Why 940 nm Matters: The Science Behind This Near-Infrared Wavelength

940 nm is one of the wavelengths I am most excited about in my red light product line.

When I started researching red light therapy, I wanted to understand more than just which wavelengths were in every product on the market. I wanted to know what each wavelength actually brought to the system: how it moved through tissue, how much was absorbed or scattered, and what kinds of biological responses had been reported at that specific wavelength.

940 nm kept giving me reasons to pay attention.

1. 940 nm has impressive tissue-transmission research behind it

One of the studies that really caught my attention tested 750 and 940 nm near-infrared light through fresh, unfixed human cadaver heads. Researchers were able to detect 940 nm after transmission through the full 4 cm tissue path used in the experiment. In the whole-head measurements, 940 nm also showed greater transmission than 750 nm. [1]

That is a big deal from an engineering standpoint because the light has to get through whatever stands between the source and the target. Skin, soft tissue, pigmentation, hair, bone, geometry and treatment distance all influence what ultimately reaches deeper tissues.

The study used a laser light source on human cadaver tissue, so it is not a direct measurement of an equine light device, but it gives us verifiable evidence that 940 nm wavelength can travel through a substantial thickness of biological tissue.

2. 940 nm has shown strong responses in ligament-derived stem cells

In a direct comparison of 810 and 940 nm photobiomodulation (red light therapy) on periodontal-ligament-derived stem cells, the 940 nm group at 2.5 J/cm² showed significantly increased cell viability and proliferation under that protocol. The 810 nm treatment at the same energy density did not produce the same response. [2]

Another study specifically examined 940 nm photobiomodulation in inflamed periodontal ligament stem cells and evaluated effects on proliferation and osteogenic differentiation. [3]

These are human periodontal ligament cells, not equine suspensory ligaments, but the research is still important because it demonstrates that 940 nm can produce meaningful wavelength-specific cellular responses in connective tissue cells (tendons and ligaments).

3. The cartilage research is especially exciting

A 2025 LED study compared photobiomodulation at 625, 810, 940 and 1050 nm. In the cell experiments, 940 nm at 52 J/cm² produced the strongest suppression of several cartilage-degradation markers and increased markers associated with cartilage matrix. In the animal osteoarthritis model, that same 940 nm protocol reduced cartilage degradation and improved weight-bearing asymmetry compared with untreated controls. [4]

A separate 2025 study using human chondrocytes found that 940 nm LED treatment at specific irradiance settings promoted collagen type II, aggrecan and glycosaminoglycan deposition while preserving the normal chondrocyte phenotype. [5]

For me, this is where 940 nm becomes magical for products that can be positioned over joints and other connective tissue rich areas!

4. Why 940 nm matters in a multi-wavelength system

Photobiomodulation is wavelength-dependent. Different wavelengths interact differently with tissue and can produce different cellular responses depending on the dose, target and treatment conditions.

That is why I built my products around 660 + 850 + 940 nm. Each wavelength contributes something different to the system, and 940 nm gives me a near-infrared wavelength with compelling penetration, connective-tissue and cartilage research behind it.

I am not interested in adding features just because they sound good on a spec sheet. And let’s be real- I am a nerd not a marketing expert so if I am going to build something different into a product, I want a scientific reason for doing it.

940nm earned its place in my redlight therapy product line.

Keep reading the science

For the full explanation of why I combined 660 + 850 + 940 nm in my equine products, read Red Light Therapy Q&A: Why I Engineered My Equine Products Differently.

Want to see the products built around that wavelength strategy? Explore VanHorn Equine Red Light Therapy.

Educational information only. The studies discussed above include human cells, human cadaver tissue and animal models. They do not establish that a consumer equine LED device diagnoses, treats or cures disease. Photobiomodulation outcomes depend on wavelength, irradiance, fluence, treatment time, tissue type and device design.