In this study, researchers attempt to determine how exposure to blue light affects the health of flies.
Artificial lights – such as blue light from LED displays – are associated with affecting sleep patterns and contributing to the incidence of sleep disorders. With many modern tools using artificial lights, it is imperative to study the long-term effects of these lights on human health, which is something that is currently unknown. In some organisms, such as flies (Drosophila) and mice, these blue lights have been shown to be detrimental. Blue light exposure is associated with damage in the retina of both organisms and contributes to a shorter lifespan in flies.
To further try to understand this mechanism, researchers sought to examine how artificial light affects the well-being of flies. The researchers created two groups of flies. One group had exposure to artificial light for 12 hours, then darkness for the other 12 hours. The other group would have the full 24 hours of darkness. The researchers found that those in darkness survived longer than those in the 12-hour white light cycle. Seeing these results in white light then prompted them to attempt a similar experiment with blue light.
Blue light reduces the life span of flies
The median lifespan of flies exposed to blue light was reduced by about 50% and 30% in another type of flies. Further experiments suggested that this may have something to do with the process of phototransduction. They also found that a functional circadian clock has no significant effect in protecting the flies against any of the damage blue-light may do.
The researchers also examined the retinal cells of the flies who had exposure to blue light and found that there was more damage to these cells compared to those who lived in darkness. In additional experiments, they determined that exposure to blue light seems to also be associated with brain damage in the flies.
In sequencing experiments, they found that there were different patterns of gene expression between the blue light and darkness-exposed flies. For example, there was an increase in the expression of heat-shock proteins in the blue light-exposed flies. As the flies got older, the effect of the blue light on the expression of stress genes and its other effects (such as increased mortality) seemed to become more prominent. Frequency of the exposure to blue light also plays a role in the detrimental effects of blue light on flies.
Overall, the researchers were able to show that blue light negatively affects fly aging. The light causes eye and brain damage, and can contribute to early mortality. Age and frequency of exposure may also affect how intense these effects may be.
The authors note that in order to determine the mechanism responsible for this damage and mortality, more studies are needed. The authors also stated that other organs of the fly need to be examined to see if the effects of blue light exposure are not just limited to what was seen ini this study. This may prove to be useful in understanding the effect of blue light on long-term human health.
Written by Olajumoke Marissa Ologundudu, B.Sc. (Hons)
Nash et al. Daily blue-light exposure shortens lifespan and causes brain neurodegeneration in Drosophila. npj Aging and Mechanisms of Disease. 2019;5:8. doi: https://doi.org/10.1038/s41514-019-0038-6
Image by fancycrave1 from Pixabay