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What is Photobiomodulation?
“Photo” means light.
“Bio” means life.
“Modulation” means a change in something.
So photobiomodulation is the use of light to cause a change in man or animal life.
Photobiomodulation is a new name for light therapy. In fact, the term photobiomodulation marks the acceptance of light therapy into the practice of western conventional medicine. It’s a big deal.
The Formal Definition of Photobiomodulation
NAALT defines Photobiomodulation Therapy as “A form of light therapy that utilizes non-ionizing forms of light sources, including LASERS, LEDs, and broad-band light, in the visible and infrared spectrum. It is a non-thermal process involving endogenous chromophores eliciting photophysical (i.e. linear and non-linear) and photochemical events at various biological scales. This process results in beneficial therapeutic outcomes including but not limited to the alleviation of pain or inflammation, immunomodulation, and promotion of wound healing and tissue regeneration.”
The Interpretation of the Formal Definition of Photobiomodulation
Photobiomodulation is a form of light therapy.
It uses harmless forms of light sources such as low level lasers, LEDs and broad-band light sources including incandescent, fluorescent or halogen lights.
It does not work by heat.
It works because our cells contain “chromophores” which literally absorb light.
Once the light is absorbed, it sets off a complex group of physical and chemical reactions within the cell. These reactions can and do extend to cells that have not even been exposed to the light.
All the effects of this process have so far been positive and beneficial.
Just a few of the beneficial effects include:
- alleviation of pain
- alleviation of inflammation
- stimulating the immune system
- wound healing
- tissue regeneration
Red Light Therapy and Photobiomodulation
Red light therapy is a large part of the science of photobiomodulation. It uses visible red wavelengths roughly between 620 nm and 700 nm.
The modern science of photobiomodulation was actually discovered using a red laser.
Near Infrared Light Therapy and Photobiomodulation
Laser or LED?
The modern discovery of this science was made with a laser. At first it was thought the laser was causing the effect, and so the next 20 years of research was done with lasers only.
Then it came to be understood that it was the light having the effect, not the laser.
Since then, LEDs have replaced lasers for most photobiomodulation therapy (PBMT).
In fact, PMBT can be done with any type of light source including incandescent, fluorescent, halogen, LED, or low power laser. LEDs have certain advantages including affordability, safety, durability, energy efficiency and low to no heat transmission.
Wavelength (nm)
One of the first numbers you are going to come across is something like this: 660 nm.
What does the nm mean?
nm is short for “nanometer.” (A nanometer is one billionth of a meter.)
One way that light travels is in waves, like sound. The wavelengths of light are measured in nanometers. The number before the nm denotes the color of the light as it moves through the spectrum.
Violet Light – 380-450 nm
Blue Light – 450-495 nm
Green Light – 495-570 nm
Yellow Light – 570-590 nm
Orange Light – 590-620 nm
Red Light – 620-750 nm
(non visible) Infrared energy – 750 nm – 1200 nm
So if you see the number 660 nm, that simply means red light. 630 nm is also red, but it would appear more on the orange side of red.
A lot of photobiomodulation therapy (PBMT) uses near near infrared light, which comes just after red on the spectrum, but it is invisible. Most common near infrared wavelengths used are 810, 830 and 850 nm.
What Kind of Power Does it Take?
Not much.
Just like it’s not the laser that makes this therapy work, it’s not the power that makes it work, either. It’s mostly the wavelength, or color of the light.
Of course, you need enough power to start the reaction, but that’s as low as 1mW/cm2 – it’s safe to say that every light therapy device on the market is plenty powerful enough to be effective.
In-home devices usually range from about 10-25 mW/cm2. Some medical devices use around 50mW/cm2 – not because more power is more effective though, but more power means a shorter treatment time.
More power output also means more light reaches the target depth – this can be more beneficial for deeper targets like large muscles, joints, bones and organs.
The Dose is the Important Thing
There is a window where photobiomodulation is most effective. This window will be different depending on the wavelength, power output, and specific condition you are treating.
The most discussion surrounding dose is with red and near infrared light therapy. A dose that is too small will have no effect, and a dose that is too large will have no effect.
How do you find and stay in this window? Simply follow the directions that come with your device, and resist the inclination to think that “more is better.” If the device says 5 minutes, use it for 5 minutes, not 20 minutes.
