Recently, we've published a few in-depth articles on red light therapy on this website - because the topic remains insanely popular. Examples are:
This installment, in turn, looks at how red light therapy works at a physiological level.
Many people simply don't understand why and how light affects your body at a biological/physiological level.
Because we get many questions on this topic every on a weekly or monthly basis, I've decided to begin explaining red light therapy in very simple terms, only to move to more difficult concepts subsequently.
So even if you've never heard about red light therapy before, this article explains the basics you need to know about. After reading this blog post, moreover, I also highly recommend taking a look at Alex's excellent Everything You Need To Know About Red Light Therapy blog post.
This blog post is divided into several sections. Here's the table of contents:
For a full understanding of the topic, it's best to read all sections - you might not understand everything by just reading the latter section(s).
So let's get started and dig into the topic. Here we go:
Before I dig deep into "red light therapy", let me first clarify what exactly I mean by those words...
There are many names to describe roughly the same type of therapy:
(Don't worry about the difficulty of these terms, or remembering them.)
All of these three names actually denote the same thing: using red light on your body, with the goal of affecting your health or performance.
Let's explore these options in some more detail:
First of all: red light therapy - the chosen subject of this blog post.
Even though the therapy is named "red light therapy" two types of light are actually used: 1) red light; 2) infrared light. Both types of light are also emitted by the sun.
You can see all types of light emitted by the sun in the picture below:
The light of the sun that reaches the earth's surface is a combination of infrared light, visible light, and ultraviolet light (only UVC or "ultraviolet C" does is not present in large quantities.)
If you inspect the picture above, different types of light have different wavelengths. "Nanometers" are the unit of measurement of these wavelengths - one nanometer equaling a millionth of a millimeter.
Yes, nanometers are really small.
(Another way to imagine that size is to imagine 1 micrometer as 1/1,000th of a millimeter, and 1 nanometer as 1/1,000th of a micrometer)
Ultraviolet light has the shortest wavelength, ranging from 200 to 400 nanometers. Infrared the longest wavelength in the light spectrum, being longer than 780 nanometers.
In between the 400 and 780 nanometer wavelengths, visible light is found - which is visible through your eyes. Ultraviolet and infrared light, on the contrary, are not visible through your eyes. Observe that visible light is made up of all the colors of the rainbow.
Red light therapy uses only the red part of that visible light spectrum (and sometimes some orange as well). Additionally, red light therapy uses (a small) part of the infrared spectrum.
Red light therapy thus uses:
(This method of categorizing different light colors and tying them to light wavelengths is not set in stone.)
I've emphasized the light spectrum used by red light therapy below:
That golden part of the spectrum is thus what's used in red light therapy...
Let's consider another word that's commonly used to describe "red light therapy":
Secondly, we have the word "photobiomodulation"
That sounds difficult, right?
Let's dissect that word.
The first part of the word "photobiomodulation" is "photo", which is derived from the Greek word for light. The second part of the words "bio", signifies the Greek word "bios" or life. "Modulation", thirdly and lastly, denotes change.
In very simple terms, photobiomodulation means "using light to change life".
That word photobiomodulation thus gives you insight into what red light therapy is all about: using light to influence your biology, so that you can experience certain health (or performance) benefits.
Lastly, there's the term "Low-Level Laser Therapy", or LLLT.
That sounds complex again right?
Let's break it down...
LLLT - or "Low Level Laser Therapy - simply means using low-powered lasers for (light) therapy.
The topic of LLLT brings us immediately to an interesting discussion. In my article, I'm mainly discussing LED panels for red light therapy. You can view Alex with such a LED panel here:
A panel of LEDs basically combines ten or hundreds (or even thousands) of the following LED lights:
Stacking hundreds of red and infrared emitting
LED lights on a panel - what red light therapy
is all about.
Why LEDs? Well, contrary to lasers, LEDs are very inexpensive to produce.
LEDs also work somewhat differently than lasers. Lasers emit light continuously, while LEDs don't. Instead, LED lights pulse their light, so that the light is basically switched on and off for 60 times per second.
The steady stream of light offered by lasers was long deemed to be superior to the on and off switching LEDs. For decades companies have actually not been using and promoting these red light therapy LED panels.
Companies could charge $10,000 or $15,000 for a laser product. Due to those prices, lasers were unaffordable for the general public.
And yet, lasers have become (somewhat) obsolete. Only for some very specific cases, a laser might still be beneficial. In all other cases, such as using red and infrared light for general health purposes, you don't need an overpriced laser.
It turns out that LEDs work just as well as lasers, in most cases![2-6; 288]
How do I know?
Hundreds of studies have been carried out with LEDs and proven their clinical effectiveness. Comparisons between lasers and LEDs also show that they work equally well.
The mass usage of red light therapy LED panels by regular consumers thus undercut the business model of laser companies. Laser companies do not want you to know that LEDs are just as effective, but it's already too late to stop the LED red light therapy movement now...
There's thus no need to spend thousands of dollars on a laser. You just need a good red light therapy LED panel, such as the one I've listed above.
(Advanced explanation for geeks: there is a diverging opinion on lasers. Lasers do have one potential benefit over LEDs: lasers have a continuous light output, while LEDs do not. In this very specific regard lasers can approximate sunlight better than LEDs can. Why? LEDs flicker, why lasers do not. Due to the excessively high price of full-body laser therapy, and the danger of operating lasers, I'm not recommending lasers. If lasers could be made safe to use by the general public, and inexpensive, I do believe they could (and should) replace LEDs again, to approximate the sun.)
So, what am I trying to say in this section?
I'll summarize in one sentence what this blog post is all about:
So: red light therapy LED devices use both the "red" and "infrared" part of the light spectrum, to change your biology, with the goal of improving your health and performance.
But there's more:
A big blessing of the LED red light therapy devices is that they're really safe.
If you would use lasers instead, a trained operator is needed for ensuring safety. Lasers are also inherently more dangerous qua side effects - you can easily damage someone with lasers if you don't know what you're doing.
With LED red light therapy panels, there's not much to worry about. I do want to make one disclaimer though:
Moreover, red light therapy can have side-effects as well if used improperly.
It might sound strange, but red light therapy works by putting a low level of "stress" on your body.
Let me explain...
In terms of stress, red light therapy is just like exercise.
Let's say you're running in nature to keep your body strong and healthy. If the intensity of your running sessions is too low, your body won't get stronger. If the intensity is too high, instead, you'll overtrain and your body may even get weaker after a while.
Only if you use the right intensity of exercise - an intensity that is somewhat challenging - will you get good benefits. The same is true for red light therapy: either a too low dosage or too high dosage is not beneficial, while the right dosage helps your body grow stronger and healthier.
You'll need to find the sweet spot with red light therapy (just as you do with sex).
Oh yeah: it's important to remember that red light therapy can never replace the benefits of sunlight.
Yes, I've said it time and time again:
Nothing in the world replaces sunlight exposure...
Sunlight has benefits that you cannot get from red light therapy because sunlight contains many other light frequencies that are not emitted by red light therapy devices.
When the sun is high up in the sky, ultraviolet and all the colors of the rainbow of the visible light also hit the surface of the earth, for example. Red light therapy devices do not emit any ultraviolet light or the blue, green, yellow parts of the visible light spectrum.
You thus need sunlight to have all parts of the light spectrum hit your skin and eyes. Don't sell yourself short...
Sunlight: irreplaceable -
and not just for humans...
(By the way, if you're not acquainted with the benefits of sunlight, read my free guide on that topic. Some types of ultraviolet light emitted by the sun - listed as "UVB in the earlier light spectrum illustration - creates vitamin D in your skin. You cannot get that benefit through red light therapy.)
Red light therapy and sunlight do have similarities though.
54% of the light emitted by the sun is infrared - and a few percents consist of red light.
Sunlight thus already emits red and infrared light. So why use a red light therapy device anyway?
That's a great question...
Remember the light spectrum I talked about earlier:
Remember that different wavelengths of light are measured in "nanometers"? A nanometer is a millionth of a meter.
Observe that the infrared part of the spectrum begins around 780 nanometers.
What you cannot see in that picture is that the infrared part of the spectrum ranges between 780 nanometers and 1 millimeter. To be precise, 1 millimeter equals 1,000,000 nanometers.
In reality, the infrared part of the spectrum thus ranges from 780 to 1,000,000 nanometers.
A big difference between red light therapy devices and sunlight is that the former only use the spectrum between 600 and 900 nanometers.
Sunlight, on the contrary, emits infrared light over and above 5,000+ nanometers
You might be thinking: "why exclusively use the 600 - 900 nanometer part of the spectrum, when sunlight includes many other infrared frequencies?"
That's a great question again!
There are two reasons why red light therapy devices only use the 600 - 900-nanometer wavelengths:
Red light therapy devices not causing a heat buildup in your body offers a big advantage. Why? Well, you can expose your body to massive amounts of the 600 - 900-nanometer wavelengths without causing overheating.
Let's explore that light between 600 and 900 nanometers:
To be more precise: not all wavelengths between 600 and 900 nanometers are equally beneficial.[340; 341]
Examples of very beneficial wavelengths are 625, 660, and 850 nanometers. Almost all (high-quality) red light therapy devices therefore exclusively use these very specific wavelengths.
If you use the 685 instead of the 660-nanometer wavelength, for example, you'll not gain the same health benefits.
Why is that important?
Let's consider what makes LED lights unique. LED lights are a breakthrough technology.
What do I mean?
One the one hand, LEDs do a lot of harm because they expose you to blue light after sunset. LED lights also have extreme benefits though: they can be made in such a way that they emit a very specific nanometer wavelength.
Stay with me...
You can buy LED lights that only emit 660 nanometer red light, for example, which will ensure that all light actually emitted lies between 650 and 670 nanometers.
That's a big advantage...
Traditional light bulbs do not have the capacity to emit just 625 or 850 nanometer light.
Two of my favorite traditional light bulbs - the incandescent and halogen light bulbs - have a continuous light output between 400 and 1,300+ nanometers. These traditional light bulbs are therefore less suited for red light therapy because they emit many different light frequencies.
Only since the invention of LED lights has it become possible to make panels that emit light only at a few very specific wavelengths - which have specific therapeutic value.
Traditional light bulbs have yet another problem though...
The careful reader might already have concluded that traditional light bulbs emit lots of heat. LED light panels do not emit much if any heat, especially if you're standing at a small distance from these panels.
Why does that matter?
If you were to use a traditional heat bulb, such as an incandescent bulb, you'll usually overheat before you've added sufficient amounts of the therapeutic light wavelengths to your body.
There's an alternative of course though: increasing your distance from the incandescent light bulb. But you'll find out later in this blog post why that might not be the optimal solution either. One drawback is that taking a long distance from a light will also decrease the light dosage that hits your skin and eyes.
Increasing the distance is thus not a perfect solution at all, because you'll spend a long, long time in front of that bulb.
And life is already passing by too quickly...
Let's get back to the red light therapy LED devices I just mentioned.
In terms of colors, red light therapy looks different than traditional light bulbs and the sun. The sun and some traditional light bulbs look yellow or orange-red. Red light therapy looks almost purely red.
The difference in look can be explained through the separate ways in which our eyes perceive the visible light.
Remember again that as a human being, you can only actually see the red part of red light therapy, as the infrared part of the light spectrum is invisible to the human eye.
All right. That's all you need to know about the definition of "red light therapy" and the basic physics. Let's now move on to the effect this light has in your body - physiology:
By understanding how red light therapy works in your body, I'm better able to explain all the benefits to you in the next section.
You might know by now that light is not there just to illuminate your environment so you can see. In previous articles, I've written extensively on how light influences the functioning of your body.
Examples are sunlight, which can increase your energy levels and well-being, or avoid exposing your eyes to bright light at night. If bright light enters your eyes after sunset, a hormone called "melatonin" is not secreted sufficiently, which inhibits your sleep (quality).
In other words, the light in your environment affects your health.
To be more precise, light actually penetrates into your body.
Fortunately, my good friend of mine actually helped me demonstrate how deep different wavelengths of light exactly venture into your body:
(If you cannot read the small font on that picture, you'll need red light therapy to fix your eyes. That's half-joking, to cover up for my poor photo-editing skills, but the statement also has some truth to it.)
Observe that some types of light penetrate deeper than others:[11-13]
Light thus penetrates into your skin, ending up in your blood vessels. By exposing part of your body to light, your blood can cause that light to also affect other parts of your body.
When light enters your skin, cells, and bloodstream, it affects the health of your body.
Light thus does a lot more than just allow you to see your environment.
It should not come as a surprise that light has this effect:
In fact, (almost) the entire food chain on the planet is dependent on light. Plants cannot survive without light, and animals cannot survive with plants.
And you cannot survive without animals (at least, not survive well).
Even though most people know that light influences plants, helping in the process of "photosynthesis", your human body thus has a similar process of photosynthesis as well.
Let's look at how red light therapy affects your health, once that light penetrates into your body:
(Infra)red light influences what are called "mitochondria".
Mitochondria are the "energy-producing factories" of your cells but are also relevant for cell defense. Red and infrared light therapy have a tremendous effect on your "mitochondria".
Look at this picture that schematically displays a human cell:
In that picture, number 9 signifies the mitochondria. While only two mitochondria are displayed here, in reality, one human cell contains hundreds and even thousands of mitochondria.
(As an interesting note, your mitochondria even have their own DNA.)
As you can see, the human cell has all kinds of different components, such as the center of the cell (number 2), and a layer that separates the cell from the outside world (number 14).
Don't worry too much about all these components in the human cell - I'm focusing exclusively on mitochondria.
Let's consider these mitochondria - as your cells' "energy factories" - in more detail.
Almost all energy in your body is created in your mitochondria. Without (properly functioning) mitochondria, you'd be dead almost instantly.
What kind of energy do mitochondria use? Mitochondria themselves are actually not using proteins, carbohydrates, and fats, but physics particles such as "electrons" and "protons", in relation to chemical elements such as "hydrogen".
Don't worry about these complex names.
The only thing that's important to remember is that the electrons and protons - in relation to chemicals in your cells - create energy in the form of "ATP". ATP stands for "Adenosine Tri-Phosphate" - a name you can also forget again.
Simply put, ATP is (often) considered the main fuel in your body.
(Advanced explanation: some highly regarded (but also highly controversial) scientists, such as Albert Szent-Györgyi, Gilbert Ling, and Gerald Pollack, have suggested through their work a very different conception of the primary role of ATP in the cell than the conventional model, an idea which is slowly garnering support among scientists. This idea involves ATP facilitating the flow of energy in biological tissues through its unique structure and molecular distribution of electric charge rather than acting solely as a simple carrier of chemical bond energy as "currency, "as is the current highly-simplified conception.[333-335])
You can see the details of a mitochondrion (singular) below:
That energy is mostly created through transferring these electrons and protons and chemicals from the intermembrane space (number 2) to the matrix (number 3.2), and vice versa.
Even though I'm oversimplifying here, oxygen that you've breathed and glucose (or fat) that you've eaten go into the cell, and water and carbon dioxide (CO2) comes out as end-products.
You know what's interesting?
You're reversing the process that happens in plants. Plants turn carbon dioxide and water into oxygen and glucose. Your mitochondria are turning that process on its head.
You might be thinking: "why are you telling me all this? I didn't come here for a biology course."
Okay, I get that. I'll get to the point:
It turns out some of the processes by which energy is created in your mitochondria are directly supported by red light therapy.[14-16; 18-20]
The end result of applying red light therapy is thus an increase in energy production.
Remember that almost all energy in your body is produced in your mitochondria. Red light therapy can thus increase your overall energy levels at the most basic cellular level, by stimulating your cell's energy factories.
Sounds great right?
Then, lastly, there's one more known mechanism by which red light therapy affects your physiology. This explanation is a bit more in-depth and advanced, but, nevertheless, extremely interesting:
(Advanced explanation: Besides mitochondria, there are other mechanisms by which red light therapy can increase energy in your body. One such mechanism is that infrared light can literally be stored in the water of your cells.[328; 329] Another mechanism is by removing excesses of a substance called "nitric oxide" from your mitochondria so that the mitochondria can process oxygen better.[330-332]
Let's explain that "water storage mechanism" for red light therapy in more detail. In essence, red and infrared light is charging your "human battery". To be more precise, the water in human batter is called "exclusion zone water", which is a phase of water that can be distinguished from solid, liquid, or a frozen state. That "exclusion zone", or "crystalline phase" of water can hold a charge.
Because red and infrared light build that exclusion zone, ultraviolet light can be stored in there as well.
Through the photoelectric effect in humans, (sun)light also programs electrons to transfer from their ground state to an excited state. After use in the mitochondria, electrons drop back to their ground state. Through this mechanism, ultraviolet light increase your energy levels.
Red light therapy and ultraviolet light thus work in conjunction. In nature, morning sunlight preconditions your cells to accept more ultraviolet light. With red light therapy, your ultraviolet uptake can also be enhanced--although to a lesser extent than through sunlight.
Biochemical reactions are not the most important thing that happens in a cell, but the acquisition dynamics of light are. Due to red and infrared light, electrons become better available and are more efficiently used in cytochrome C oxidase of the mitochondria.
Additionally, it is hypothesized that red light may alter the spin of protons in the mitochondria, thereby lowering inflammation levels. Protons are tied to inflammation, which are tied to (modern) disease.
What's one difference between LEDs and sunlight? Due to the flicker effect, melanopsin in our skin and eyes - which is intrinsically tied to our vitamin A cycle - might be negatively affected. In this specific sense too, red light therapy devices should only be used as a temporary replacement of sunlight.
Red light therapy thus merits an increase in vitamin A consumption - eggs, liver, and red meat are great vitamin A sources.
Lastly, beware: non-native electromagnetic frequencies or fluoride, on the contrary, destroy your cell's batteries to hold water - and thus your ability to hold charge in your cells. Less charge in your cells equals less health and performance.)
Is this all?
No! In the scientific literature, many more mechanisms are described. Nevertheless, I've aimed at describing the most important ones for now. Most people don't like complication.
And, if you're interested in learning more about these physiological mechanisms, you can still read the literature list below - included in this blog post.
That's everything you need to know about how red light therapy affects your body's physiology! Want to learn more?
Read this very in-depth Everything You Need To Know About Red Light Therapy blog post by Alex that ventures into many related topics regarding red light! Also, you can read more about the 36 Powerful Benefits Of Red Light Therapy HERE.
Next up, a shot treatment of a topic many people have been inquiring into as well - whether red light therapy has potential side-effects. Here we go:
But how about red light therapy side-effects?
Looking at all of the science, there are all five (potential) side effects:
What's even more important, is that there is no known interference of red light therapy with prescription medication that I've come across.
Overall, the safety profile of red light therapy is thus very good. You can safely affect your body's physiology!
All the basics you need to know about how red light therapy works. Let's conclude:
Hope you loved this blog post!
I very much hope that you envision red light therapy to be a game-changer for human health and humanity.
For hundreds of years now, we've mostly spent our time indoors. Red light therapy is giving huge benefits for people who stay indoors most of the time - and perhaps even for sun-lovers like me!
In essence, red light therapy allows you to better control your light exposure - that's a huge benefit! Every single incremental habit you add to your routine counts, and this is one of the big ones.
Learn more? Sure! Read Everything You Need To Know About Red Light Therapy written by Alex and you'll be a few steps ahead of the game!
This is a post by Bart Wolbers. Bart finished degrees in Physical Therapy (B), Philosophy (BA and MA), Philosophy of Science and Technology (MS - Cum Laude), and Clinical Health Science (MS), and is currently a health consultant at Alexfergus.com.
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