Avoiding blue light exposure for a healthier lifespan
Image credit: Nash et al. 2019 https://www.nature.com/articles/s41514-019-0038-6#Fig2
Jamila Dec 10, 2020
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Avoiding blue light exposure for a healthier lifespan.
Nash reported that daily exposure to blue light reduced the lifespan of Drosophila and induced neurodegeneration. In the study, flies exposed to 12 hours of blue light and 12 hours of darkness (B:D) had reduced lifespans than flies kept in full darkness (D:D) and flies kept in the blue light but with a blue light filter (W–B:D). Furthermore, there were signs of retinal cell damage and impaired locomotion in the flies exposed to blue light. Therefore, daily blue light exposure advanced aging in the flies. The impact of blue light on lifespan was not sex-specific as females and males were equally impacted.
Due to Nash's study, I'm wondering whether the same phenomenon could be seen in humans. We already know that blue light can disrupt the circadian rhythm, and thus sleep in humans but does it also impact our lifespan too? I know humans are far more complex than flies, but it would be interesting to explore this.
If blue light does impact the human lifespan, then technology would change. People would want laptops and phones without blue light or use blue light filters. Many people are already using blue light filters to get better sleep at night time.
Future ideas
Does blue light exposure reduce the human lifespan?
Researchers should determine whether those exposed to blue light are more prone to age-related diseases like diabetes and Alzheimer's?
We are surrounded by technology emitting blue light in this day and age, like our phones and laptops. A comparison should be made between people exposed to blue light and those that use a blue light filter! Are there any differences in their health?
What do you think? Have you got any further ideas?
[1]Nash, Trevor R., et al. "Daily blue-light exposure shortens lifespan and causes brain neurodegeneration in Drosophila." npj Aging and Mechanisms of Disease 5.1 (2019): 1-8.
[2]Zerbini, Giulia, Thomas Kantermann, and Martha Merrow. "Strategies to decrease social jetlag: Reducing evening blue light advances sleep and melatonin." European Journal of Neuroscience (2018).
Not only have researchers confirmed that long-term exposure to blue light can speed up ageing (figure below), but they found the underlying mechanisms behind it. They compared metabolites in Drosophila exposed to blue light with the ones kept in darkness (very similar to the paper Jamila cited). Two metabolites came out as the most important - succinate and glutamate. Levels of succinate, a molecular fuel, were increased, meaning the metabolism was faster, leading to increased cell exhaustion and stress. On the other hand, glutamate is known to be a key constituent of GABA, which acts as an anti-stress neurotransmitter. Its levels in Drosophila exposed to blue light were reduced, leading to reduced stress control.
Another important aspect of the study was a comparison of Drosophila metabolites with humans. The highlighted metabolites have the same function in humans and could therefore be compared. Blue light levels were of high intensity, but considering the short lifespan of flies (3 months), the amount of light could be similar to decades of exposure in humans.
Hi Jamila! Nice idea! We heard many times that specialists recommend using glasses blocking the blue light when using computers. Also, as you said, it's getting more and more popular to use the "night light", which reduces the blue light and makes the screen seem yellowish.
What I think is that blue light CAN'T DIRECTLY influence human longevity/aging just because there is (still) no clear definition of the aging phenotype (https://brainstorming.com/sessions/defining-the-aging-phenotype/14). Aging is a progressive time-consuming process that is a result of many small changes. As we are keen on believing in the things we "see", we rather focus on these smaller, short-term changes (diabetes, osteoporosis, skin diseases, macular degeneration, Alzheimer's, ...). Therefore, it's hard to directly correlate "aging and longevity" to the blue light exposure (please, correct me if I am wrong).
But, at the level we are now, many interesting "INDIRECT" correlations can be found between blue light and longevity if we look at how blue light affects some of these short-term changes.
For example, the research on Drosophila you mentioned above proved that blue light affects its lifespan. It also proved that even flies that did not have eyes developed the same locomotion impairments and brain damage, the same as the other ones. In further research, they observed changes in stress-response mechanisms in flies exposed to light. It's also interesting that if given a choice, flies would tend to avoid blue light. This all gives enough room for further research on blue light.
Consequently, I am thrilled that blue light effects do not necessarily mean vision and the general body's circadian rhythm disbalance leading to general changes in the organism defined as aging. Recent research described through plenty of experiments that direct exposure of the skin to the blue light caused wrinkles, worsening skin laxity, and hyperpigmentation. Skin cells also have their own circadian rhythm and are known to repair the damage during the night. If the fine-tuned rhythm of repair mechanisms is changed, reactive oxygen species are generated in larger quantities, which leads to DNA damage that is not routinely repaired, thereby causing inflammation and the breakdown of healthy collagen and elastin (https://www.allure.com/story/blue-light-phone-skin-effects, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4337113/).
So yes, in light of the "new" perception of aging as a cumulative set of diseases, I would dare say that blue light DIRECTLY affects aging through multiple mechanisms that lead to age-related diseases. These mechanisms could be:
1. The general disbalance of circadian rhythm, affecting the sleep time and body homeostasis, slowly leading towards the mentioned "shorter-term" changes
2. The increased rate of DNA damage through the mechanisms similar to sun exposure
3. The alterations of skin cells' circadian rhythm, thus affecting skin damage-repair mechanisms, leading to skin aging-associated changes
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Jamila 4 years ago
Hi Juran K.
Thanks for the comment.
The fact that the flies without eyes also developed brain damage and locomotive impairments is quite fascinating. I’m guessing the blue light is absorbed by the skin, and from there, it causes damage in the flies’ bodies by mechanisms that remain to be elucidated. As you mention, it could be due to DNA damage by sun exposure, dysfunction in the circadian rhythm, or a combination of things.
If the effects of blue light exposure are independent of retinal damage and the skin absorbs it, then glasses with a blue light filter might not be helpful. A blue light filter on the light source itself might help more.
I think it would be great to see whether blue light exposure can impact the aging hallmarks in various experimental models:
-Does blue light exposure increase the number of senescent cells in the body?
-Can blue light exposure reduce telomere length?
-Does blue light exposure accelerate the epigenetic age?
-Can blue light exposure cause genomic instability? Etc.
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jnikola4 years ago
Jamila Nice conclusion. The filters on the screen are much more logical then.
For me, it sounds like a series of very simple experiments, analyzing the crucial factors for each of the hallmarks after the blue light exposure (even just on a cellular level). Let's hope someone does it soon :)
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Jamila 4 years ago
Juran K. I know, right! I definitely want to see some results now because the research is so interesting! 😀