The harmful effects of daily and lifelong exposure to blue light emanating from phones, computers and home accessories worsen as a person ages, new research from Oregon State University suggests.
The study, published today in Nature Partner Journals Aging, involved Drosophila melanogaster, the common fruit fly, an important model organism for the cellular and developmental mechanisms it shares with other animals and humans.
Jaga Giebultowicz, an OSU College of Science researcher who studies biological clocks, led a collaboration that examined the survival rate of flies kept in the dark and then moved at progressively older ages to a of constant blue light from light-emitting diodes, or LEDs.
Dark-to-light transitions occurred at two, 20, 40 and 60 days, and the study involved the effect of blue light on the mitochondria of the flies’ cells.
Mitochondria act as a cell’s powerhouse, generating adenosine triphosphate, or ATP, a source of chemical energy.
In previous research, Giebultowicz showed that prolonged exposure to blue light affected the longevity of flies, regardless of whether it was shining in their eyes.
The new aspect of this new study is showing that chronic exposure to blue light can impair energy production pathways even in cells that are not specialized to detect light. We determined that mitochondria-specific reactions were dramatically reduced by blue light, while other reactions were reduced by age independent of blue light. You can think of it as blue light exposure adding insult to injury in aging flies.”
Jaga Giebultowicz, researcher, OSU College of Science
Collaborating with Giebultowicz on the work, partially funded by the National Institutes of Health, were Yujuan Song, Jun Yang and David Hendrix of OSU’s College of Science, Matthew Robinson of the College of Public Health and Human Sciences, and Alexander Law and Doris Kretzschmar. from Oregon Health and Science University.
Scientists note that natural light is crucial to a person’s circadian rhythm: the 24-hour cycle of physiological processes such as brain wave activity, hormone production and cell regeneration that are important factors in eating and sleeping patterns.
But there is evidence to suggest that increased exposure to artificial light is a risk factor for sleep and circadian disorders, Giebultowicz said. And with the predominant use of LED lighting and device displays, humans are exposed to increasing amounts of light in the blue spectrum, as commonly used LEDs emit a large fraction of blue light.
“This technology, LED lighting, even in most developed countries, has not been used long enough to know its effects over the course of human life,” he said. “There is growing concern that prolonged exposure to artificial light, especially blue-enriched LED light, may be harmful to human health. While the full effects of blue light exposure over the life, not yet known in humans, accelerated aging is observed in the short term. The living model organism should alert us to the potential for cellular damage from this stressor.”
In the meantime, there are some things people can do to help themselves that don’t involve sitting for hours in the dark, researchers say. Glasses with amber lenses will filter blue light and protect your retinas. And phones, laptops and other devices can be set to block blue emissions.
“Our previous work showed that lifetime daily exposure to blue light, but not other visible wavelengths, has deleterious effects on the brain, motor skills and lifespan of the model organism ” said Giebultowicz. “We are now reporting that the harmful effects of blue light on flies are highly age-dependent: the same duration of exposure to the same light intensity decreases lifespan and increases neurodegeneration more significantly in old flies than in young women”.
In previous research, flies subjected to daily cycles of 12 hours in the light and 12 hours in the dark had shorter lifespans compared to flies kept in complete darkness or kept in the light for lengths of filtered blue waves.
Flies exposed to blue light showed damage to their retinal cells and brain neurons and had impaired locomotion: the flies’ ability to climb the walls of their enclosures, a common behavior, was reduced.
Some of the flies in the experiment were mutants that did not develop eyes, and even those flies without eyes showed impairment, suggesting that the flies did not need to see light to be harmed.
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Journal reference:
Song, Y. et al. (2022) Age-dependent effects of blue light exposure on lifespan, neurodegeneration and mitochondrial physiology in Drosophila melanogaster. npj Aging. doi.org/10.1038/s41514-022-00092-z.