What Is Red Light Therapy? The Basics Of Red Light Therapy And Photobiomodulation

Red light therapy is also called Low-level laser therapy (LLLT) or Photobiomodulation. It involves the use of light, typically from a low-power laser or LED ranging from 1mW to 500mW, to stimulate tissue regeneration, reduce inflammation, and alleviate pain. The light used in LLLT is usually within the red or near-infrared (NIR) spectrum (600nm – 1000nm) and has a power density (irradiance) between 1mW and 5W/cm².

What Does Red Light Therapy Do?

Red light therapy is a treatment that uses specific wavelengths of light to stimulate cellular activity and promote healing. This non-invasive therapy can be used to address a variety of health concerns, including pain management, inflammation, and wound healing.

 

Unlike other laser-based medical procedures, red light therapy does not work through heat or tissue destruction. Instead, it operates via a photochemical process, similar to photosynthesis in plants, where the absorbed light triggers chemical changes in the cells.

 

When red light therapy is applied, the light penetrates the skin and is absorbed by mitochondria, the energy-producing organelles within cells. This absorption triggers a cascade of biochemical reactions that can:

Increase cellular energy: Red light therapy stimulates the production of adenosine triphosphate (ATP), the primary energy currency of cells.

Reduce inflammation: By modulating the activity of inflammatory cells and signaling molecules, red light therapy can help decrease inflammation and associated pain.

Promote tissue repair: Red light therapy can enhance the growth and regeneration of damaged tissues by stimulating the production of growth factors and other proteins involved in healing.

Improve blood flow: Red light therapy can increase blood flow to the treated area, which can help deliver oxygen and nutrients to damaged tissues and remove waste products.

Modulate the immune system: Red light therapy can influence the activity of immune cells, helping to balance the body's inflammatory response and promote healing.

For a full list of the biomechanics stimulated by red light therapy, read our blog on “How Does Red Light Therapy Work? The Biomechanisms Explained”

 

It is becoming more and more clear that both local and systemic mechanisms are involved. Locally, red ight therapy helps reduce swelling and lower levels of oxidative stress and inflammatory markers. Additionally, light therapy can also benefit distant tissues and organs throughout the body.

What Is Red Light Therapy Good For?

Numerous studies involving animals and clinical trials have shown that red light therapy can be very effective in treating various diseases and injuries, making it useful for both chronic and acute conditions. 

 

Red light therapy can improve the formation of new blood vessels, promote healing, and increase collagen production, which aids in healing both recent and long-term wounds. 

 

Additionally, it can help repair deeper tissues, such as nerves, tendons, cartilage, bones, and even internal organs. 

 

Red light therapy is also effective in reducing pain, inflammation, and swelling resulting from injuries, degenerative diseases, or autoimmune conditions. 

 

Its positive impact on recovery after injuries or blood flow issues in skeletal and heart muscles has been confirmed in various animal studies. Furthermore, LLLT has been used to help reduce damage after strokes, traumatic brain injuries, and spinal cord injuries in both animals and humans.

What Is Photobiomodulation?

Light therapy was essentially rediscovered when scientists observed that low-power laser light positively impacted wound healing and hair regrowth in mice. The term photobiomodulation (PBM) has now become the preferred terminology to describe the therapeutic use of low levels of red and/or near-infrared (NIR) light to address a variety of diseases and conditions. Previously referred to as "low-level laser or light therapy," the name was changed to accommodate the growing use of LEDs, the potential for both inhibition and stimulation, and to clarify the vague nature of the term "low level."

 

In recent years, the use of photobiomodulation (PBM) in clinical settings has been growing rapidly. The introduction of affordable large-area LED arrays has made this technology more accessible, replacing expensive small lasers that carry a risk of eye damage.

 

Improved understanding of how PBM works at the molecular and cellular levels has provided a solid scientific basis for its application in treating various diseases. Many patients, frustrated with traditional medications that often come with unpleasant side effects, are seeking alternative and complementary therapies for more natural solutions. 

Low-Level Lasers vs. LED Red Light Therapy

The key difference between low-level lasers and LEDs in photobiomodulation (PBM) lies in their dosing and depth of tissue penetration.

 

LEDs are a great choice because they can be applied directly on the skin. Used in wrap devices, they an treat the target area from all angles, leading to more predictable treatment outcomes. While they do not penetrate as deep as lasers, their penetration is great for the treatment on knees, feet, hands, shoulder & neck.

 

Low-level lasers (class 3 lasers) offer deeper penetration, which is beneficial when targeting areas beneath layers of fat, such as the abdomen or back. The concentrated and focused light of lasers provides a more consistent dosage. Additionally, lasers tend to be more durable than LEDs, making them a more reliable option for long-term use in PBM treatments. However, laser therapy devices can often only treat a small area, or come in bulky devices (i.e. panels) that do not allow for treatment of the target area from all angles.

 

Class 4 lasers, also known as high-intensity laser therapy (HILT), primarily works by heating tissues to provide temporary pain relief, not by stimulating tissue healing as PBMT does.  Class 4 lasers typically use a 980 nm wavelength, which is strongly absorbed by water molecules. This absorption generates heat, much like the far-infrared lamps used to keep food warm in restaurants. To prevent burns, Class 4 lasers require the device to stay in constant motion and at a distance from the skin, similar to the function of a deep heating pad. In some cases, Class 4 lasers may use red or near-infrared wavelengths, which are also used in PBMT. However, they emit a very wide beam over a large surface area and must be kept at a distance to avoid overheating. As a result, the power and dosage delivered to the skin can match those used in PBMT with Class 3B lasers or LEDs. However, up to 85% of the light is reflected away, meaning only a small portion penetrates the skin and reaches the tissues. Most clinical research on PBMT involves Class 3B lasers or LEDs in direct contact with the skin, which reduces reflection and maximizes light penetration. This technique cannot be achieved with Class 4 lasers due to their high power and associated burn risk, limiting their ability to deliver true photobiomodulation.

 

Both technologies have their unique strengths, and their application depends on the specific treatment area and therapeutic goals.

Why Is Red Light Therapy Not Used In Mainstream Medicine?

The use of low levels of visible or near-infrared light to reduce pain, inflammation, and edema, promote healing in wounds, deeper tissues, and nerves, and prevent cell death and tissue damage has been recognized for over forty years, following the invention of lasers. Despite numerous reports of positive results from in vitro studies, animal models, and randomized controlled trials, low-level laser therapy (LLLT) remains controversial in mainstream medicine.

 

The biochemical mechanisms responsible for its beneficial effects are not fully understood, and the challenge of selecting the appropriate illumination parameters—such as wavelength, fluence, power density, pulse structure, and timing—has led to the publication of both positive and negative studies. A biphasic dose response is often observed, where lower levels of light produce a more effective stimulus for tissue repair than higher levels, a pattern described by the Arndt-Schulz curve.

The Biphasic Dose Response

Like other forms of treatment, LLLT has its own "active ingredients" or therapeutic elements (irradiation parameters) and a "dose" (the duration of irradiation). In general, dosing the light energy and irradiation properly is crucial for effective results with photobiomodulation. Too little light and it doesn't stimulate change, too much light and this can negate the benefits. This is known as the biphasic dose response. “A biphasic dose response has been frequently observed where low levels of light have a much better effect on stimulating and repairing tissues than higher levels of light.” [1].

Red Light Therapy Panels vs. Belts/Wraps

Red light therapy panels and red light therapy belts/wraps both offer significant benefits, but they differ in their application and effectiveness.

 

As learned in the biphasic dose response, dosing the light energy and irradiation properly is crucial for effective results with photobiomodulation. Too little light and it doesn't stimulate change, too much light and this can negate the benefits.

 

Because of their design, lasers are difficult to work into a wrap/ belt device which is why they are most commonly used in panels, while LEDs are used in belts/ wraps.

 

Panels are ideal for full-body treatments, which makes them highly effective for regeneration and recovery. On the other hand, panels are big and bulky and do not allow for targeted treatment directly on the skin. 

 

Using the device at skin-level, however, allows you to experience the best possible results because the device consistently delivers the right dosage of light to your internal tissue.That’s why belts/ wraps are great for targeted treatment of specific areas. This is because by wrapping around a nerve, joint or muscle you get 360° coverage which allows for better light penetration and thus for more effective results and quicker healing effects. Belts/ wraps, however, are limited in their ability to provide full-body coverage.

 

Up until now, there has always been a trade-off between the two devices. Either, you could choose panels using lasers for deeper penetration that do, however, lack the benefit of 360 degree penetration of a localized area for targeted relief. Or you could opt for a belt/ wrap device that has the benefit of 360 degree penetration at skin level for optimal dosing of light, that do however lack the deep penetration of lasers to reach organs and tissues behind layers of fat such as the abdomen and back.