Red Light & Infrared: What Does Research Say About Light Wavelengths?
Magdalena Bürk
Red light and infrared are often advertised with big promises. This article, however, examines what science actually says about the individual wavelengths.
From blue light to red light to near-infrared: Each wavelength has different effects and varying levels of research. These differences are categorized here, wavelength by wavelength.
Important to know: The article describes the general state of research on light wavelengths. It does not make any claims about the effectiveness of a specific product and does not replace medical advice.
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The principle behind it: Why light at all?
Light is electromagnetic radiation. The human eye perceives only a narrow portion of it—the visible light from about 380 to 700 nanometers (nm). Directly adjacent is the near-infrared, invisible to the eye but just as real to the skin.
Why is research particularly interested in the range between 480 and 1060 nm?
Because this is where an optical window lies: In this spectrum, absorption by water, hemoglobin, and melanin in the skin is comparatively low, allowing light to penetrate deeper into the tissue than in neighboring wavelength ranges [1]. This precisely explains why photobiomodulation research has historically focused on this window—not because other wavelengths are ineffective, but because this is where the best-studied interaction with cell biology occurs.
Overview of the Wavelengths
BLUE & GREEN LIGHT
480nm & 525 nm
RED LIGHT
630 nm & 660 nm
NEAR-INFRARED LIGHT
810nm, 830nm, 850nm, 940nm & 1060nm
Blue and green light (480nm & 525 nm): superficial but versatile
Short-wavelength visible light penetrates barely deeper than one to three millimeters into the skin, thus acting primarily on the surface [2].
A well-documented effect of blue light in the range of 400–470 nm is its antimicrobial action. A laboratory study published in 2023 showed that blue light stimulates endogenous porphyrins in bacteria like Cutibacterium acnes, leading to the production of reactive oxygen species that can kill the bacteria [3].
At the same time, chronobiology research shows: Blue light is the strongest known regulator of the internal clock. It is processed through special receptors in the retina and reliably suppresses melatonin secretion [4]. This is a relevant factor for evening use. Green light (around 525 nm) is a newer but growing field of research. A systematic review from 2025 describes effects on bone-related cells via opsins and ion channels [5].
Red Light (630nm & 660nm): the classic, most well-documented range
Red light is at the lower end of the red absorption window of cytochrome c oxidase and penetrates two to five millimeters deep into the dermis [2]. It is one of the most extensively and widely studied wavelengths in all of PBM research. A controlled human study from 2014 specifically examined the effects of red and near-infrared light on skin parameters. Measurements included intradermal collagen density via ultrasound, as well as visible wrinkle depth and skin roughness. The result: a statistically significant increase in collagen density compared to untreated controls [6]. It is one of the most robust human studies available on this specific effect. Red light also regularly appears in muscle regeneration: A study on elite female basketball players from 2012 combined red light exposure with measurements of sleep quality, serum melatonin, and endurance performance. The result: significantly higher melatonin levels and better sleep quality in the red light group compared to placebo [7]. A recent study from 2025 confirmed in a direct comparison with blue light that melatonin levels recover significantly faster under red light than under blue light [8].
Near-infrared (810nm, 830nm & 850nm): the physical optimum
According to current research, the so-called optimum for penetration depth and coupling to cytochrome c oxidase lies between 810 and 850 nm [1, 2]. Light in this range can penetrate deeper tissue layers—near-surface muscles and joint areas—significantly deeper than visible light.
This range is by far the most extensively researched, including in the sports context. A placebo-controlled study from 2017 specifically examined which irradiation strength of 810-nm light before training shows the optimal effect on muscle performance and recovery [9]. A systematic review with meta-analysis from 2018 evaluated numerous controlled studies on muscle performance and fatigue, finding favorable effects on repetition count, time to exhaustion, and blood lactate levels in the pooled analysis [10].
Evidence is also relatively strong for delayed onset muscle soreness (DOMS): A recent meta-analysis from 2025, which evaluated 14 controlled studies in the wavelength range of 660–950 nm, found statistically significant effects—a moderate reduction in pain 72 and 96 hours after exertion and a significant improvement in muscle strength after 24 and 48 hours compared to placebo [11]. The authors explicitly emphasize that the overall study situation is still heterogeneous and further high-quality research is needed.
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THE LONGER INFRARED WAVES
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(940nm & 1060 nm): growing, but thinner
From around 950 nm, water begins to play an increasingly significant role as an absorber. This changes the physical behavior compared to the classic 810–850 nm window: The theoretical penetration depth continues to increase, while the coupling to cytochrome c oxidase tends to become weaker [1].
Honesty is key here: For the range around 940 nm, there is growing but thinner evidence compared to 810–850 nm. For 1060 nm, the data is even more limited—a professional review even discusses an alternative mechanism for this range: mitochondrially bound water instead of cytochrome c oxidase as the primary target [12]. This is scientifically interesting, but not nearly as well-supported as the findings for the classic red/near-infrared window.
Conclusion:
Solid Foundation, Honest Limits
Research on photobiomodulation presents a nuanced picture:
- Our wavelengths between 630nm - 850 nm are the most scientifically supported range, with the broadest and longest-established body of studies, particularly regarding collagen formation, muscle regeneration, and cellular energy metabolism.
- 480 nm (Blue) shows a well-documented, specific effect (antimicrobial) and a clearly evidenced role in chronobiology.
- 525 nm (Green) is a young, emerging research field with its own distinct mechanism.
- 940 and 1060 nm are physically in the deepest penetrating range but have comparatively thinner evidence—more research is needed here before reliable conclusions can be drawn.
And the most important common thread throughout the literature: The underlying mechanism of action—particularly the NO photodissociation hypothesis—is considered the most accepted but not conclusively proven explanation [13].
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SOURCES
- de Freitas, L.F. and Hamblin, M.R. (2016) 'Proposed Mechanisms of Photobiomodulation or Low-Level Light Therapy', IEEE Journal of Selected Topics in Quantum Electronics, 22(3), pp. 348–364. doi: 10.1109/JSTQE.2016.2561201.
- Avci, P. et al. (2013) 'Low-Level Laser (Light) Therapy (LLLT) in Skin: Stimulating, Healing, Restoring', Seminars in Cutaneous Medicine and Surgery, 32(1), pp. 41–52. doi: 10.12788/j.sder.0032.
- Cotter, L. et al. (2023) 'Antimicrobial Effects of Blue Light Therapy Against Cutibacterium acnes: Optimal Dosing and Impact of Serial Treatments', JSES International, 8(2), pp. 328–334. doi: 10.1016/j.jseint.2023.11.020.
- Wahl, S. et al. (2019) 'The Inner Clock – Blue Light Sets the Human Rhythm', Journal of Biophotonics, 12, e201900102. doi: 10.1002/jbio.201900102.
- Bao, W., Zhuang, J., Liu, F., Hu, J., Chen, X. and Jiang, Y. (2025) 'Green Light Photobiomodulation: A Systematic Review of New Approaches for Treating Bone Repair', Photobiomodulation, Photomedicine, and Laser Surgery, 43(12), pp. 565–584. doi: 10.1177/25785478251381479.
- Wunsch, A. and 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), pp. 93–100. doi: 10.1089/pho.2013.3616.
- Zhao, J., Tian, Y., Nie, J., Xu, J. and Liu, D. (2012) 'Red Light and the Sleep Quality and Endurance Performance of Chinese Female Basketball Players', Journal of Athletic Training, 47(6), pp. 673–678. doi: 10.4085/1062-6050-47.6.08.
- Sanchez-Cano, A., Luesma-Bartolomé, M.J., Solanas, N. and Orduna-Hospital, E. (2025) 'Comparative Effects of Red and Blue LED Light on Melatonin Levels During Three-Hour Exposure in Healthy Adults', Life, 15(5), 715. doi: 10.3390/life15050715.
- de Oliveira, A.R. et al. (2017) 'Pre-Exercise Infrared Photobiomodulation Therapy (810 nm) in Skeletal Muscle Performance and Postexercise Recovery in Humans: What Is the Optimal Power Output?', Photomedicine and Laser Surgery, 35(11), pp. 595–603. doi: 10.1089/pho.2017.4343.
- Vanin, A.A. et al. (2018) 'Photobiomodulation Therapy for the Improvement of Muscular Performance and Reduction of Muscular Fatigue Associated with Exercise in Healthy People: A Systematic Review and Meta-Analysis', Lasers in Medical Science, 33(1), pp. 181–214. doi: 10.1007/s10103-017-2368-6.
- Tsou, Y.-A., Chang, N.-J. and Chang, W.-D. (2025) 'Effects of Photomodulation Therapy for Delayed Onset Muscle Soreness: A Systematic Review and Meta-Analysis', Journal of Functional Morphology and Kinesiology, 10(3), 277. doi: 10.3390/jfmk10030277.
- Hamblin, M.R. (2018) 'Mechanisms and Mitochondrial Redox Signaling in Photobiomodulation', Photochemistry and Photobiology, 94(2), pp. 199–212. doi: 10.1111/php.12864.
- Quirk, B.J. and Whelan, H.T. (2020) 'What Lies at the Heart of Photobiomodulation: Light, Cytochrome C Oxidase, and Nitric Oxide – Review of the Evidence', Photobiomodulation, Photomedicine, and Laser Surgery, 38(9), pp. 527–530. doi: 10.1089/photob.2020.4905.
