Red light, blue light: Illuminating a few health claims – Part 1

By: Jacob Van Oorschot, Contributing Writer

Cover Image: Reno Zhu, Illustrator (original work)

Among the greatest challenges I faced in my otherwise charmed childhood was in falling asleep. One ploy my tweenage self used to try to address this issue involved putting a red pillowcase over the lamp beside my bed when I read before going to sleep. The goal was not only to dim the light, but specifically to reduce the amount of blue light I was seeing—in effect, a crude blue light filter. I think I might have been ahead of the curve on this one; blue light filters are all the rage now for our phones, computers, and even glasses. In addition to disrupting circadian rhythm, blue light stands accused of contributing to eyestrain and aging the skin.

I want to begin by addressing the alleged disruption of circadian rhythm, as it is the substantive accusation against blue light. To form an image, visible light is sensed by photoreceptor cells in the eye called rods and cones using proteins called opsins. When opsins in photoreceptor cells absorb light, a chemical signal is produced, ultimately sent to the brain via the optic nerve. Scientists have also discovered a third type of photoreceptor cell, called ipRGCs. These cells have their own opsin protein, melanopsin, that responds selectively to blue light. However, they don’t contribute to vision. Instead, one of their roles is in controlling circadian rhythm. When they sense blue light, they suppress the release of melatonin (1), a crucial hormone for sleep onset. This mechanistic understanding is backed up in real life by studies that find exposure to blue light from electronic screens delays sleep, and blocking blue light from these devices can reverse the effect (2). (While all visible light suppresses melatonin secretion to some degree, blue light has a stronger effect.)

It is clear that blue light entering the eyes can and will disrupt sleep. In contrast, evidence that blue light causes eyestrain is more tenuous. Sure, eyestrain caused by digital screens is a common phenomenon, and digital screens produce blue light. But it’s unclear that blue light itself is the problem. Studies on the effect of filtering out blue light from digital screens as an intervention against eyestrain have mixed findings (2). Instead, experts suggest other factors could be causing eyestrain, like contrasting brightness between a screen and its surroundings, glare, and reading proximity (3).

I’ve  also begun to hear recently that blue light could be bad for your skin, too, causing collagen breakdown, “aging,” and wrinkles (4). While blue light is lower in energy than UV (which we know can damage skin), blue light penetrates deeper into the skin, and we also get more exposure to it. In fact, there is much more blue light than UV in the sun’s radiation, and a good chunk of artificial light and consumer electronics light is blue (1). Blue light sits right beside UV on the electromagnetic spectrum, and the division between them is somewhat arbitrary, so it is plausible that blue light could have similar detrimental effects as UV on the skin. So, what are these detrimental effects?

UV is classified into lower-energy UVA and higher-energy UVB, both of which have harmful effects on our cells. UVB causes harm by directly damaging DNA, causing mutations that can lead to cancer (1). In contrast, UVA damages skin with through a different and less direct mechanism. When UVA hits the skin, it is absorbed by molecules called chromophores, and this process creates reactive oxygen species (ROS). Oxidative stress, caused by excessive amounts of ROS, can cause the release of inflammatory cytokines, as well as breakdown of the collagen-based extracellular matrix between cells. These effects will not directly cause cancer, but could lead to premature skin aging (1).

Is there any evidence that blue light can damage skin through these pathways? Well, our skin does contain some chromophores that generate ROS in response to blue light, such as cryptochromes and cytochrome c oxidase (1). As such, there is a mechanistic basis for blue light harming skin in similar ways to UVA. Cell culture studies support this theory (1, 5). 

So is blue light from your phone and computer aging your skin? I don’t think so, because as with many things, the dose makes the poison. First of all, your screens and indoor lighting are probably not the problem. Your puny phone screen and weak computer monitor are sending orders of magnitude less blue light into your skin that the sun does (1). Even if you’re spending all day in front of them, the total dose will be less than that from a couple hours in the sun. While the blue light from your phone before bed is enough to disrupt your sleep, its intensity pales in comparison to the blue light exposure your skin gets throughout the day.

Indoor lighting, too, is weaker than bright sun. However, blue light exposure from the sun is a reasonable concern. Typical modern sunscreens use specialized filters that absorb only UV light, letting most visible light through. If you think about it, invisible sunscreen probably isn’t interacting with visible light; otherwise it would change your apparent skin tone! So, some companies make tinted sunscreens to block visible light in addition to UV (6). When I’m in the sun I predominantly use old school mineral sunscreen, which blocks some blue light (1), along with clothes and a hat,  so I’m not too worried about blue light. 

If you remain concerned about blue light, though, you should keep in mind that blue light isn’t all bad. For example, intense blue light killsC. acnes, a bacteria that causes acne (1). Blue light is also used to treat inflammatory skin disorders because it can modulate the immune system (1). These clinical effects are dose dependent, though, so day-to-day blue light exposure will not necessarily bring them about. Nevertheless, I try to remember that over the course of our evolution, we probably got lots of sun exposure, and a moderate amount is likely to come with positives. While UVB causes skin cancer, it is also necessary for the production of Vitamin D in the skin. So perhaps our body takes advantage of visible light exposure in more subtle ways, too. And beyond skin effects, I sit in front of a bright blue-white light every morning in the winter because this can help with mood problems brought on by shorter day-length in the winter (7).

This is only half of the story, though. Next time, I want to shine light on the supposed health effects of red and infrared light at the other end of the visible light spectrum. Will they prove to be positive, negative, or ultimately inconsequential?

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References

1. Schutz R. 2021. Blue Light and the Skin, p. 354–373. In Challenges in Sun Protection. Karger, Switzerland. 
2. Rosenfield M. 2019. Living With Blue Light: The sun is your biggest enemy, and digital devices aren’t as bad as you think. Here’s the current research and recommendations. 
3. Huffman J. 2024. Computers, Digital Devices, and Eye Strain. American Academy of Ophthalmology. https://www.aao.org/eye-health/tips-prevention/computer-usage. Retrieved 7 January 2026. 
4. Kumari J, Das K, Babaei M, Rokni GR, Goldust M. 2023. The impact of blue light and digital screens on the skin. Journal of Cosmetic Dermatology 22:1185–1190. 
5. Dong K, Goyarts EC, Pelle E, Trivero J, Pernodet N. 2019. Blue light disrupts the circadian rhythm and create damage in skin cells. International Journal of Cosmetic Science 41:558–562. 
6. Nathan N, Manstein D. 2020. Tinted sunscreens: Benefits beyond an attractive glow. Harvard Health. https://www.health.harvard.edu/blog/tinted-sunscreens-benefits-beyond-an-attractive-glow-2020071320534. Retrieved 8 January 2026. 
7. Melrose S. 2015. Seasonal Affective Disorder: An Overview of Assessment and Treatment Approaches. Depression Research and Treatment 2015:178564. 
8. Whelan HT, Smits RL, Buchman EV, Whelan NT, Turner SG, Margolis DA, Cevenini V, Stinson H, Ignatius R, Martin T, Cwiklinski J, Philippi AF, Graf WR, Hodgson B, Gould L, Kane M, Chen G, Caviness J. 2001. Effect of NASA Light-Emitting Diode Irradiation on Wound Healing. Journal of Clinical Laser Medicine & Surgery 19:305–314. 
9. Yadav A, Gupta A. 2017. Noninvasive red and near-infrared wavelength-induced photobiomodulation: promoting impaired cutaneous wound healing. Photodermatology, Photoimmunology & Photomedicine 33:4–13. 
10. Erdle BJ, Brouxhon S, Kaplan M, Vanbuskirk J, Pentland AP. 2008. Effects of Continuous-Wave (670-nm) Red Light on Wound Healing. Dermatologic Surgery 34:320. 
11. Kuffler DP. 2016. Photobiomodulation in Promoting Wound Healing: A Review. Regenerative Medicine 11:107–122. 
12. Barolet D. 2021. Near Infrared Light and the Skin: Why Intensity Matters, p. 374–384. In Challenges in Sun Protection. Karger, Switzerland. 
13. Couturaud V, Le Fur M, Pelletier M, Granotier F. 2023. Reverse skin aging signs by red light photobiomodulation. Skin Res Technol 29:e13391. 
14. Keszler A, Lindemer B, Broeckel G, Weihrauch D, Gao Y, Lohr NL. 2022. In Vivo Characterization of a Red Light-Activated Vasodilation: A Photobiomodulation Study. Front Physiol 13. 
15. Rayegani SM, Raeissadat SA, Heidari S, Moradi-Joo M. 2017. Safety and Effectiveness of Low-Level Laser Therapy in Patients With Knee Osteoarthritis: A Systematic Review and Meta-analysis. J Lasers Med Sci 8:S12–S19. 16. Maiorana A, O’Driscoll G, Taylor R, Green D. 2003. Exercise and the Nitric Oxide Vasodilator System. Sports Med 33:1013–1035.

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