top of page

Discover the Science of Light Therapy; Part 3 - Decoding the Wavelengths in Photobiomodulation

Welcome back to the third and final part of our series on the powerful benefits of photobiomodulation therapy (PBMT). In previous chapters, we tackled the differences between laser and LED light as well as an overview of how PBMT works and its benefits.

Different colored wavelengths of light

In this last chapter, we will explore the impact of fluence rate and light wavelengths on PBMT, and how to choose the right one for the best results.

Introduction to Key Concepts of PBMT: The Fundamentals

In PBMT, "fluence rate" is a key term. Fluence rate refers to the amount of light energy that is being delivered to a certain area of skin over a specific period of time. Imagine you are pouring a bottle of water onto a plant. The fluence rate would be like how fast you're pouring that water.

Sunlight diffused under water

In the context of how deep light goes into the skin, fluence rate becomes very important. Different wavelengths, or colors, of light penetrate the skin at different depths. Just like sunlight can't reach very far underwater, not all light can reach deep into our skin.

But here's where the fluence rate comes in. If you increase the fluence rate (like pouring the water faster), more light energy gets delivered to the skin in less time. So, more of the light can reach deeper into the skin before it's all absorbed at the surface.

However, there is a balance to find because a fluence rate that is too high might overwhelm the skin's cells and not give them enough time to respond properly. So, in photobiomodulation research, scientists try to find the best combination of light color (wavelength) and fluence rate to help the body heal itself.

You can maximize the effectiveness of your sessions and get the best outcomes by understanding how the fluence rate and light wavelength affect PBMT.

The Research on Photobiomodulation Therapy

In this study, by Louise Finlayson, Isla R. M. Barnard, Lewis McMillan, Sally H. Ibbotson, C. Tom A. Brown, Ewan Eadie, and Kenneth Wood, the authors present the first study reviewing the impact different wavelengths of light have on the penetration depth of light in skin using the wavelength range 200–1000 nm. They also looked at how different factors, like incident angle, affect penetration depth and how the thickness of the skin affects the results.

Illustration of the six model skin layer
The model consists of: 1. Outermost layer of Epidermis -Stratum Corneum 2. Epidermis 3. Melanin Layer or Melanized Epidermis 4. Basal Layer 5. Dermis 6. Subcutaneous Fat. The skin model used in the study was based on a 6-layer model with a subcutaneous fat layer.

The skin model used in the study was based on a 6-layer model with a subcutaneous fat layer. It was labeled as Type I skin based on the Fitzpatrick Scale. The layers were assigned wavelength-dependent properties based on the layer where they were located.

Figure 2: Plots the depth as a function of the wavelength delivered into the upper layers of the skin through direct and diffused light sources
Figure 2: Plots the depth as a function of the wavelength delivered into the upper layers of the skin through direct and diffused light sources

This diagram shows the upper layers of the skin model and plots the depth of each wavelength that was delivered to the skin. The left diagram illustrates the depth of the direct light wavelengths and the right diagram shows the depth of the diffused light wavelengths.

Illustration that plots showing the depth as a function of the wavelength delivered into the dermal and subcutaneous layers of the skin through direct and diffuse sources
Figure 3: Plots showing the depth as a function of the wavelength delivered into the dermal and subcutaneous layers of the skin through direct and diffuse sources

The depth that light can reach at each wavelength for both direct and diffuse incident light is displayed in Figures 2 and 3. The data revealed that the penetration depth increases with increasing wavelength until water absorption starts to take effect in the infrared (IR) region, where it then decreases. At this point, a coherent, collimated, and monochromatic light source could overcome the water barrier. A larger percentage of the direct incident light can reach further into the skin than the diffuse incident light.

Choosing The Best Photobiomodulation Therapy Treatment

We can see from the information above how different light wavelengths enter the skin and travel to various depths, potentially affecting the fluence rate at different skin depths. Wavelengths aren’t the only factor to consider when looking at treatment options. There are other factors that can have an impact on the overall treatment. For example;

Light Intensity: This is the amount of light energy delivered per unit area. Higher intensity means more energy is delivered, increasing the fluence rate.

Treatment Duration: The length of the therapy session also impacts the fluence rate. Longer exposure times deliver more light energy, raising the total fluence.

Distance from the Light Source: The fluence rate decreases as the distance from the light source increases due to the spreading of light rays. Positioning the light source closer to the skin can increase the fluence rate.

Skin Type and Condition: Skin characteristics, including its color (melanin content) and thickness, can affect the absorption and scattering of light, thus impacting the fluence rate. Conditions like inflammation or wounds can also change how light is absorbed and scattered in the skin.

Pulse Structure: Photobiomodulation devices can deliver light continuously or in pulses. Some research suggests that pulsed light may have different biological effects than continuous-wave light, potentially affecting the effective fluence rate.

Device Quality and Calibration: The quality of the PBMT device and how accurately it's calibrated can affect the fluence rate. If the device is not delivering the light intensity it's supposed to, the fluence rate will be off.

Light Beam Width: Studies have shown that as the beam width is increased, there is an increase in the amount and depth of light penetration.

Photobiomodulation therapy is a bit like Goldilocks and the Three Bears - it's all about finding just the right fit for you. Why's that? Because different health conditions call for different types of treatment. The location and depth of the affected cells or tissues play a significant role in shaping the treatment parameters. Similarly, the severity of your condition also contributes to the therapeutic puzzle we need to solve.

At the heart of it all is the type of cellular response we aim to stimulate to kickstart healing or manage your symptoms. Think of it as tuning a radio to the right station - too little energy and you might not catch the signal (or, in this case, achieve the therapeutic effect). But crank up the volume too high, and you risk overexposure, which can actually dial back the effectiveness of the treatment.

In other words, striking the perfect balance is crucial to ensuring the treatment is as effective as possible. It's our mission to find that 'just right' for you, carefully tailoring your treatment plan to your unique needs. Because in the story of your health and wellness, we want you to have a 'happily ever after'

Illustration of the light spectrum from ultraviolet to infrared

Discovering the Best Light Wavelength for Photobiomodulation Therapy

Photobiomodulation therapy (PBMT) is also known by a few other names: low-level laser therapy (LLLT), red light therapy, or LED light therapy. But no matter what you call it, this treatment primarily uses colors from one specific part of the light spectrum – the red and near-infrared spectrums.

Why those colors? Well, light wavelengths that fall between 600 and 1000 nanometers (nm) are the superstars of PBMT. They're chosen for their unique ability to dive deep beneath your skin and tissues, reaching the places where they can do the most good. These wavelengths also make the biggest splash when it comes to influencing cellular functions, thanks to their close relationship with the star player in the PBMT process: cytochrome c oxidase (CcO). (Remember our chat about CcO last week?)

On the other end of the spectrum, we have wavelengths below 600 nm. These are the violet and blue lights of our rainbow, with wavelengths ranging from 300 to 500 nm. While they have their own charm, they can't dive as deep into the tissues as their red and near-infrared siblings. But don't dismiss them just yet. While they might not typically be classified as PBMT, they can still have their own biological benefits.

So when you're talking about true-blue (or should we say true-red?) PBMT, you're looking at wavelengths within the 600–1000 nm range.

Illustration of the depth of light based on light wavelength

Top 5 Wavelengths in Photobiomodulation Therapy and Their Benefits

In PBMT, different wavelengths of light are used to achieve specific therapeutic effects. Here are five commonly used wavelengths and their associated benefits:

630 - 633 nm (Red Light)

This wavelength is especially beneficial for skin health. It is known for its ability to stimulate collagen production to aid in anti-aging. It helps with wound healing, reduces inflammation, and improves circulation.

660 nm (Red Light)

This wavelength is absorbed well by skin tissue, making it ideal for treating skin conditions. It's used to boost collagen production, promote skin rejuvenation, reduce wrinkles, and accelerate wound healing. It is also known for its anti-inflammatory properties and can be used to improve skin tone and texture.

810 - 830 nm (Near-Infrared Light)

This wavelength penetrates deeper into tissues, making it easily absorbed by the body's cells. This can improve cellular energy production. It's commonly used for pain relief, reducing inflammation, and promoting recovery in muscles, joints, and tendons, as well as having the potential for neuroprotective effects. This wavelength is also widely used to stimulate the healing of damaged tissue. It's often used for conditions such as arthritis, muscle recovery, and various types of pain management.

850 nm (Near-Infrared Light)

This wavelength has even greater tissue penetration and is commonly used for treating muscle recovery, joint pain, and inflammation, as well as for brain health applications due to its ability to penetrate the skull. Commonly used to improve circulation.

940 - 980 nm (Near-Infrared Light)

This wavelength has the deepest penetration and is often used for conditions affecting bones and joints as well as for deeper tissue healing. Has been shown to improve cognitive function as well as boost cellular function. Often used in treating conditions like nerve repair and pain management.

Just a friendly reminder, light therapy isn't a one-size-fits-all solution. The success of a particular wavelength can be influenced by various factors, including the specific ailment you're hoping to treat, the device used for the treatment, and even personal traits like your skin type. It's a beautifully complex process! To ensure you're getting the most from your PBMT journey, we always advise you to have a chat with a healthcare provider before you begin. They can guide you toward the treatment plan that will work best for you.

A Photobiomodulation Therapy Success Story

Our client, Margaret, stopped me in the wellness store one afternoon to share her story. She told me that she has been dealing with painful arthritis in her foot for several years. She had taken medicines that didn't work, creams that didn't help, and injections that provided brief relief but weren't lasting. That's when she discovered PBM at Proactive Massage + Bodywork.

After four treatments, the pain was completely gone. After six treatments, both the swelling and the pain were gone. Margaret was so excited to tell me that she couldn't believe that a painless 20-minute treatment would do this much good. She told me, "It’s amazing! It's like I got my life back because the arthritis pain is completely gone and I'm back to my normal routine. My only regret is that I didn't know about this sooner!

Margaret combines her PBM sessions with massage therapy to keep active and reduce the risk of her arthritis returning and slowing her down. That's the power of PBMT in action!

Start a Bright New Chapter With Proactive Massage + Bodywork and PBMT

That's a wrap on our enlightening three-part series all about the transformative power of photobiomodulation! We trust that this journey has highlighted the impressive potential of PBMT for you. Armed with this newfound knowledge, you're now well-equipped to have a meaningful conversation with your healthcare provider about your treatment possibilities, helping you step confidently towards your wellness goals. Check out our post on FAQ's of PBMT for answers to some of the most asked questions about PBMT.

Remember, like any therapy, consistency and regularity are the keys to a successful outcome.

Ready to start your wellness journey? Reach out to the team at Proactive Massage + Bodywork at (804) 559-7990 or drop us a line at to book your appointment.

Let the rejuvenating power of light therapy usher in a vibrant new chapter in your life.


Do you have any questions or topics you'd like us to cover? Leave a comment below, and we'll make sure to address them in future articles.

Collage of service pictures from Proactive

Proactive Massage + Bodywork is proud to offer full-body treatments using our state-of-the-art PBM Light Therapy Bed.

PBMT is a non-invasive and painless treatment that uses specific wavelengths of light to stimulate the body's natural healing processes and improve a variety of conditions.

During a full-body PBMT treatment, you will lie in the enclosed light bed and be completely surrounded by LED lights directed at your skin. The lights are emitted at various wavelengths, including 630nm, 660nm, 810nm, 850nm, and 940nm, each of which offers unique benefits to the body.

A full-body PBMT treatment can help to improve skin tone and texture, reduce inflammation, stimulate collagen production, and promote healing in the body. It is a safe and effective treatment option for a wide range of conditions and can be used as a standalone treatment or in combination with other therapies.


  • Ash, C., Dubec, M., Donne, K., & Bashford, T. (2017). Effect of wavelength and beam width on penetration in light-tissue interaction using computational methods. Lasers in medical science, 32(8), 1909–1918.

  • What the PBM Foundation Does - PBM Foundation. (2023). Retrieved 7 June 2023, from,PBM%20equipment%20is%20FDA%20approved

  • Finlayson, L., Barnard, I.R.M., McMillan, L., Ibbotson, S.H., Brown, C.T.A., Eadie, E. and Wood, K. (2022), Depth Penetration of Light into Skin as a Function of Wavelength from 200 to 1000 nm. Photochem Photobiol, 98: 974-981.

  • Serrage, H., , Heiskanen, V., , Palin, W. M., , Cooper, P. R., , Milward, M. R., , Hadis, M., , & Hamblin, M. R., (2019). Under the spotlight: mechanisms of photobiomodulation concentrating on blue and green light. Photochemical & photobiological sciences : Official journal of the European Photochemistry Association and the European Society for Photobiology, 18(8), 1877–1909.

  • Zein, R., Selting, W., & Hamblin, M. R. (2018). Review of light parameters and photobiomodulation efficacy: dive into complexity. Journal of biomedical optics, 23(12), 1–17.

  • Kitchen, L. C., Berman, M., Halper, J., & Chazot, P. (2022). Rationale for 1068 nm Photobiomodulation Therapy (PBMT) as a Novel, Non-Invasive Treatment for COVID-19 and Other Coronaviruses: Roles of NO and Hsp70. International Journal of Molecular Sciences, 23(9), 5221.

  • Fuchs, C., Schenk, M. S., Pham, L., Cui, L., Anderson, R. R., & Tam, J. (2021). Photobiomodulation Response From 660 nm is Different and More Durable Than That From 980 nm. Lasers in surgery and medicine, 53(9), 1279–1293.

  • Additional Research


Rated 0 out of 5 stars.
No ratings yet

Add a rating
bottom of page