The Fundamentals
Red Light Therapy Is a Form of Photobiomodulation
In scientific literature, red light therapy is commonly discussed under the broader term photobiomodulation, or PBM. Photobiomodulation uses non-ionizing light—usually in the red and near-infrared portions of the spectrum—to trigger biological responses in cells and tissue. Unlike ultraviolet light, these wavelengths are not used to tan the skin and do not work by deliberately damaging tissue.
PBM has been studied for decades using both lasers and light-emitting diodes (LEDs). Researchers have investigated wavelengths roughly within the 600 to 1100 nanometer range, with much of the clinical and laboratory research concentrated around red wavelengths near 630-670 nm and near-infrared wavelengths near 780-850 nm.
The effect is not determined by wavelength alone. Irradiance, total energy delivered, treatment time, distance from the light source, pulse pattern, treatment frequency and the tissue being targeted all influence the biological response.
Cellular Science
How Red & Near-Infrared Light Interact With Cells
The science is still developing, but several biological pathways are repeatedly discussed in photobiomodulation research.
01
Light Enters Tissue
Photons from red and near-infrared light can pass through the skin and be scattered, reflected or absorbed by molecules in tissue. Wavelength strongly affects how far light can travel. Red light is generally used for more superficial targets, while near-infrared wavelengths tend to penetrate farther before their intensity falls.
02
Mitochondria Respond to Light
One of the leading proposed mechanisms involves cytochrome c oxidase, an enzyme in the mitochondrial respiratory chain. Absorption of light may influence mitochondrial activity and temporarily change ATP production, nitric-oxide signaling and reactive oxygen species. These changes can act as cellular signals rather than simply providing energy in the everyday sense.
03
Cell Signaling Changes
Downstream effects may involve calcium signaling, gene expression, inflammatory pathways and other cell-response systems. Researchers are also studying light-sensitive membrane proteins and extracellular signaling mechanisms. No single pathway explains every reported PBM effect, and the dominant mechanism may vary by wavelength, tissue and dose.
Wavelength
Why Wavelength Matters
Wavelength determines both the color of the light and how strongly different molecules in the body absorb it. In PBM research, visible red wavelengths around 600-700 nm are commonly associated with more superficial tissue, while near-infrared wavelengths around 780-950 nm are often selected when the treatment target lies deeper.
This does not mean that a longer wavelength automatically produces a better result. Tissue composition, skin pigmentation, blood flow, water content, treatment geometry and other factors all affect how much light actually reaches a biological target.
Commonly studied for skin and other relatively superficial targets.
Often selected when greater tissue penetration is desired.
Treatment Parameters
Power Is Only One Part of the Dose
A high-output device can deliver photons quickly, but power alone does not determine whether a photobiomodulation treatment will be effective. Research repeatedly shows that PBM depends on a combination of parameters.
Wavelength
Determines which tissue chromophores absorb the light and influences penetration.
Irradiance
Power delivered over an area, commonly expressed as milliwatts per square centimeter (mW/cm²).
Fluence
Total energy delivered over an area, commonly expressed as joules per square centimeter (J/cm²).
Time & Distance
Treatment duration and the distance between the light source and the body can substantially change the dose reaching tissue.
Pulse & Frequency
Continuous versus pulsed delivery and the spacing between sessions can affect outcomes.
Target Tissue
Skin, muscle, nerve and other tissues differ in optical properties and biological response.
A Key Concept
More Light Is Not Automatically Better
Photobiomodulation is frequently described as having a biphasic dose response. In simple terms, a dose that is too low may not produce a meaningful response, while a dose that is too high may be less effective or produce a different response than intended.
That is one reason scientific papers emphasize reporting wavelength, irradiance, fluence, treatment duration and other parameters rather than describing a treatment only as “red light.”
This also explains why two devices can look similar while delivering very different treatments. LED count, wavelength distribution, spacing, optical design, distance from the body and measured output all influence the amount and pattern of light reaching tissue.
Our Whole-Body System
TheraLight 360i at Choice Vision Care & Wellness
Choice Vision Care & Wellness uses the TheraLight 360i for whole-body red and near-infrared light sessions. The specifications presented on our existing therapy page describe the system as using 48,000 LEDs, delivering irradiance up to 165 mW/cm², and offering wavelengths that extend to 940 nm. The system also includes integrated Pulsed Electromagnetic Field (PEMF) technology.
Those specifications describe the device; they do not by themselves predict an individual treatment result. In photobiomodulation, the biological response depends on how the device parameters are combined with treatment time, wavelength selection, target tissue and session protocol.
PEMF is a separate modality from photobiomodulation. Although the TheraLight system can deliver both during a session, the scientific evidence and proposed mechanisms for PEMF should be evaluated separately from the evidence for red and near-infrared light.
Research & Expectations
What the Research Can—and Cannot—Tell Us
Photobiomodulation has a substantial research history, but the strength of evidence is not the same for every condition or treatment goal. Studies have investigated PBM in areas that include wound healing, pain and inflammation, oral supportive care, dermatology, musculoskeletal conditions, neurologic research and ophthalmology. Results can differ because studies use different wavelengths, doses, devices, treatment schedules and patient populations.
For that reason, red light therapy should not be presented as a universal cure or as a treatment that works simply because a device produces a high irradiance. A scientifically responsible approach considers the intended target, the treatment parameters and the quality of evidence for that specific use.
Safety and Practical Use
Red and near-infrared PBM is non-ionizing and does not use ultraviolet radiation. Nevertheless, bright therapeutic light and high-output devices should be used according to device instructions and an appropriate treatment protocol. Eye protection and eye-exposure guidance should be followed exactly as specified for the device. Tell your provider about medications or medical conditions that could affect light sensitivity or treatment planning.
Scientific Reading
Selected Photobiomodulation References
These reviews explain the proposed mechanisms, wavelength ranges and dosing variables discussed on this page.
- Review of light parameters and photobiomodulation efficacy
- Proposed mechanisms of photobiomodulation or low-level light therapy
- Photobiomodulation use in ophthalmology: an overview of translational research
- Photobiomodulation: lasers versus light-emitting diodes
This page is educational and is not a substitute for diagnosis or individualized medical advice.
Wellington, Florida
Experience Red Light Therapy at Choice Vision Care & Wellness
Learn more about our whole-body TheraLight 360i sessions or reserve an appointment online.
8475 Lake Worth Rd. Ste 200Wellington, FL 33467