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Red Light Therapy: More Than a TikTok Trend?



It was all an accident.


In 1967, Hungarian physician Endre Mester was trying to replicate a US experiment in which the recently invented ruby laser was used to destroy cancerous tumors in rats. Dr. Mester's custom-made laser didn't appear to have any anticancer effect, as it wasn't powerful enough. Very interestingly, however, it seemed to promote hair growth and wound healing in his rats [1].


Just like that, Dr. Mester’s serendipitous discovery would give rise to the first application of low-intensity Red Light Therapy.


Over the next two decades, Dr. Mester, along with his sons, dedicated his career to this new line of research, studying the clinical potential of Red Light Therapy in 15 biological systems. And in 1971, he started using this innovative therapy to treat patients with non-healing ulcers [2].


In the 1990s, another happy accident triggered a new chapter in the history of Red Light Therapy — this time in NASA. As NASA explored the use of red light to grow plants in space, scientists noticed that their wounds healed faster. They conducted studies on Navy SEALs and found Red Light Therapy to improve the healing of training injuries by 40% [3]. Filled with promise, one of the leaders of this research, Dr. Harry T Whelan, was then quoted to say [4]:


"After years of poison (pills) and knives (surgery) in medicine, wouldn't it be nice to have something gentle, like light, to heal?”

From there, Red Light Therapy grew into a hot topic in biomedical research, with proponents studying more of its clinical use cases and critics highlighting the gaps in evidence. 


But, neither could have predicted that their eyes would ever come across the words:


“Red light therapy is that girl.”

That, ladies and gents, is the TikTok effect in full swing. Indeed, TikTok and other social media platforms have taken Red Light Therapy to the mainstream in the last couple of years. Just a few days ago, Riverdale star Pauline Reinhart proclaimed Red Light Therapy her "new best friend" to her six million followers on TikTok.



It’s clear that Red Light Therapy’s meteoric rise has also led to a wave of misuse and misconceptions, especially when it comes to the research behind it. So in this article, we aim to cut through the noise and provide a comprehensive, yet digestible, breakdown of the science of Red Light Therapy.


What Exactly Is Red Light Therapy?


Red Light Therapy, a type of what’s known as Photobiomodulation in scientific circles, is a non-invasive therapeutic technique that uses low-power light in the red and near-infrared spectrum. The wavelengths used for Photobiomodulation range between 600nm and 1000nm, and the therapy is thought to treat various pathologies and repair tissue [5].


The light source for this therapy can be a laser or an LED. The application methods are diverse, including masks, wands, panels, full-body booths, and even intravascular applications [6].


The therapy works at the cellular level. With relatively long wavelengths, the light is thought to reach the mitochondria, the energy-producing components of our cells. Here, red light interacts with a specific protein in the mitochondria’s energy production pathway, potentially enhancing the production of ATP, the universal energy source for all living cells [7]. Increase in ATP provides us with more energy for all the reactions that take place in our bodies.


Additionally, Red Light Therapy is believed to decrease the production of reactive oxygen species in our immune cells [8]. These molecules, when produced in excess, can cause significant damage to the DNA and proteins of neighboring cells.


The State of Red Light Therapy Research


When critics voice concerns about the lack of research on Red Light Therapy, it’s not the quantity of studies they question. In fact, Red Light Therapy has been studied for almost 70 medical conditions [9]. The concern lies in the type of studies conducted. Many of these studies were performed on animals or isolated human cells, which don’t directly translate into clinical practice.


What’s needed are randomized clinical trials, the gold standard in medical research. As of 2022, over 400 such trials investigating Red Light Therapy were conducted [7]. However, many of these trials yielded negative results. Some scientists attribute this to variations in study designs and the parameters of Red Light Therapy application, such as wavelength, intensity, and duration [1].


That said, some studies do show positive results for Red Light Therapy across various medical uses. In the following sections, we’ll delve into the medical uses where Red Light Therapy is growing into standard practice, as well as emerging areas of application. 


Red Light Therapy and Skin Conditions


Given its popularity on TikTok, it’s no surprise that Red Light Therapy has found its most success in skincare.


Acne is one area where Red Light Therapy has been extensively studied. A randomized controlled trial involving 107 patients with mild to moderate acne vulgaris found that a combination of blue and red light, delivered by fluorescent lamps, led to a significant improvement. For inflammatory lesions, this combination even outperformed benzoyl peroxide, a standard acne treatment [10]. However, a systematic review of 25 clinical trials calls for more studies, as existing data is limited by short follow-up times and the exclusion of severe acne cases [11].


Red Light Therapy has also shown promise in skin rejuvenation. In one clinical trial, subjects experienced significant improvements in skin complexion, skin feeling, and skin roughness, along with an increase in collagen density [12].


Psoriasis, a chronic skin condition, could potentially be managed with Red Light Therapy. A pilot study showed improvement in subjects, suggesting Red Light Therapy as a potential treatment option [13].


Burn scars, particularly in children, have also been studied in relation to Red Light Therapy. A randomized controlled study involving 15 children showed significant improvement in the group who underwent Red Light Therapy, with no side effects reported. [14]


Lastly, case reports have indicated the potential of Red Light Therapy in treating rosacea, a chronic inflammatory skin disease [15].


Red Light Therapy and Alopecia


Remember how the first therapeutic effect observed for Red Light Therapy was hair regrowth in Dr. Mester's lab rats? Well, naturally, that makes Androgenetic alopecia, the most common form of hair loss, another area where Red Light Therapy is being studied.


In a clinical trial involving 41 patients with androgenetic alopecia, 22 received Red Light Therapy. The primary endpoint was the percent increase in hair counts from baseline. The treatment group demonstrated a significant 39% increase in hair count [16].


Further supporting the potential of Red Light Therapy in treating alopecia, a meta-analysis of 11 clinical trials reported its effectiveness. The analysis suggested that a low frequency of treatment, less than 60 minutes per week, was more efficacious [17].


However, it’s important to note that 9 of the 11 randomized controlled trials included in the meta-analysis were manufacturer-funded. This has led to criticism of Red Light Therapy due to concerns of bias and conflicts of interest, as most of the large studies are funded by businesses.


Red Light Therapy and Inflammatory Disease


Inflammation is the body's natural response to injury or infection, a protective measure that involves immune cells, blood vessels, and molecular mediators. However, when inflammation persists longer than necessary, it can lead to chronic inflammatory diseases.


One such condition is knee osteoarthritis, the most common joint disease. In an uncontrolled trial, 30 participants received Red Light Therapy combined with exercise. The results indicated that Red Light Therapy reduced pain and improved function in knee osteoarthritis [18].


Similarly, three randomized controlled trials of moderate quality showed significant improvements in pain for patients with rheumatoid arthritis, another inflammatory disease, following Red Light Therapy treatment [19].


Red Light Therapy has also been studied in the context of oral mucositis, a painful inflammation and ulceration of the mucous membranes lining the digestive tract, often a side effect of chemotherapy. An uncontrolled trial involving patients with chemotherapy-induced oral mucositis found Red Light Therapy to be effective in alleviating oral mucositis scores [20].


Red Light Therapy and Eye Disorders


As we explore the emerging therapeutic uses of Red Light Therapy, let’s turn our attention to eye-related conditions. Two disorders stand out: short-sightedness in children and age-related macular degeneration.


Short-sightedness, or myopia, is a condition where the eye is longer than normal, causing distant objects to appear blurry. A year-long study found that Red Light Therapy could slightly reduce this length, improving vision in children with myopia [21].


Age-related macular degeneration is a condition that affects the central part of the retina, leading to loss of central vision. It’s a common cause of vision loss in older adults. Encouragingly, both preclinical and clinical studies have shown that Red Light Therapy can be beneficial in treating age-related macular degeneration. This has led to its approval by regulatory bodies like the FDA and EMA for treating intermediate age-related macular degeneration [22].


Red Light Therapy and Depression


Depression, a condition resistant to treatment in over a third of patients, is a key area for innovative research, including studies on Red Light Therapy. Theoretically, transcranial Red Light Therapy can penetrate the cerebral cortex, stimulate the mitochondrial respiratory chain, and significantly increase cerebral blood flow.


In a placebo-controlled randomized trial, Red Light Therapy was delivered to the prefrontal cortex of subjects diagnosed with Major Depressive Disorder. Administered twice a week for six weeks, Red Light Therapy was found to be efficacious, although the optimal dose remains undefined [23].


Further supporting these findings, a meta-analysis of clinical trials concluded that Red Light Therapy is effective in reducing depression symptoms [24].


Red Light Therapy and Aging


Earlier, we discussed Red Light Therapy for skin rejuvenation. But, in a world that longs for longevity, Red Light Therapy could offer hope against whole-body aging.


The most compelling evidence lies in brain aging. Human studies have demonstrated the promising metabolic effects of Red Light Therapy on the brain, improving electrophysiological activity and cognitive functions such as attention, learning, memory, and mood in older individuals [25].


While still in the experimental stage, animal models have shown promise for cardiac aging. Red Light Therapy treatment mitigated age-associated cardiovascular changes, improved neuromuscular coordination, and even increased longevity in a mouse model. These findings hint at the potential of Red Light Therapy in promoting healthy aging [26].


Before You Go


As we conclude, it's important to remember that the promising results of Red Light Therapy we've discussed were obtained in controlled laboratory and clinical settings. Before you consider at-home Red Light Therapy, which comes in a myriad of options with varying wavelengths, intensities, and dose durations, keep this in mind. 


So if your takeaway from this article is that Red Light Therapy is indeed "that girl", it's best to try it out under the supervision of professionals in reputable medical practices.


References: 


[1] Hamblin, M. R. (2016). Photobiomodulation or low-level laser therapy. Journal of Biophotonics, 9(11-12), 1122–1124. https://doi.org/10.1002/jbio.201670113


[2] Mester, E., Szende, B., & Gärtner, P. (1968). [The effect of laser beams on the growth of hair in mice]. Radiobiologia, Radiotherapia, 9(5), 621–626. https://pubmed.ncbi.nlm.nih.gov/5732466/


[3] Whelan, H. T., Smits, R. L., Buchman, E. V., Whelan, N. T., Turner, S. G., Margolis, D. A., Cevenini, V., Stinson, H., Ignatius, R., Martin, T., Cwiklinski, J., Philippi, A. F., Graf, W. R., 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(6), 305–314. https://doi.org/10.1089/104454701753342758


[4] Coulter, A. H. (2003). Let There Be Light - and Healing. Alternative and Complementary Therapies, 9(6), 322–326. https://doi.org/10.1089/107628003322658601


[5] Huang, Y.-Y., Chen, A. C.-H. ., Carroll, J. D., & Hamblin, M. R. (2009). Biphasic Dose Response in Low Level Light Therapy. Dose-Response, 7(4), dose-response.0. https://doi.org/10.2203/dose-response.09-027.hamblin


[6] Chung, H., Dai, T., Sharma, S. K., Huang, Y.-Y., Carroll, J. D., & Hamblin, M. R. (2011). The Nuts and Bolts of Low-level Laser (Light) Therapy. Annals of Biomedical Engineering, 40(2), 516–533. https://doi.org/10.1007/s10439-011-0454-7


[7] Hamblin, M. R. (2022). Photobiomodulation and Light Therapy in Oncology. Springer EBooks, 255–286. https://doi.org/10.1007/978-3-030-86510-8_17


[8] Yuji Fujimaki, Tadashi Shimoyama, Liu, Q., Umeda, T., Nakaji, S., & Sugawara, K. (2003). Low-Level Laser Irradiation Attenuates Production of Reactive Oxygen Species by Human Neutrophils. Journal of Clinical Laser Medicine & Surgery, 21(3), 165–170. https://doi.org/10.1089/104454703321895635


[9] Heiskanen, V., & Hamblin, M. R. (2018). Photobiomodulation: lasers vs. light emitting diodes? Photochemical & Photobiological Sciences, 17(8), 1003–1017. https://doi.org/10.1039/c8pp00176f


[10] Papageorgiou, P., Katsambas, A., & Chu, A. (2000). Phototherapy with blue (415 nm) and red (660 nm) light in the treatment of acne vulgaris. British Journal of Dermatology, 142(5), 973–978. https://doi.org/10.1046/j.1365-2133.2000.03481.x


[11] Hamilton, F. L., Car, J., Lyons, C., Car, M., Layton, A., & Majeed, A. (2009). Laser and other light therapies for the treatment of acne vulgaris: systematic review. British Journal of Dermatology, 160(6), 1273–1285. https://doi.org/10.1111/j.1365-2133.2009.09047.x


[12] Wunsch, A., & Matuschka, K. (2014). A controlled trial to determine the efficacy of red and near-infrared light treatment in patient satisfaction, reduction of fine lines, wrinkles, skin roughness, and intradermal collagen density increase. Photomedicine and Laser Surgery, 32(2), 93–100. https://doi.org/10.1089/pho.2013.3616


[13] Kleinpenning, M. M., Otero, M. E., van Erp, P. E. J., Gerritsen, M. J. P., & van de Kerkhof, P. C. M. (2011). Efficacy of blue light vs. red light in the treatment of psoriasis: a double-blind, randomized comparative study. Journal of the European Academy of Dermatology and Venereology, 26(2), 219–225. https://doi.org/10.1111/j.1468-3083.2011.04039.x


[14] Alsharnoubi, J., Shoukry, K. E.-S., Fawzy, M. W., & Mohamed, O. (2018). Evaluation of scars in children after treatment with low-level laser. Lasers in Medical Science, 33(9), 1991–1995. https://doi.org/10.1007/s10103-018-2572-z


[15] Sorbellini, E., De Padova, M. P., & Rinaldi, F. (2020). Coupled blue and red light-emitting diodes therapy efficacy in patients with rosacea: two case reports. Journal of Medical Case Reports, 14(1). https://doi.org/10.1186/s13256-019-2339-6


[16] Lanzafame, R. J., Blanche, R. R., Bodian, A. B., Chiacchierini, R. P., Fernandez-Obregon, A., & Kazmirek, E. R. (2013). The growth of human scalp hair mediated by visible red light laser and LED sources in males. Lasers in Surgery and Medicine, 45(8), 487–495. https://doi.org/10.1002/lsm.22173


[17] Liu, K.-H., Liu, D., Chen, Y.-T., & Chin, S.-Y. (2019). Comparative effectiveness of low-level laser therapy for adult androgenic alopecia: a system review and meta-analysis of randomized controlled trials. Lasers in Medical Science, 34(6), 1063–1069. https://doi.org/10.1007/s10103-019-02723-6


[18] Ammar, T. A. R. A. (2014). Monochromatic Infrared Photo Energy versus Low Level Laser Therapy in Patients with Knee Osteoarthritis. Journal of Lasers in Medical Sciences, 5(4), 176–182. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4281991/


[19] Brosseau, L., Welch, V., Wells, G. A., de Bie, R., Gam, A., Harman, K., Morin, M., Shea, B., & Tugwell, P. (2005). Low level laser therapy (Classes I, II and III) for treating rheumatoid arthritis. Cochrane Database of Systematic Reviews. https://doi.org/10.1002/14651858.cd002049.pub2


[20] Freitas, A. C. C., Campos, L., Brandão, T. B., Cristófaro, M., Eduardo, F. de P., Luiz, A. C., Marques, M. M., Eduardo, C. de P., & Simões, A. (2014). Chemotherapy-Induced Oral Mucositis: Effect of LED and Laser Phototherapy Treatment Protocols. Photomedicine and Laser Surgery, 32(2), 81–87. https://doi.org/10.1089/pho.2013.3576


[21] Zhou, L., Tong, L., Li, Y., Williams, B. T., & Qiu, K. (2023). Photobiomodulation therapy retarded axial length growth in children with myopia: evidence from a 12-month randomized controlled trial evidence. Scientific Reports, 13(1), 3321. https://doi.org/10.1038/s41598-023-30500-7


[22] Fantaguzzi, F., Tombolini, B., Servillo, A., Ilaria Zucchiatti, Riccardo Sacconi, Bandello, F., & Querques, G. (2023). Shedding Light on Photobiomodulation Therapy for Age-Related Macular Degeneration: A Narrative Review. Ophthalmology and Therapy, 12(6), 2903–2915. https://doi.org/10.1007/s40123-023-00812-y


[23] Iosifescu, D. V., Norton, R. J., Ümit Tural, Mischoulon, D., Collins, K. A., McDonald, E., Luis De Taboada, Foster, S. L., Cusin, C., Yeung, A., Clain, A., Schoenfeld, D., Hamblin, M. R., & Cassano, P. (2022). Very Low-Level Transcranial Photobiomodulation for Major Depressive Disorder. The Journal of Clinical Psychiatry, 83(5). https://doi.org/10.4088/jcp.21m14226


[24] Ji, Q., Yan, S., Ding, J., Zeng, X., Liu, Z., Zhou, T., Wu, Z., Wei, W., Li, H., Liu, S., & Ai, S. (2024). Photobiomodulation improves depression symptoms: a systematic review and meta-analysis of randomized controlled trials. Frontiers in Psychiatry, 14. https://doi.org/10.3389/fpsyt.2023.1267415


[25] Gao, Y., An, R., Huang, X., Liu, W., Yang, C., & Wan, Q. (2023). Effectiveness of photobiomodulation for people with age-related cognitive impairment: a systematic review and meta-analysis. Lasers in Medical Science, 38(1). https://doi.org/10.1007/s10103-023-03899-8


[26] Syed, S. B., Ahmet, I., Chakir, K., Morrell, C. H., Arany, P. R., & Lakatta, E. G. (2023). Photobiomodulation therapy mitigates cardiovascular aging and improves survival. Lasers in Surgery and Medicine, 55(3), 278–293. https://doi.org/10.1002/lsm.23644

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