also said.
LEDs or light-emitting diodes consist of a semiconductor chip positioned on a reflective surface; when electricity runs through the semiconductor, light is produced.
ANSES differentiates types of blue light in its report. For example, “warm white” domestic LED lighting has weak phototoxicity risks, similar to traditional lighting, according to ANSES. However, other LED lighting sources, including the newest flashlights, car headlights and some toys, produce a whiter and “colder” blue light that is more harmful.
Additional scientific evidence
“There are blue light photoreceptors in the retina that directly communicate with the brain circadian clock,” Tosini, who was not involved in the ANSES report, wrote in an email. “It is true that exposure to light in the evening affect sleep and circadian rhythms mostly by inhibiting the synthesis of the sleep promoting hormone melatonin.”
Yet he also said that a few studies have shown that “exposure to blue light in the middle of the day may have beneficial effects” in that it increases alertness.
The retina “accumulates fluorescent molecules generally referred to as lipofuscin,” explained Sparrow, who was not involved in the ANSES report. “These compounds become more abundant with age and are sensitive to blue light.” Early evidence suggests that this light sensitivity may lead to unhealthy optical responses over the long term, she said.
Tosini noted that scientists are convinced that exposure to LED blue light in the range of 470 to 480 nanometers for a short to medium period (days to weeks) should not significantly increase the risk of eye disease, but the same is not necessarily true for long-term exposure (months to years).
“I believe that more studies are needed on this topic that is really affecting the health of many citizens,” he said. He added a potential solution to the problem of blue light would be to develop intelligent lighting systems that change the composition of lighting throughout the day.
However, Sparrow said that, generally, sunglasses block ultraviolet light, and those “that have a yellow tint should be preferred as they will also reduce the amount of blue light that reaches the retina.”
Ultimately, ANSES believes the recommended maximum limit on short-term exposure to blue light should be revised downward, even if most people would only rarely be able to meet that level. Children and teenagers, whose eyes do not fully filter blue light, are particularly sensitive to the harms of cold blue light, the French authority noted. The agency also recommended that only low-risk LED devices be available to consumers and the luminosity of car headlights be reduced.
CNN’s Barbara Wojazer contributed to this report.