“How is the Joovv Light different than Sauna Space?” In full transparency, I was a bit surprised when we first started hearing that question from some of our prospective customers. Why? Well, sauna-based therapy has a distinctly different mechanism of action than photobiomodulation.
But, we started getting the same type of question more and more. So much so that we felt the need to clear up some confusion. To sort of set the record straight, if you will. Therefore, in the following article, we’ll cover the following:
- What is photobiomodulation (PBM) and how does it work?
- How is PBM different than sauna-based therapy?
- Why infrared (IR) heat lamps don’t deliver the right wavelengths for the purposes of PBM.
- Why the subpar irradiance of IR heat lamps doesn’t meet the standard for PBM therapy.
What is Photobiomodulation and How Does it Work?
In laymen’s terms, photobiomodulation - or light therapy - is the study of specific wavelengths of light and their biochemical effects on human cells. It’s an entire sub-specialty of medicine, has been around since the mid-1900’s, and is supported by thousands of published clinical studies. In fact, we’re fortunate to have Dr. Michael Hamblin, arguably one of the world’s leading photobiomodulation researchers, on our scientific advisory board.
Specific to clinical data, extensive published research has demonstrated that a relatively narrow band of wavelengths have the greatest positive effects on cellular processes. (1) In fact, as we've discussed before, the ranges that have been proven to be most effective are from 630 nm to 670 nm, and from 810-880 nm.
When it comes to producing clinically-relevant results with photobiomodulation, a critical factor is the intensity - or irradiance - of the light source, typically measured in mW/cm2. A robust amount of research has shown the total energy delivered to the body typically needs to be 4-5 Joules/cm2 at a minimum. Some clinical studies have even shown that higher amounts, approaching 100 Joules, are needed in order to treat deeper tissue. The intensity of the light directly impacts the time required for treatments. For example, a device with 1/3 the irradiance would take 3 times as long to get the same results. Imagine filling up your water bottle from a dripping faucet. Yes, you will eventually fill it up, but you’ll waste a lot of time in the process.
For these reasons, clinical-grade irradiance of 50-100 mW/cm2 is ideal. This range equates to approximately 3-6 Joules/cm2 per minute. Lower-powered devices in the 5-10 mW/cm2 range will technically work. But like a dripping faucet, it will take a very long time to receive the necessary amount of light energy for demonstrable biological benefits.
So, before we go any further, remember that specific wavelengths of light and the intensity (irradiance) of the light source are crucial factors when it comes to receiving the benefits of photobiomodulation.
How is Photobiomodulation Different than Sauna-Based Therapy?
The mechanism of action of a sauna is to induce thermal stress on the body, resulting in several biological responses, including increased heart rate and perspiration.
More specifically, when the body is subject to heat in sufficient amounts, it causes an imbalance in protein metabolism. This is an ongoing process called protein folding, whereby random protein coils transform into their normal 3-dimensional structures. In fact, we have an entire class of molecular chaperones that monitor our cells for any type of stress that disrupts this process. Specifically, a class of these chaperones, called heat shock proteins, respond to heat-induced cellular stress. By inducing heat stress on the body, the resulting activation of these heat shock proteins leads to some interesting (and clinically-proven) health benefits.
Regarding photobiomodulation, the mechanism of action is distinctly different. To better understand this, let’s consider the full spectrum of natural sunlight, as shown in the graph below. The vast majority of these wavelengths are felt as radiant heat, including UV, most of IR-A, as well as IR-B and IR-C. This is because these wavelengths are absorbed very quickly by the dermis and epidermis of our skin, resulting in the heat we feel from the sun. Because of their ability to generate heat, this is why high-quality dry saunas will typically deliver far infrared (IR-C) wavelengths.
Alternatively, with photobiomodulation, there is a narrow band of wavelengths from about 600-950 nm that can penetrate human tissue much more effectively. In published literature, this is often referred to as the infrared window - or optical window. (2) As you can see in the chart below, wavelengths below 600 nm are readily absorbed by blood. Above approximately 950 nm, water becomes the controlling factor as the absorbance quickly increases with longer wavelengths, particularly in the IR-B and IR-C ranges.
Within the optical window, scientists have discovered that certain wavelengths have a unique ability to activate cytochrome c oxidase (CCO), the last enzyme in the respiratory electron chain transport of the mitochondria. During the fourth phase of cellular respiration (oxidative phosphorylation), specific wavelengths of red and near infrared light break the bond between nitric oxide and CCO. This allows oxygen to bind to NADH, restoring the normal pathway for hydrogen ions to create the electrochemical potential that produces ATP (cellular energy). A simple way to think of this process is that photons essentially charge your cellular batteries.
So, in summary, the core mechanism of sauna-based therapy is to induce heat stress. Alternatively, photobiomodulation requires very specific wavelengths of light - at the right intensity- to enhance normal cellular function.
Why Infrared (IR) Heat Lamps Don’t Deliver the Right Wavelengths for the Purposes of PBM
As we just discussed, activating cytochrome c oxidase is critically important when it comes to photobiomodulation. With this in mind, let’s turn to the chart below, which depicts the activation of CCO at various wavelengths. As you can see, there are specific peaks of absorption in the mid-600 nm and mid-800 nm ranges. (3) However, wavelengths in the 700-730 nm range, for example, have very little biological impact because of their inability to efficiently activate CCO. (1)
IR heat lamps, like the ones in a Sauna Space, deliver a wide range of wavelengths. However, as you can see in the chart below, an incredibly small percentage of the light is actually able to activate CCO. In fact, only about 3% of the wavelengths fall in the mid-600 nm and mid-800 nm ranges. (4)
Specific to irradiance, there is no doubt IR heat lamps run hot and are definitely not safe to touch. That’s why Sauna Space (and any other distributor of heat lamps) recommends anywhere from 18-24 inches of clearance between your body and the bulb. However, irradiance is a function of the distance from the light source. And at 20 cm (about 8 inches) from an IR heat lamp, the irradiance drops down to around 10-30 mW/cm2 depending on your position relative to the center of the bulb. (4) But at 18-24 inches away, as you can see in the image below, the actual irradiance falls off significantly:
- 7.99 mW/cm2 at 12 inches
- 4.30 mW/cm2 at 18 inches
- 2.60 mW/cm2 at 24 inches
To top it off, remember that only about 3% of the energy is even effective for the activation of cytochrome c oxidase. So, as you can see, IR heat lamps are terribly inefficient for PBM therapy.
But, if the irradiance is so poor at a distance of 18-24 inches from an IR heat lamp, why do you sweat so much? Fantastic question! To address this topic, let’s go back to the aforementioned graph which displays the various wavelengths delivered from an IR heat lamp. Although they peak around 1,100 nm, the wavelengths range from about 600 - 4,000 nm. Because the majority of this energy is outside the optical window (>1,000 nm), these wavelengths are quickly absorbed due to the water in your skin tissues. For this reason, you feel the energy as radiant heat.
Conclusion: Sauna Space is a Broad Spectrum Sauna that Isn’t Ideal for Photobiomodulation
In summary, IR heat lamps deliver a broad range of wavelengths, with the majority outside of the optical window. And because the irradiance is extremely poor at the recommended treatment distance, they are a poor source of light for the purposes of photobiomodulation (light therapy). Instead, a high-quality PBM device will deliver clinically-proven wavelengths with medical-grade irradiance over a broad treatment area. If you’d like to get into the weeds, here’s an in-depth comparison of how our devices compare to other light therapy products.
Having said that, what is a product like Sauna Space good for? From our perspective, it should be viewed in the same category as other saunas. The effectiveness of IR saunas is determined by how well they deliver radiant heat to the body. This is why high-quality IR saunas utilize IR-C wavelengths (3000 nm – 1 mm), which are much more effective at generating heat. When compared to carbon emitters, heat lamps are not nearly as effective and also come with safety precautions as they are extremely hot to the touch.
However, infrared heat lamps are very inexpensive and can be found at any local home improvement store. So, if a high-quality sauna with carbon emitters doesn’t fit your budget, building a homemade sauna using IR heat lamps may be a good temporary solution.
To wrap this up, even though there is significantly more published clinical data to support the use of photobiomodulation, we firmly believe sauna-based therapy is a nice adjunct. But, just like any health-related purchase, make sure you understand the science before making any decisions.
(1) Chung H, Dai T, Sharma SK, Huang Y-Y, Carroll JD, Hamblin MR. The Nuts and Bolts of Low-level Laser (Light) Therapy. Annals of Biomedical Engineering. 2012;40(2):516-533. doi:10.1007/s10439-011-0454-7.
(2) Hamblin, M. Mechanisms of low-level light therapy. Retrieved from http://photobiology.info/Hamblin.html.
(3) Karu, T. I., Pyatibrat, L. V., Kalendo, G. S. and Esenaliev, R. O. (1996), Effects of monochromatic low-intensity light and laser irradiation on adhesion of HeLa cells in vitro. Lasers Surg. Med., 18: 171–177.
(4) Phillips. Infrared heat lamps/industrial product specification. Retrieved from http://images.100y.com.tw/pdf_file/21-PHILIPS-InfraredHeatLamp.pdf