Please don’t use red light therapy, at least not until you read and understand this article.
The reason we didn’t stumble onto red light therapy when lightbulbs were invented is simple. The therapy works when you have the right amount of energy from the correct wavelength. If you do red light therapy incorrectly, you will not get the right amount of energy. It’s not going to work.
Rather than disappointing yourself, just don’t buy red light therapy unless you plan to follow the instructions with your device!
Red Light Therapy Transfer Energy to Cells
We make energy from food, but we also make energy from light. That’s why we have more vitamin D after being in the sun. While vitamin D depends on ultraviolet rays, energy metabolism relies on infrared rays. With the right amount of energy our bodies control our pain, fix our skin, and reboot our brains.
Inside every cell are thousands of energy hubs called mitochondria. The hubs contain battery factories called the electron transport chain and ATP Synthase. Red light therapy absorbs in the electron transport chain. The photons lend energy to the mitochondria through Einstein’s photoelectric effect. The result is more metabolic energy to run this thing we call a body.
RPM and Speed
There’s a definite limit to how much light the iron and copper inside the proteins can absorb. So leaving the light on for too long, or holding it too close, can overpower the photoreceptors, making the therapy useless.
The first rule of proper red light therapy is to obey the treatment time schedule. Every second of light exposure adds more photons to the electric transport chain. There will come a point when the iron and copper embedded in the proteins can’t take any more energy. If you keep exposing them to more light, they will reject the light and reverse the gains.
The amount of time for each session is completely dependent on your device. It doesn’t depend on the device’s wattage, which is its input power.
For example, you could use a light rated at 50 milliwatts per square centimeter per second (50 mW/cm^2). That power density works out to 3 joules per minute exposure. You generally want to stay between 5 and 100 joules per session.
So what would happen if you used the light for 20 minutes? 60 joules, that’s well within the range (3 joules x 20 minutes = 60 joules).
If you used it for two hours? 120 minutes times 3 joules is 360 joules. While there are some studies using that much light, they’re outside the majority.
Energy has a way of dropping off dramatically with distance. This is reflected in the inverse square rule that says that energy drops fast with distance. The law is: Intensity is equal to the inverse square of the distance from the source.
You don’t need to know the law’s vocabulary to obey it. If the manufacturer says to put the light at 6 inches from the target, use a ruler to measure six inches from the target. Because four inches gives you a lot more energy, and 10 inches gives you a lot less.
Here’s an easy way to picture the inverse square law. If you hold a lamp up to your abdomen, right on the skin, how much light spreads out past your body? Now put that light on the table, and aim it at your abdomen. Now how much light spreads out past your body? Finally, walk a foot backward from that lamp, and look at the light on your abdomen getting fainter. More light is spreading out to either side of you, and therefore not onto you.
So that’s all the inverse square law is. The more the light spreads out, the less light hits your target.
The “Official” Irradiance Problems
Too many manufacturers are jumping into the red light therapy market without a clue what “irradiance” means. They use solar meters to measure a lamp’s output when solar meters don’t measure LEDs very well.
There are two ways to resolve this problem when you’re shopping for red light therapy. You can avoid manufacturers that don’t prove their light’s specifications. Just don’t buy from them. Or you can assume that the actual irradiance is about half of what they claim.
The easiest path here is to buy from manufacturers you trust. Yes, Alibaba is cheaper (and carries little in the way of guarantees, by the way). But are you getting the right wavelength of light, with instructions for the correct distance and time per session?
This is why I don’t want you to buy red light therapy until you understand the dosing problem. If you do it wrong, it won’t work. Red light therapy is a powerful pain killer, it helps foggy brains come back online, and it powers movement and exercise. I want everyone to use red light therapy correctly so that everyone can experience its benefits.