Too much screen use has been linked to obesity and psychological problems. A newly reported study in fruit flies by researchers at Oregon State University now suggests that basic cellular functions could be impacted by the blue light (BL) emitted by these devices and other sources of artificial light. The results showed that accelerated aging seen in Drosophila kept in blue light was linked with changes to pathways involved in energy and amino acid metabolism, and with changes to levels of several brain neurotransmitters.
“Excessive exposure to blue light from everyday devices, such as TVs, laptops, and phones, may have detrimental effects on a wide range of cells in our body, from skin and fat cells, to sensory neurons,” said Jadwiga Giebultowicz, PhD, a professor at the Department of Integrative Biology at Oregon State University. “We are the first to show that the levels of specific metabolites—chemicals that are essential for cells to function correctly—are altered in fruit flies exposed to blue light. Our study suggests that avoidance of excessive blue light exposure may be a good anti-aging strategy.”
Giebultowicz is senior author of the team’s published paper in Frontiers in Aging, which is titled “Chronic blue light leads to accelerated aging in Drosophila by impairing energy metabolism and neurotransmitter levels,” in which they concluded that their collective data “provide novel insights into the mechanisms by which BL interferes with vital metabolic pathways that are conserved between fly and human cells.”
Blue light (BL) is increasingly common in artificial lighting—such as light-emitting diodes— to which we are all becoming increasingly exposed, “raising concerns about its potential health hazard to humans,” the authors wrote. Evidence is mounting that BL has the potential to damage human eyes and contribute to diseases including glaucoma, retinal degeneration and age-related maculopathy. Recent studies have also suggested that blue light may be damaging at an organismal level. “… recent data on the model organisms C, elegans and D. melanogaster demonstrate that cells and tissues not specialized for light perception, such as brain, can be damaged in flies kept in BL for extended time,” they wrote. “For example, visible light, especially in the blue region, causes oxidative stress and shortens the lifespan of the nematode C. elegans. Further, adult Drosophila exposed to 12 h of BL per day show symptoms of accelerated aging including impaired locomotor performance, brain neurodegeneration, and reduced lifespan compared to flies reared in constant darkness or LED light with blue wavelengths filtered out.”
The researchers at Oregon State University previously showed that fruit flies exposed to light turn on stress protective genes, and that those kept in constant darkness lived longer. “To understand why high-energy blue light is responsible for accelerating aging in fruit flies, we compared the levels of metabolites in flies exposed to blue light for two weeks to those kept in complete darkness,” said Giebultowicz. The authors further explained, “… we investigated effects of chronic BL on metabolic pathways in heads of flies with genetically ablated eyes in order to focus on extra-retinal tissues.”
The results showed that blue light exposure caused significant differences in the levels of metabolites measured by the researchers in the cells of fly heads. “… dramatic metabolic rearrangements are observed in heads of flies kept in BL for 14 days,” The investigators stated. “Several of the metabolites that were significantly reduced in BL-exposed flies play important roles in metabolic homeostasis.” In particular, they found that the levels of the metabolite succinate were increased, but glutamate levels were lowered. “Succinate is essential for producing the fuel for the function and growth of each cell. High levels of succinate after exposure to blue light can be compared to gas being in the pump but not getting into the car,” said Giebultowicz.
The changes recorded by the researchers suggest that the cells are operating at suboptimal level, and this may cause their premature death, and further, explain the previous findings that blue light accelerates aging. “Our metabolomics analyses revealed alterations in the levels of several metabolites suggesting that energy production and other cellular pathways are significantly altered in these flies,” the authors commented.
Another “troubling discovery,” Giebultowicz stated, was the blue light exposure-related reductions in molecules responsible for communication between neurons. “One of the important findings in our metabolite analysis is the apparent imbalance in the levels of neurotransmitters in brains of flies held in BL for 14 days, which showed significant brain neurodegeneration,” the authors reported. “… our analysis detected significantly reduced levels of several neurotransmitters including glutamate and gamma-aminobutyric acid (GABA), suggesting that BL disrupts brain homeostasis.”
“LEDs have become the main illumination in display screens such as phones, desktops and TVs, as well as ambient lighting, so humans in advanced societies are exposed to blue light through LED lighting during most of their waking hours,” Giebultowicz continued. “The signaling chemicals in the cells of flies and humans are the same, so the there is potential for negative effects of blue light on humans.”
It’s hoped that future research will investigate the effects of blue light directly on human cells. “We used a fairly strong blue light on the flies—humans are exposed to less intense light, so cellular damage may be less dramatic,” Giebultowicz noted. “The results from this study suggests that future research involving human cells is needed to establish the extent to which human cells may show similar changes in metabolites involved in energy production in response to excessive exposure to blue light.”
Noting some limitations to their study, the authors nevertheless concluded, “In summary, our metabolomic results provide novel insights into the mechanisms by which BL interferes with vital metabolic pathways in extra-retinal cells in flies. All metabolites altered by BL in our study are conserved between fly and human cells. Therefore, it is possible that prolonged exposure to BL may have similar, albeit more subtle effects on skin, subcutaneous fat, and other cells in the human.”