Light comes in lots of different colours. Some colours, like red, you can see with your eyes. Other colours are invisible, but they are still real, a bit like the warm feeling on your skin when the sun is out. Different colours can sneak into your body at different depths. Some only touch the very top of your skin. Others go a bit deeper, all the way down to your muscles.
For faces, the red light you can see is the best one. It lands exactly where your skin builds the stretchy stuff that keeps it smooth. The invisible warm light is better for sore muscles and achy knees, because it sneaks deeper. A good face mask shines both colours at once, so it can help in two places at the same time.
660nm for skin, 850nm for depth.
660nm sits in the visible red range and penetrates one to two millimetres into the dermis where fibroblasts produce collagen, which is why it dominates the facial-skin literature. 850nm is near-infrared, reaches several centimetres into muscle and joint tissue, and dominates the deep-tissue and pain literature. Each wavelength meets its target tissue at the appropriate depth, so the right answer depends on the goal rather than which wavelength is technically deeper. Combined protocols are mechanistically reasonable, but the head-to-head data on which wavelength contributes more is genuinely thin.
How they differ physically
Both wavelengths trigger the same general photobiomodulation pathway. They're absorbed by mitochondrial cytochrome c oxidase, lift ATP production, and signal downstream tissue repair and synthesis effects. The difference between them isn't mechanism. It's depth.
660nm sits in the visible red range. It penetrates well into the upper dermis of skin, around 1 to 2 millimetres, which is exactly where fibroblasts produce collagen and elastin. The wavelength meets its target tissue at the depth fibroblasts actually live. This is why 660nm dominates the skin-rejuvenation literature.
850nm is just past the visible spectrum, in the near-infrared range. It penetrates deeper than visible red, reaching muscle tissue, joint capsules, and connective tissue several centimetres below the surface. The trade-off is reduced interaction with the surface dermis, where most facial skin work happens. 850nm is dominant in the muscle, joint, and pain literature for the same reason 660nm is dominant in the skin literature: each wavelength meets its target tissue at the appropriate depth.
When 660nm is the right choice
If your goal is anything to do with facial skin (fine lines, wrinkles, collagen support, skin tone, periocular skin, acne-prone skin), the 630 to 660nm range is the wavelength band with the strongest, most replicated clinical evidence.
Lee et al. 2007: 36% wrinkle reduction in a split-face RCT
Lee and colleagues (PMID 17566756, Journal of Photochemistry and Photobiology B) ran a prospective, randomized, placebo-controlled, double-blinded, split-face study in 76 patients. The split-face design controls for genetics, sun history, and lifestyle within the same person. Each patient received the active treatment on one side of the face and a placebo on the other.
Participants received combined 633nm red and 830nm near-infrared LED (a typical skin-rejuvenation pairing). Outcomes were measured by objective elasticity instruments and histology of skin biopsies. Wrinkle reduction reached up to 36% on the actively treated side. Skin elasticity rose by up to 19%. Histology confirmed increased collagen and elastic fibre density. The trial is one of the cornerstones of the facial-skin LED literature: it documents both the visible photographic outcome and the underlying tissue change in the same study, with one of the most rigorous designs available.
Supporting skin evidence
Three additional studies extend the skin pattern. Barolet et al. 2009 (PMID 19587693) showed pulsed 660nm LED increased type-1 procollagen by approximately 31% and decreased MMP-1 by 18% in human dermal fibroblasts. Mota et al. 2023 (PMID 36780572) reported a 31.6% reduction in periocular wrinkle volume after 10 sessions of 660nm LED in 137 women. Li et al. 2021 (PMID 33594706) mapped the gene-expression response to combined red and near-infrared LED in human dermal fibroblasts, showing clear upregulation of collagen and elastin genes. The Avci et al. 2013 review (PMID 24049929) catalogues the broader mechanism, summarising that red and near-infrared wavelengths absorbed by mitochondrial chromophores stimulate ATP production and fibroblast activity for measurable wrinkle, collagen, and photoaging effects.
When 850nm makes more sense
If your goal is deeper-tissue (joint pain, muscle recovery, full-body protocols), 850nm or combined 660 plus 850nm devices have a larger evidence base. The deeper penetration is what you're paying for.
Hegedus et al. 2009: 830nm in knee osteoarthritis
Hegedus and colleagues (PMID 19530911, Photomedicine and Laser Surgery) ran a double-blind randomized placebo-controlled trial of 830nm low-level laser therapy in patients with knee osteoarthritis. The trial design is among the most rigorous available, with active and placebo groups receiving identical-looking treatment to control for placebo and observer effects.
Active 830nm LLLT produced significant improvements in pain reduction, joint flexibility, and pressure sensitivity compared to placebo. The wavelength reaches the joint capsule and surrounding connective tissue at the depth needed for the inflammatory and tissue-recovery effects to register. This trial sits at the centre of the deep-tissue LED literature for joint applications, and it's one of the cleaner pieces of evidence for why 850nm dominates this clinical category.
Supporting deep-tissue evidence
Three additional trials extend the deep-tissue pattern. Navarro-Ledesma et al. 2022 (PMID 36369323) ran a triple-blinded RCT of whole-body 660 plus 850nm photobiomodulation in fibromyalgia patients and reported significant pain reduction and improved quality of life after four weeks. Chang et al. 2020 (PMID 32769919) ran a double-blind RCT of combined 630 plus 850nm LED in non-specific low back pain in working nurses, reporting significantly reduced VAS pain scores and improved lumbar range of motion versus sham. Albarracin et al. 2016 (PMID 26949625) reviewed the broader photobiomodulation literature in retinal applications, where 630 to 850nm wavelengths show efficacy across multiple retinal disease models. These applications sit outside facial skincare, but they demonstrate why 850nm and combined protocols are well-studied for deeper structures.
Where the evidence is honestly thin
Most cosmetic LED trials use combined 630 plus 850nm or 633 plus 830nm protocols. Few have run head-to-head designs that test each wavelength alone in the same trial to see what each contributes. The combination is empirically effective. Whether you could get the same effect from red alone, from NIR alone, or from a different ratio is a question the field has not fully answered.
Mota et al. 2023's split-face design comparing 660nm to 590nm amber is the closest available head-to-head wavelength comparison in skin work, and the two produced close to equivalent results (31.6% versus 29.9% periocular wrinkle volume reduction). What that suggests is that wavelength specificity within the visible-red region may matter less than commonly assumed, but the comparison didn't include 830 or 850nm so the deeper-penetrating wavelength wasn't in the test.
The honest read is that combined protocols are well-validated empirically, single-wavelength specificity within a category (red versus amber, NIR versus far-NIR) is less rigorously established, and head-to-head red-vs-NIR for skin-specific outcomes hasn't been cleanly run. We say this because it matters when you're evaluating marketing claims that present specific wavelengths as proven optimal.
There's a related point about total dose versus single-wavelength specificity. The dose delivered (irradiance multiplied by time, in joules per square centimetre) is often more determinative of outcome than the exact wavelength within the appropriate category. A 633nm protocol at the right dose tends to outperform a 660nm protocol at the wrong dose, and vice versa. This is part of why our dosage calculator exists: getting the dose right is a bigger lever than chasing the perfect wavelength to two decimal places.
The practical decision
Pick 660nm (or 630 to 660nm) if your goal is
- Wrinkles, fine lines, periocular skin
- Collagen support, skin tone, texture
- Acne-prone skin (often combined with blue)
- Face-only at-home sessions
Pick 850nm (or 660 plus 850nm) if your goal is
- Joint pain, muscle recovery
- Deep-tissue protocols, full-body use
- Pain conditions like back pain, fibromyalgia
- Panel devices with broader coverage
Combined protocols (red plus NIR) layer both depths in a single session and are well-supported across both skin and deep-tissue applications. For most users with multi-faceted goals (face plus occasional joint or muscle support), a combined-wavelength device is the practical fit. For users with a single dominant goal, a specialised device may deliver more usable irradiance at the target wavelength.
How our mask fits in
Red Light Rejuve is a face-shaped mask that covers both red and near-infrared. It runs 633nm in the red range (the wavelength range at the centre of the skin-rejuvenation evidence) plus dual near-infrared at 850nm and 1072nm, paired with red in modes like Anti-Aging and Bedtime Skincare. Three hundred and sixty medical-grade LEDs cover the full mask surface, with 415nm blue and 590nm yellow available across the six preset modes. For facial skincare with optional NIR depth, this is the intended form factor. For dedicated whole-body deep-tissue protocols (large joints, full-spine sessions), a body-panel device with broader area coverage is the better tool, and we'll say so. Sessions run 10 minutes. Sixty-day money-back guarantee, two-year warranty, free express shipping AU-wide.
Skin-focused studies (660nm range)
Lee SY, et al. · Journal of Photochemistry and Photobiology B · 2007 · PMID 17566756
“A prospective, randomized, placebo-controlled, double-blinded, and split-face clinical study on LED phototherapy for skin rejuvenation”
Objectively measured data showed significant reductions in wrinkles (up to 36%) and increases in skin elasticity (up to 19%); histology confirmed increased collagen and elastic fibers.
View on PubMed →Barolet D, et al. · Journal of Investigative Dermatology · 2009 · PMID 19587693
“Regulation of skin collagen metabolism in vitro using a pulsed 660 nm LED light source: clinical correlation with a single-blinded study”
Pulsed 660nm LED increased type-1 procollagen by ~31% and decreased MMP-1 by ~18%; clinically, more than 90% of subjects showed reduced rhytid depth after 12 treatments.
View on PubMed →Li WH, et al. · International Journal of Cosmetic Science · 2021 · PMID 33594706
“Low-level red plus near infrared lights combination induces expressions of collagen and elastin in human skin in vitro”
Combined red (640nm) and NIR (830nm) LED significantly upregulated COL1A1, COL3A1, ELN, and LOXL1 gene expression and increased procollagen type I and elastin protein synthesis in human dermal fibroblasts.
View on PubMed →Mota LR, et al. · Photobiomodulation, Photomedicine, and Laser Surgery · 2023 · PMID 36780572
“Photobiomodulation Reduces Periocular Wrinkle Volume by 30%: A Randomized Controlled Trial”
In 137 women aged 40-65, 10 sessions of red (660nm) LED reduced periocular wrinkle volume by 31.6% and amber (590nm) LED by 29.9% compared to controls.
View on PubMed →Avci P, et al. · Seminars in Cutaneous Medicine and Surgery · 2013 · PMID 24049929
“Low-level laser (light) therapy (LLLT) in skin: stimulating, healing, restoring”
Red and near-infrared wavelengths absorbed by mitochondrial chromophores stimulate ATP production and fibroblast activity, with clinical evidence for wrinkle reduction, collagen induction, and reversal of photoaged skin.
View on PubMed →
Deep-tissue studies (850nm and combined)
Hegedus B, et al. · Photomedicine and Laser Surgery · 2009 · PMID 19530911
“The Effect of Low-Level Laser in Knee Osteoarthritis: A Double-Blind, Randomized, Placebo-Controlled Trial”
Active LLLT at 830nm demonstrated significant improvements in pain reduction, joint flexibility, and pressure sensitivity compared to placebo.
View on PubMed →Navarro-Ledesma S, et al. · Pain and Therapy · 2022 · PMID 36369323
“Short-Term Effects of Whole-Body Photobiomodulation on Pain, Quality of Life and Psychological Factors in Fibromyalgia”
Whole-body PBM using 660nm and 850nm LEDs resulted in significant pain reduction and improved quality of life in fibromyalgia patients after 4 weeks.
View on PubMed →Chang WD, et al. · Medicine (Baltimore) · 2020 · PMID 32769919
“Light-emitting diode photobiomodulation therapy for non-specific low back pain in working nurses”
LED at 630nm and 850nm delivered 3 times weekly significantly reduced VAS pain scores and improved lumbar range of motion versus sham.
View on PubMed →Albarracin R, Eells J, Valter K · Photomedicine and Laser Surgery · 2016 · PMID 26949625
“Photobiomodulation for the treatment of retinal diseases: a review”
Red and near-infrared light (630-850nm) protects photoreceptors from degeneration, improves visual function in AMD and diabetic retinopathy, and shows efficacy across multiple retinal disease models.
View on PubMed →
See our full research database for the complete catalogue of peer-reviewed studies.
FAQ
Is 850nm better than 660nm?
Neither is universally better. They are studied for different things. 660nm is the wavelength range with the strongest evidence base for facial skin, collagen synthesis, and surface dermal effects. 850nm penetrates deeper into muscle and joint tissue and has the larger evidence base for those use cases. The right answer depends on what you are trying to do, not which wavelength is technically deeper or longer.
Does the Red Light Rejuve mask include 850nm?
Yes. The mask covers both 850 and 1072 nanometre near-infrared bands, paired with 633 nanometre red in modes like Anti-Aging and Bedtime Skincare. The product is built around the wavelength most-cited for facial skin (633nm), with near-infrared layered alongside it in modes that combine red and NIR. For dedicated whole-body deep-tissue use, a body-panel device with broader area coverage is typically a better tool, and we'll say so.
Can one device do both skin and deep-tissue work well?
Devices that emit both 660nm and 850nm exist, and several published trials use combination protocols. Whether a single device does both well depends on irradiance and area coverage at each wavelength, not just whether both LEDs are present in the spec sheet. Specialised devices for skin or for deep tissue tend to deliver more usable irradiance at their target wavelength than general-purpose devices that try to do everything.
Which wavelength is safer near the eyes?
Both red and near-infrared wavelengths are non-ionising and have strong safety profiles in published clinical literature. Eye protection or eyes-closed use is recommended for any visible-red or near-infrared facial device, regardless of wavelength. Users with hereditary eye conditions, recent eye surgery, or who take photosensitising medications should consult an ophthalmologist before starting LED therapy.
What about combined 660 plus 850nm protocols?
Combined protocols are well-studied for body and full-system use cases. Navarro-Ledesma 2022 (PMID 36369323) tested whole-body 660 plus 850nm PBM in fibromyalgia. Chang 2020 (PMID 32769919) tested combined 630 plus 850nm in non-specific low back pain. For face-specific outcomes, the strongest replicated evidence still sits with red wavelengths in the 630 to 660nm range, sometimes paired with 830nm. The combination is mechanistically reasonable but the head-to-head data on whether each wavelength contributes equally is genuinely thin.
Related guides
- Red light therapy for collagen
Mechanism, gene expression, and the 630 to 660nm story.
- Red light therapy for wrinkles
Effect sizes from the strongest randomized trials.
- Red light therapy for crow's feet
The most-photographed periocular outcome, in detail.
- Dosage calculator
Work out irradiance and time for your target dose.
Red plus near-infrared, in one face-shaped mask.
Red Light Rejuve covers 633nm red and dual near-infrared at 850nm and 1072nm, alongside 415nm blue and 590nm yellow, across six preset modes. The red band sits at the centre of the skin-rejuvenation evidence, and NIR is paired with it in the Anti-Aging and Bedtime modes for users who want to layer in deeper-penetrating wavelengths. 360 medical-grade LEDs, 60-day money-back guarantee.