Red Light Therapy vs. Infrared Therapy: A Science-Based Guide to Wavelengths, Benefits, and Applications

Red light therapy and infrared therapy are increasingly used in skincare, fitness recovery, pain management, and general wellness. Yet the two terms are often used interchangeably, creating confusion about how they work, how deeply they penetrate, and which wavelength may be appropriate for different goals.

Both red and near-infrared light can be used as forms of photobiomodulation (PBM), a non-invasive approach in which specific wavelengths of light interact with biological tissues and may influence cellular signaling and energy metabolism.

The key difference is not simply that one is “red” and the other is “infrared.” Wavelength matters. Different wavelengths interact with tissue differently, and this can influence how much light reaches the skin versus deeper tissues.

This guide explains the science behind red and near-infrared light, reviews what current research actually supports, and provides practical guidance for choosing between them.

What Is Photobiomodulation?

Photobiomodulation, commonly abbreviated as PBM, refers to the use of non-ionizing light—typically in the red and near-infrared portions of the electromagnetic spectrum—to produce biological effects.

Unlike ultraviolet (UV) radiation, which can damage cellular DNA and contribute to photoaging and skin cancer, PBM uses specific non-UV wavelengths at controlled doses.

Research suggests that light can interact with cellular photoacceptors, particularly components associated with mitochondrial function. One proposed mechanism involves cytochrome c oxidase, a component of the mitochondrial respiratory chain.

This interaction may influence mitochondrial respiration, ATP production, reactive oxygen species signaling, nitric oxide pathways, and downstream cellular responses.

Importantly, PBM is not simply a matter of “more light equals better results.” Biological responses depend on factors including wavelength, irradiance, energy density, treatment duration, distance from the light source, and the characteristics of the target tissue.

A major review by Hamblin describes PBM as a dose-dependent biological process with effects that can vary depending on treatment parameters. [1]

Red Light vs. Near-Infrared Light: What's the Difference?

The most useful distinction is based on wavelength and tissue penetration.

Red light

Red light occupies the visible portion of the spectrum, generally around 620–750 nm.

Common PBM wavelengths include approximately 630 nm and 660 nm.

Because red light is visible, it produces the familiar red glow associated with many LED therapy devices. It is also strongly relevant to dermatological and cosmetic applications because a greater proportion of its energy is absorbed within relatively superficial tissues.

Near-infrared light

Near-infrared (NIR) light lies just beyond the visible spectrum and is invisible to the human eye.

Common PBM wavelengths include approximately 810, 830, 850 and 880 nm.

Compared with visible red light, NIR wavelengths can generally travel farther into biological tissue because tissue absorption and scattering characteristics change with wavelength.

However, it is important to avoid the oversimplification that “longer wavelength always means deeper penetration.” Tissue optics are more complex: absorption, scattering, irradiance, beam geometry, and the properties of the target tissue all influence how much light reaches a particular depth.

For this reason, wavelength should be considered as one part of the treatment equation, rather than a guarantee of a specific penetration depth.

Red Light Therapy: Primarily Used for Skin and Surface Tissues

Red light therapy is particularly well established in research involving skin and superficial tissues.

One of the most frequently studied wavelengths is 660 nm, which is commonly used in LED-based photobiomodulation devices.

Potential applications of red light therapy include:

Skin appearance and photoaging

Research has investigated red and near-infrared light for improving aspects of skin appearance, including wrinkles, skin texture, elasticity, and collagen-related changes.

For example, a controlled study by Wunsch and Matuschka found that repeated exposure to red and near-infrared light was associated with improvements in skin complexion and measures of skin smoothness and collagen-related appearance. [2]

These findings do not mean that red light can “reverse aging.” Rather, they suggest that appropriately dosed photobiomodulation may support biological processes involved in maintaining healthier-looking skin.

Inflammatory responses

PBM has also been studied for its potential effects on inflammatory signaling. Research suggests that the biological response can involve modulation of oxidative stress, inflammatory mediators, and cellular signaling pathways. [1,3]

Tissue repair

Preclinical and clinical research has explored PBM as a supportive approach for tissue repair and wound-healing processes. The exact response depends on the wavelength and treatment parameters used. [1]

Near-Infrared Therapy: Reaching Deeper Tissues

Near-infrared light, particularly wavelengths in the 800–900 nm range, has attracted considerable interest because more of the emitted light can reach deeper tissues than visible red light under appropriate conditions.

This makes NIR particularly relevant to research involving:

• Muscle recovery
• Exercise performance
• Musculoskeletal discomfort
• Joint-related applications
• Deeper tissue photobiomodulation
• Neurological research

However, “deep penetration” should not be interpreted as meaning that NIR automatically reaches a specific organ, joint, or bone at a therapeutically effective dose.

Actual light delivery depends on the device, treatment distance, irradiance, tissue composition, and exposure time.

NIR and Exercise Recovery

One of the better-studied applications of near-infrared photobiomodulation is exercise recovery.

A systematic review and meta-analysis published in BMJ Open Sport & Exercise Medicine evaluated photobiomodulation therapy for exercise-related muscle recovery and found evidence supporting potential benefits for certain measures of muscle damage and recovery, although results varied across protocols. [4]

Other systematic reviews have similarly examined PBM in sports performance and muscle recovery, highlighting the importance of treatment parameters and wavelength selection. [5]

This is one reason NIR wavelengths are frequently incorporated into recovery-oriented PBM devices.

What About 850 nm?

850 nm is a near-infrared wavelength, rather than a separate category of “deep infrared therapy.”

It is widely used in LED photobiomodulation devices because it is invisible to the human eye and can provide NIR exposure to tissues beneath the skin.

However, it is important to distinguish near-infrared PBM from far-infrared technologies such as infrared saunas.

These technologies are not interchangeable.

Near-infrared PBM

• Typically uses specific wavelengths such as 810–850 nm
• Primarily studied for photobiomodulation
• Uses light energy to influence biological processes
• Does not require strong heating to produce its intended photobiomodulatory effect

Far-infrared heating

• Uses substantially longer wavelengths
• Primarily associated with thermal effects
• Commonly used in infrared saunas and heating applications

In other words, infrared is a broad part of the electromagnetic spectrum, and not every infrared device works through the same mechanism.

Why Many Modern Devices Combine Red and Near-Infrared Light

Instead of choosing exclusively between red and NIR, many PBM devices combine both.

The rationale is straightforward:

Red light → primarily supports superficial tissues and skin-focused applications

Near-infrared light → allows greater light delivery into deeper tissues

Using both wavelengths can therefore provide a broader treatment approach than relying on a single wavelength alone.

For example, a device using 660 nm red light together with 850 nm near-infrared light can provide both visible red and invisible NIR exposure during the same session.

This wavelength combination is used in the WECCT Red Light Therapy Mat with 875 LEDs, 660nm & 850nm Near Infrared Light Therapy Pad.

Designed as a full-body light therapy mat, it combines 660 nm red light with 850 nm near-infrared light, making it suitable for users who want to incorporate both wavelengths into a recovery and wellness routine.

The important point is that the product's wavelength configuration should be viewed in the context of PBM research—not as a guarantee of a specific medical outcome. Treatment results can vary according to dosage, treatment schedule, individual physiology, and other factors.

Red vs. Near-Infrared: Which One Should You Choose?

There is no universally “better” wavelength. The appropriate choice depends on the intended application.

These categories should be viewed as general research applications rather than medical treatment recommendations.

Does a Longer Wavelength Always Mean Better Results?

No.

This is one of the most common misconceptions surrounding light therapy.

It is tempting to assume that a higher wavelength automatically penetrates deeper and therefore produces stronger effects. In reality, PBM is governed by multiple variables.

Wavelength

Determines how photons interact with biological tissue.

Irradiance

Describes the amount of optical power delivered per unit area.

Energy density

Usually expressed as J/cm² and represents the total energy delivered over an area.

Treatment duration

Longer exposure does not necessarily produce better results.

Distance

The distance between the light source and the body can significantly affect the irradiance received.

Tissue characteristics

Skin pigmentation, blood content, water content, tissue thickness, and other optical properties can influence light propagation.

Together, these factors determine the actual dose delivered to the target tissue.

This is why PBM should be considered a dose-dependent intervention rather than simply a wavelength-based treatment. [1]

Is Red Light Therapy the Same as Infrared Therapy?

The most accurate answer is:

They overlap, but they are not the same thing.

Both red and near-infrared light can be used in photobiomodulation, and both may influence cellular processes through related mechanisms.

However, they occupy different regions of the electromagnetic spectrum and interact with biological tissue differently.

Red light is visible and is commonly associated with superficial applications, particularly skin-focused research.

Near-infrared light is invisible and can provide greater light delivery into deeper tissues, making it particularly relevant to research involving muscles and other musculoskeletal tissues.

Rather than thinking of them as competing therapies, it is more accurate to view them as different wavelengths within the broader PBM field.

Can Red and Near-Infrared Light Be Used Together?

Yes.

Combining red and NIR wavelengths is common in modern PBM devices.

The advantage is that different wavelengths can interact with tissue differently, allowing a single treatment session to expose both superficial and deeper tissues.

For example, a 660 nm + 850 nm configuration combines visible red light with near-infrared light.

This type of combination is particularly practical for full-body devices designed around recovery and general wellness.

As with any PBM protocol, however, the expected response depends on the complete treatment parameters—not wavelength alone.

What Does the Research Actually Tell Us?

The scientific literature on photobiomodulation has grown substantially, but it is important to distinguish between promising evidence and definitive clinical conclusions.

Research supports several biologically plausible mechanisms for PBM, including effects on mitochondrial function, cellular signaling, oxidative stress, inflammation-related pathways, and tissue repair. [1,3]

Clinical studies have also reported potential benefits in areas such as skin appearance and exercise recovery. [2,4,5]

At the same time, study protocols vary considerably in wavelength, irradiance, dose, treatment frequency, and device design. This makes it difficult to apply the results of one study universally to every light therapy device.

Therefore, the most scientifically responsible approach is to consider:

wavelength + dose + treatment protocol + target tissue + quality of evidence

rather than focusing on wavelength alone.

How to Use Light Therapy Responsibly

When selecting a red or near-infrared light therapy device, consider more than the number of LEDs or the appearance of the device.

Look for clearly stated:

• Wavelengths
• Irradiance
• Treatment distance
• Recommended session duration
• Intended application
• Safety instructions

Following the manufacturer's recommended protocol is important because PBM follows a dose-response relationship, and excessive exposure is not necessarily more effective.

Light therapy should also not be presented as a replacement for professional medical diagnosis or treatment when someone has a medical condition.

The Bottom Line

Red light therapy and near-infrared therapy are closely related but serve different roles within the broader field of photobiomodulation.

Red light, particularly around 630–660 nm, has been extensively studied for skin and superficial tissue applications.

Near-infrared light, including wavelengths around 810–850 nm, is commonly investigated for applications involving deeper tissues, including muscle recovery and musculoskeletal health.

The difference is ultimately about more than color. Wavelength, dose, irradiance, exposure time, and tissue characteristics all influence the biological response.

For people interested in combining visible red and near-infrared exposure, dual-wavelength devices offer a practical way to incorporate both into one routine. The WECCT Red Light Therapy Mat with 660 nm Red Light and 850 nm Near-Infrared Light is one example of a full-body device built around this dual-wavelength approach.

As research continues to develop, the most useful way to understand photobiomodulation is not to ask which wavelength is universally “best,” but rather:

Which wavelength, dose, and treatment protocol are most appropriate for the intended application?

References

1. Hamblin MR. Mechanisms and applications of the anti-inflammatory effects of photobiomodulation. AIMS Biophysics. 2017;4(3):337–361.
This review discusses proposed mechanisms through which photobiomodulation may influence inflammation, mitochondrial activity, oxidative stress, and cellular signaling.

2. Wunsch A, Matuschka K. 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. 2014;32(2):93–100.
A controlled human study examining the effects of red and near-infrared light on several measures of skin appearance and collagen-related changes.

3. Chung H, Dai T, Sharma SK, Huang YY, Carroll JD, Hamblin MR. The nuts and bolts of low-level laser (light) therapy. Annals of Biomedical Engineering. 2012;40:516–533.
A widely cited review covering PBM mechanisms, wavelengths, dose-response relationships, and biological effects.

4. Stausholm MB, Naterstad IF, Joensen J, et al. Efficacy of low-level laser therapy on pain and disability in patients with knee osteoarthritis: systematic review and meta-analysis of randomised placebo-controlled trials. BMJ Open. 2019;9.
A systematic review and meta-analysis evaluating photobiomodulation-related approaches in knee osteoarthritis.

Reference source: Red Light Therapy vs Infrared: Wavelengths, Benefits & Applications