Introduction
Red light therapy has become increasingly popular as a non-invasive approach used in wellness, recovery, skincare, and other applications. You may also see it described as photobiomodulation (PBM) or low-level light therapy (LLLT).
But what exactly is red light therapy, and how does light interact with the body?
This guide explains the basics of red and near-infrared light, how photobiomodulation is thought to work, and what to consider before using a red light therapy device.
What Is Red Light Therapy?
Red light therapy is a form of photobiomodulation that exposes the body to specific wavelengths of red or near-infrared light at relatively low energy levels.
Unlike ultraviolet (UV) light, red and near-infrared light are different portions of the electromagnetic spectrum and are used in photobiomodulation without the goal of heating or damaging tissue.
Scientific literature commonly describes photobiomodulation as using wavelengths within the red and near-infrared ranges. Different wavelengths, devices, treatment parameters, and applications can produce different biological responses.
How Does Red Light Therapy Work?
Researchers continue to investigate the exact mechanisms behind photobiomodulation.
One leading explanation involves the mitochondria—the structures inside cells involved in producing cellular energy. Research suggests that red and near-infrared photons may interact with light-sensitive cellular components, including cytochrome c oxidase, an enzyme involved in the mitochondrial respiratory chain.
These interactions may influence cellular energy production and signaling processes involving ATP, reactive oxygen species, nitric oxide, and calcium.
However, photobiomodulation is highly dependent on treatment parameters. More light is not necessarily better. Wavelength, irradiance, treatment time, total energy delivered, distance from the light source, and the tissue being targeted can all influence the response.
We explore these mechanisms in more detail in our guide: How Red Light Therapy Works.
Red Light vs. Near-Infrared Light
Red and near-infrared light are related but are not identical.
Red light is visible to the human eye and generally occupies the longer-wavelength portion of the visible spectrum.
Near-infrared light (NIR) has a longer wavelength and sits just beyond visible red light, so it is generally invisible to the human eye.
Many consumer photobiomodulation devices combine red and near-infrared wavelengths. For example, some devices use wavelengths around 660 nm and 850 nm.
The appropriate wavelength should not be considered in isolation. Device output, treatment duration, distance, dose, and intended use are also important.
What Is Red Light Therapy Commonly Used For?
Photobiomodulation has been studied across a wide range of applications, including areas related to skin, recovery, discomfort, inflammation, wound healing, and other clinical or wellness uses.
However, the strength of evidence varies considerably depending on the application, device, wavelength, dose, and study design.
For consumers, this distinction matters: promising research in one setting does not automatically mean that every red light device will produce the same result.
When evaluating a red light therapy device, consider its intended use and follow the manufacturer's instructions rather than assuming that higher power or longer sessions will necessarily produce better outcomes.
What Does the Research Say?
Photobiomodulation has been investigated for decades, and researchers have identified several plausible biological mechanisms associated with red and near-infrared light.
At the same time, clinical research remains heterogeneous. Studies may use different wavelengths, light sources, treatment schedules, power levels, and outcome measures, which can make direct comparisons difficult.
For that reason, red light therapy should not be presented as a universal treatment or cure.
A responsible approach is to evaluate evidence for the specific application and treatment protocol rather than treating “red light therapy” as a single standardized intervention.
Is Red Light Therapy Safe?
Photobiomodulation is generally described in the scientific literature as well tolerated when appropriately administered, but safety depends on the device, treatment parameters, individual circumstances, and intended use.
Light-based procedures can also present eye-safety concerns, and certain medical conditions or medications may require additional precautions. FDA consumer information, for example, identifies photosensitivity and photosensitizing medications among situations requiring particular consideration for some light-based procedures.
Always follow the instructions and safety guidance supplied with your specific device.
If you have a medical condition, take photosensitizing medication, are pregnant, have concerns about your eyes or skin, or are unsure whether a device is appropriate for you, consult a qualified healthcare professional before use.
For more guidance, see Safety & Best Practices.
Choosing a Red Light Therapy Device
When comparing devices, look beyond the number of LEDs.
Useful factors to consider include:
- Wavelengths
- Irradiance and treatment distance
- Recommended session duration
- Treatment area and fit
- Device design and comfort
- Safety instructions
- Intended use
- Manufacturer information and product documentation
For wearable devices in particular, fit and positioning can also affect how consistently the light reaches the intended area.
How to Get Started
If you are new to red light therapy, begin by understanding what your device is designed to do.
Read its instructions, identify the recommended treatment duration and positioning, and avoid assuming that longer or more frequent sessions are automatically better.
DEPOWIN develops wearable red light devices designed around convenient, targeted use for different areas of the body. When choosing a device, consider where you intend to use it and which design best fits your routine.
Frequently Asked Questions
Is red light therapy the same as infrared therapy?
Not exactly. Red light is visible, while near-infrared light uses longer wavelengths beyond the visible red portion of the spectrum. Some photobiomodulation devices combine both.
What do 660 nm and 850 nm mean?
The numbers describe the wavelength of the light in nanometers (nm). Approximately 660 nm is in the red portion of the spectrum, while 850 nm is near-infrared.
Can you see near-infrared light?
Near-infrared light around 850 nm is generally outside the range visible to the human eye. Therefore, an NIR LED can be operating even though it does not appear as bright as a visible red LED.
Is more red light always better?
No. Photobiomodulation responses depend on multiple treatment parameters, including wavelength, irradiance, exposure time, and total dose. Increasing exposure does not automatically improve results.
How often should I use red light therapy?
There is no single schedule that applies to every device or application. Follow the instructions supplied with your specific product.
Does red light therapy replace medical treatment?
No. Consumer red light therapy information should not be used as a substitute for professional medical diagnosis or treatment.
Learn More
Red light therapy is a broad field, and understanding the fundamentals makes it easier to evaluate devices and claims responsibly.
Continue learning:
How Red Light Therapy Works
Learn more about wavelengths, photobiomodulation, mitochondria, and treatment parameters.
Safety & Best Practices
Learn how to approach red light therapy responsibly and what precautions to consider.
References & Further Reading
1. Avci P, Gupta A, Sadasivam M, et al.
Low-Level Laser (Light) Therapy (LLLT) in Skin: Stimulating, Healing, Restoring.
Seminars in Cutaneous Medicine and Surgery. 2013.
2. de Freitas LF, Hamblin MR.
Proposed Mechanisms of Photobiomodulation or Low-Level Light Therapy.
IEEE Journal of Selected Topics in Quantum Electronics. 2016.
3. Hamblin MR.
Mechanisms and Mitochondrial Redox Signaling in Photobiomodulation.
Photochemistry and Photobiology. 2018.
4. Maghfour J, Ozog DM, Mineroff J, et al.
Photobiomodulation CME Part I: Overview and Mechanism of Action.
Journal of the American Academy of Dermatology. 2024.