Blue light and longevity | Scientific and technological news (Amazings® / NCYT®)

Natural light is crucial for our circadian rhythm, the 24-hour cycle of physiological processes such as brain wave activity, hormone production and cell regeneration.

But there is evidence to suggest that increased exposure to artificial light is a risk factor for sleep and circadian rhythm disorders. And with the widespread use of LED lighting and the screens of devices such as smartphones and computers, humans are exposed to ever-increasing amounts of light in the blue spectrum because commonly used LEDs emit a high fraction of blue light.

Blue light is the highest energy in the visible light band, and in the spectrum it is right next to ultraviolet, which has beneficial effects for humans but many harmful effects. . Artificial blue light is the one that can best trick our metabolism into behaving as if it were daytime. Cheating can be beneficial if it serves to fight jet lag and get us used to a new sleep schedule, or harmful if it disrupts the schedule we should be following.

LED lighting, even in the most developed countries, has not been used long enough to know its effects on a typical human lifespan. Concerns are growing that prolonged exposure to artificial light, especially blue-enriched LED light, may be detrimental to human health. Although the full effects of very long exposure to blue light in humans are not yet known, the accelerated aging observed in short-lived model organisms should alert us to the potential cellular damage that blue light can provoke.

Flies exposed to blue light. (Photo: Oregon State University College of Science)

In previous research, the team of Jaga Giebultowicz from Oregon State University in the United States showed that prolonged exposure to blue light shortened the lifespan of flies, whether they could see it or not.

The results of a new study by Giebultowicz and colleagues suggest that the harmful effects of blue light exposure for longer than normal natural light exposure are compounded as a person ages.

Among the main domestic emitters of artificial blue light are computer screens, MOBILE phone screens and LED lamps.

The new study was conducted on flies of the species Drosophila melanogaster, an important model organism for cellular and developmental mechanisms that it shares with other animals and humans. The experiment looked at the survival rate of flies kept in the dark and then moved at progressively older ages to an environment of constant blue light from light-emitting diodes, or LEDs.

The transition from dark to light occurred at 2, 2, 40 and 60 days of age.

The study paid particular attention to the effects of blue light on the mitochondria of fly cells.

Mitochondria act as the powerhouse of the cell, generating adenosine triphosphate, or ATP, a source of chemical energy.

The study results indicate that chronic exposure to blue light can impair energy-producing pathways even in cells that are not specialized to sense light. Giebultowicz and his colleagues found that while some responses in the mitochondria decreased with age, independent of blue light, others decreased, especially with greater exposure to blue light.

And the new study also shows a worsening of the harmful effects of blue light as the age of the subject increases. In other words, harmful exposure to blue light increases the older the individual.

In previous research, flies subjected to daily cycles of 12 hours in light and 12 hours in darkness had shorter lifespans compared to flies kept in total darkness or those kept under a light with filtered blue wavelengths.

Flies exposed to blue light showed damage to retinal cells and brain neurons and had problems with locomotion: the flies’ ability to climb the walls of their enclosures, a common behavior, was impaired.

Some of the flies in the experiment were mutants that had not developed eyes, and even these eyeless flies exhibited deficiencies under blue light, suggesting that seeing light was not a requirement for the flies. flies don’t have to see the light to be hurt.

The new study is titled “Age-dependent effects of blue light exposure on lifespan, neurodegeneration, and mitochondrial physiology in Drosophila melanogaster.” And it was published in the academic journal npj Aging. (Character font: NCYT by Amazings)