Red light therapy has quickly become a hot topic in the health and wellness industry. Its potential benefits for tissue healing, pain reduction, and skin health have generated significant Interest throughout the scientific community. Hundreds of wellness companies now offer a range of red light therapy treatments and at-home devices.
Within the field of red light therapy, the differences and applications of pulsed vs. continuous light continue to be nuanced discussions. Some people argue that the intermittent nature of pulsed light stimulates better tissue healing while others argue that the steady exposure provided by continuous light provides more consistent benefits.
With the debate far from settled, this article will explore pulsed vs. continuous light in more detail. We’ll look at what each method is, the supporting studies, and the consensus for each. Furthermore, we’ll explain why the Move+ is classed as pulsed red light therapy, and why this was important to Kineon.
So, is pulsing red light therapy better? First, let’s take a look at the key takeaways.
Pulsed vs Continuous Red Light Therapy: Key Takeaways
- Overall, pulsed and continuous PBM seem to perform somewhat similarly, with a tendency for pulsed to perform slightly better. While many studies do show a difference in outcome measures when pulsed light is used, they’re yet to clearly define the mechanisms responsible. While there certainly does seem to be a difference, the effect size doesn’t appear huge.
- Pulse frequency may be more important for transcranial applications as different brain waves operate in different frequency regimes, and there could be a coupling effect.
- Tissues may be less prone to overheating when using pulsed light. Therefore, you may be able to use higher power densities which allows deeper tissue penetration. This may lead to better benefits at and around the target muscles and tendons.
- The intermittent nature of red light therapy pulses may be better for the movement of ions. As light is pulsed, the brief ‘on’ and ‘off’ periods may lead to more active cell stimulation, increasing ion movement across cell membranes. This is vital for enzyme activation and cell signaling pathways.
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Pulsing is often investigated in animal studies with laser emitters, so it is even harder to say for sure with LED devices. We can’t say for sure if lasers and LEDs will perform the same way. Therefore, more research is needed before definite conclusions can be drawn.
With many experts and scientists still unsure of the specific reasons why pulsed light may or could be better, it’s useful to read and learn from multiple knowledge bases.
Bart Wolbers provides an excellent breakdown in his pulsed red light article. In this, he discusses the current state of research and dissects 15 random studies relating to pulsed vs. continuous red light therapy.
Why pulsed red light therapy is a hot topic right now.
In recent years, pulsed red light therapy has become a hot topic in the health and wellness community. This is as people continue looking for effective, non-invasive ways to improve their general health and well-being.
The recent focus on pulsed red light therapy largely stems from its method of light delivery. With this, what does pulsing red light therapy do?
Instead of the continuous light exposure commonly associated with red light therapy, pulsed light is delivered in intermittent bursts. This creates ‘on’ and ‘off’ periods, meaning that at different time intervals, they’ll either be light emitted or light not emitted.
This unique administration method has sparked renewed interest in the potential benefits that pulsed light may have over continuous. To get a better idea of pulsed red light therapy, let’s quickly take a look at when it first gained Interest.
The interest in pulsed red light therapy started back in 2010 with Dr. Micheal Hamblin. At the time, Dr. Hamblin was an associate professor at Harvard Medical School and one of the preeminent experts on light therapy.
With the field of light therapy still developing, Dr. Hamblin worked with a team of doctors and scientists, aiming to find the most effective low-laser light therapy application method. In their study, they compared pulsed light vs. continuous light, performing a rigorous analysis for each.
In the author's conclusions, pulsed light was declared as the better light administration method. In the study, published in the July 2010 issue of Lasers in Surgery and Medicine, here’s what the authors wrote:
“The review of the literature indicates that overall pulsed light may be superior to continuous wave light with everything else being equal.”
In the years following, this study's conclusion has widely been interpreted that pulsed light is better than continuous. Therefore, pulsed light should be used for different light therapy types, including LEDs.
However, here’s the caveat. The original study only applied to lasers and not LEDs. That brings us to the modern day, where debate continues regarding the better method and how far we can apply scientific results.
In recent years, the popularity of red light therapy in general has skyrocketed, and with the amount of devices and products available, many companies are looking for ways to differentiate their product. Pulsing vs non-pulsed is one way to do that, and this is being used as a selling point to customers. With this in mind, many customers are looking to find out for themselves what the real deal is here, and if it really matters.
To help you navigate the numerous brand claims regarding red light therapy, we’ve taken a look at the science behind both application methods. Take a look at our general thoughts on these two key studies, and if you’ve got time, read the full search using the links provided.
What the science says about pulsed vs continuous red light therapy.
Study 1: Photobiomodulation with Pulsed and Continuous Wave Near-Infrared Laser (810 nm, Al-Ga-As) Augments Dermal Wound Healing in Immunosuppressed Rats
Read the full research: https://pubmed.ncbi.nlm.nih.gov/27861614/
Key findings about pulsed and continuous light:
- 10Hz was shown to be superior to both continuous and 100Hz
- Many metrics observed
- 10Hz winner for nearly all metrics
- Still pretty similar to continuous and 100Hz, which all performed way better than control
Study strengths:
This study did a great job of keeping all of the variables besides pulse frequency constant, which allows us to accurately compare between the strategies. For example, wavelength, spot size diameter, total energy, illumination time, and more parameters were kept constant. For you electronics/photonics nerds out there, the duty cycle was also kept the same for the 10Hz and 100Hz groups at 50% which is an additional parameter that often isn’t considered. Peak power was also kept constant between the two.
Another benefit of this study is the somewhat simple model, and the benefits that come with animal models. This study looks at wound healing in a rat model, and as the laser is non-contact and on the back, establishing a placebo is not difficult. This study also used many different modalities to assess therapeutic outcomes, such as a CCO (cytochrome c oxidase) activity assay, and TNF-alpha (a pro-inflammatory cytokine) assay, as well as Western Blotting and other techniques to investigate a variety of growth factors and other biomarkers. Although sad, a strength of rat model studies is the opportunity to perform histology, which provides additional data.
Study limitations and challenges:
This study was very well thought out, such that it is hard to find clear challenges. However, as with any animal study, there is the key limitation that animal results are not always indicative of what will happen in humans.
Our thoughts on Photobiomodulation with Pulsed and Continuous Wave
Near-Infrared Laser (810 nm, Al-Ga-As) Augments Dermal Wound Healing in Immunosuppressed Rat
This study shows that 10Hz outperformed both continuous and 100Hz photobiomodulation strategies for dermal wound healing in rats, and showed this with many different investigative modalities. While studies like this have been attempted in humans, yours truly is not aware of any that both took such care with reducing variables and with having such a wide arsenal of investigative tools. While this does not prove anything in regards to what is best in humans, it certainly has a clear suggestion.
Study 2: Pulsed transcranial photobiomodulation generates distinct beneficial neurocognitive effects compared with continuous wave transcranial light
Read the full research: https://pubmed.ncbi.nlm.nih.gov/37668791/
Key findings
- Pulsing matters in transcranial PBM applications in humans.
- Generally 40Hz outperformed continuous, which outperformed 100Hz.
- Gamma waves were affected by PBM treatment
- Humans, especially human brains, are hard to study!
Study strengths:
One of the key strengths of this study is that this work is done on the human brain. As far as important and complicated systems go, the brain is king. It is also great that the authors tested out not just one pulse frequency, but both 40 Hz and 100Hz, along with continuous and sham. This gives a much stronger comparison than simply pulsed vs continuous. Another strength of this study is that it is immediately applicable as it was conducted in humans. Also, the measurements were all non-invasive (EEG and performance based testing) which allows for easier repetition.
Study limitations and challenges:
The human brain is complicated, and it can only be expected that results in studying it will be as well. While this study did see statistically significant changes, there were a lot of trends that could be observed in the raw data that did not quite meet the mark for statistically significant. While there are benefits to not using molecular assays, they would provide an excellent objective backdrop to base this data on. The authors themselves conclude, “Effects of PW photobiomodulation on CCO oxidization, cerebral oxygenation, brain hemodynamic, brain connectivity, etc. are worth further investigating”.
Our thoughts on this study
We think this study is great as it takes results that have been shown in-vitro and in animal models, and takes them to the human brain. In summary, 40 Hz was the winner, with continuous in second and 100Hz in third. While this is not set in stone, this does seem to be a repeating observation, with the 5-50Hz frequency region performing best. The data presented in this paper is not the kind of results where you look at it and say, “Wow, I have never been more convinced.” But it certainly does consistently show statistically significant trends, obtained with a variety of measurement strategies. This article is a great piece of the puzzle in showing that pulsing does indeed impact efficacy.
With the science in mind: why we like pulsed red light therapy over continuous.
With potential benefits for both application methods and debate still regarding the specific research applications, here’s why we chose pulsed red light therapy over continuous.
While both clearly have their merits, our decision came down to the therapeutic outcomes and goals we’re looking to achieve.
Pulsed light is said to stimulate cellular processes more effectively, promoting tissue repair and healing. The intermittent nature of pulsed light is thought to better trigger increased mitochondrial activity, one of the key focus mechanisms we aim to target. Furthermore, the potential deeper tissue penetration means that pulsed red light therapy may be better for deeper tissue healing and muscular treatments.
With these in mind, pulsed red light therapy may be better suited for inflammation, pain, and deep tissue work. These are three of the key focus areas we aim to address with our Move+ device. We’ll discuss this more in the next section.
Why the Move+ is a pulsed device.
The Move+ is a pulsed device. We made it this way because:
- After a very thorough look at the data, we’ve observed that the roughly 10-60Hz pulse range performs better or similar in academic studies compared to continuous emission.
- Pulsing further avoids localized thermal heating which can reduce PBM efficacy.
- The intermittent nature of pulsed light may better activate cellular processes to promote tissue repair and healing.
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Pulsed light may be able to offer deeper penetration depths, making it well-suited to deep treatments.
Even with this, there are still potential drawbacks and caveats to consider. We want to present an impartial view so you’re able to make the right informed choice. As the debate continues, some of these will hopefully be properly addressed.
With this, is pulsing needed for red light therapy? Is there a notable difference between pulsed vs. continuous light?
The mechanisms why pulsing may be better need further research. While a difference seems to exist, we can’t draw definite conclusions. For now, we must go off the limited scientific studies. Furthermore, more research using LEDs is definitely needed, with most of the current data focusing on solely lasers. If these concerns can be addressed, we’ll likely get a better picture of the actual effect size and what it means.
For more articles on red light therapy, read:
- Red Light Therapy 101: Benefits, Side Effects, Risk & How to Use It
- Red Light Therapy At Home For Pain: Everything You Need To Know
- Red Light Therapy Benefits For Pain Relief
- Red Light Therapy And Distance From Your Skin: How Far Should You Be?
- Can Red Light Therapy Damage Your Eyes? Safety Tips For Red Light Therapy At-Home
References
- https://pubmed.ncbi.nlm.nih.gov/33471046/
- https://pmc.ncbi.nlm.nih.gov/articles/PMC5523874/
- https://pubmed.ncbi.nlm.nih.gov/37522497/
- https://pmc.ncbi.nlm.nih.gov/articles/PMC8436040/
- https://link.springer.com/article/10.1007/s10103-023-03865-4
- https://pubmed.ncbi.nlm.nih.gov/16942425/
- https://pubmed.ncbi.nlm.nih.gov/23982719/
- https://pmc.ncbi.nlm.nih.gov/articles/PMC7356229/
- https://www.lighttherapyinsiders.com/red-light-therapy-pulsing/
- https://pmc.ncbi.nlm.nih.gov/articles/PMC2933784/
- https://pubmed.ncbi.nlm.nih.gov/27861614/
- https://pubmed.ncbi.nlm.nih.gov/37668791/
- https://pmc.ncbi.nlm.nih.gov/articles/PMC5844808/
- https://www.sciencedirect.com/science/article/pii/S2666469023000386
- https://pmc.ncbi.nlm.nih.gov/articles/PMC3196530/
- https://kineon.io/blogs/news/why-red-light-therapy-is-so-popular
- https://kineon.io/blogs/news/photobiomodulation-and-inflammation-reduction
