Daily exposure to blue light may accelerate aging, study says

Prolonged exposure to blue light, which emanates from phones, computers, and household fixtures, could affect longevity, even if it's not shining in an individual’s eyes, according to a new study by researchers at Oregon State University  in Corvallis and published in the journal Aging and Mechanisms of Disease.

The study involved a widely used organism, Drosophila melanogaster, the common fruit fly, an important model organism because of the cellular and developmental mechanisms it shares with other animals and humans.

Researchers led by Jaga Giebultowicz, PhD, examined how flies responded to daily 12-hour exposures to blue LED light, similar to the prevalent blue wavelength in devices like phones and tablets, and found that the light accelerated aging.

Flies subjected to daily cycles of 12 hours in light and 12 hours in darkness had shorter lives compared to flies kept in total darkness or those kept in light with the blue wavelengths filtered out. The flies exposed to blue light showed damage to their retinal cells and brain neurons and had impaired locomotion, and the flies' ability to climb the walls of their enclosures, a common behavior, was diminished.

Some of the flies in the experiment were mutants that do not develop eyes, and those eyeless flies displayed brain damage and locomotion impairments, suggesting flies didn't have to see the light to be harmed by it.

"The fact that the light was accelerating aging in the flies was very surprising to us at first," said Giebultowicz. "We'd measured expression of some genes in old flies, and found that stress-response, protective genes were expressed if flies were kept in light. We hypothesized that light was regulating those genes. Then we started asking, what is it in the light that is harmful to them, and we looked at the spectrum of light. It was very clear cut that although light without blue slightly shortened their lifespan, just blue light alone shortened their lifespan very dramatically."

Natural light, Giebultowicz said, is crucial for the body'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 feeding and sleeping patterns.

"But there is evidence suggesting that increased exposure to artificial light is a risk factor for sleep and circadian disorders," she said. "And with the prevalent use of LED lighting and device displays, humans are subjected to increasing amounts of light in the blue spectrum since commonly used LEDs emit a high fraction of blue light. But this technology, LED lighting, even in most developed countries, has not been used long enough to know its effects across the human lifespan."

Giebultowicz says that the flies, if given a choice, avoid blue light. Further, there are a few things people can do to help themselves that don't involve sitting for hours in darkness, the researchers said. Eyeglasses with amber lenses will filter out the blue light and protect the retinas. And phones, laptops, and other devices can be set to block blue emissions.