Is all light therapy the same? Light has a wide range of health benefits — natural sunlight boosts the body’s vitamin D production, for example. Light is beneficial because specific wavelengths of light can be used for treating specific applications. Medical experts have created devices that emit particular wavelengths of light that improve health and wellness in a process known as photobiomodulation (PBM) therapy.
What Is Photobiomodulation?
PBM therapy, sometimes known as PBMT, is an umbrella term that covers several technologies that use various wavelengths of light for therapeutic purposes. These technologies include LASERS and LEDs that emit different wavelengths of light in the visible and near-infrared spectrum. Many people use the terms red light therapy and photobiomodulation interchangeably, but red light is a type of PBM therapy.
About wavelengths in PBM therapy
The term light, electromagnetic waves, and radiation all refer to the same physical phenomenon: electromagnetic energy. This energy can be described by frequency, wavelength, or energy. Light travels in waves with a peak at the top and a valley at the bottom. Scientists often discuss light in terms of its wavelength, which is the length of a wave from one peak to the next. They measure wavelength in nanometers (nm). Visible light, which you can see, measures 400 to 700 nm. Ultraviolet light has shorter wavelengths, measuring 10 nm to 400 nm, and infrared light has longer wavelengths that measure 700 nm to 1 mm.
The wavelength determines the color and if it can be seen with the naked eye. Light with a wavelength of 650 nm to 700 nm appears red, for example, while light with a wavelength of 450 nm looks blue.
Different wavelengths of light also cause various effects in the human body. Photobiomodulation is now customizable to fit nearly every need. Aspen Laser’s PBM therapy systems, for example, use one or more wavelengths of light.
Power is also important when discussing the various types of photobiomodulation therapy systems. Higher power, when combined with longer wavelengths, allows the light to penetrate deeper into the body than lower power short wavelengths. The FDA classifies laser devices according to their power and in terms of milliwatts (mW) and watts (W). For example, Class III laser light provides a power output between 5 and 500 mW, and Class IV laser light produces light above 500 mW.
Types of Photobiomodulation and Their Differences
There are two main types of PBM therapy: laser and LED.
Laser
LASER is an acronym for Light Amplification by Stimulated Emission of Radiation.
Laser light wavelengths include a range from 500 nm to 1100 nm. Scientists describe this range as the “biological window,” which means the light can penetrate through the skin and enter the cells to affect tissue. The depth of penetration varies depending on the specific wavelength and a number of factors including power level, operating mode and treatment beam size. Wavelengths measuring 600 to 700 nm effectively treat superficial tissue, while the longer wavelengths of 780 to 1100 nm penetrate further to treat deeper tissue.
Deep Tissue Laser Therapy
Photobiomodulation has been found to be most effective when using high power or high intensity therapy lasers. Deep tissue laser therapy, otherwise known as High Intensity Laser Therapy (HILT), can provide sufficient dosage levels that are required to generate a positive clinical outcome. These lasers are classified by the FDA as Class IV lasers and are significantly more powerful and different than Class III lasers, often called Low Level Therapy Lasers (LLT) or cold lasers. Many conditions, for example low back pain, require the laser energy to penetrate deep into the muscle tissue and with enough energy (dosage), to stimulate a healing response in the damaged and unhealthy cells. Class IV lasers are able to provide this response in a short amount of time, speeding up healing and cell regeneration typically in a 10 minute treatment session. In contrast, Class III therapy lasers are unable to provide the required energy and penetration, resulting in nominal or no positive outcome.
LED
LED is an acronym for Light-Emitting Diode. LEDs differ from lasers, by providing light that is non – coherent (non – focused) and scatters in different directions. LED from therapeutic sources has 590, 633, 830 nm, and 940 nm wavelengths. The advantages of LED PBMT is that it can be administered in either an unattended treatment in a healthcare practice or self – administered in a home or private setting. LED treatment times are longer than laser therapy treatment times, and outcomes may be longer to take effect.
Red Light Therapy
Historically, red light therapy was used in Dermatology medical practices for treating the skin including acne and a variety of skin lesions. Red light therapy uses light wavelengths measuring 600 nm – 700 nm (short wavelengths) that penetrate human tissue superficially, with most of the energy absorbed in the first 2 centimeters (CM) of the tissue. Dermatological conditions do not require depth of penetration to be effective. For conditions requiring penetration deeper than the skin (musculoskeletal), Near-infrared (NIR) wavelengths (700 nm – 1100 nm) must be used.
Red light therapy typically uses LEDs to deliver PBMT and is most effective when combining red LED with NIR LED. Treatment can be provided in two ways: full body treatment or targeted therapy. Full-body red light therapy exposes the entire body to red light using an LED bed. Targeted red light therapy is delivered using a handheld device or panel that allows the provider to focus on a specific area of the body.
Photobiomodulation therapy (PBMT) is gaining popularity among doctors (MD, DO), chiropractors, physical therapists, sports medicine professionals, athletic trainers, podiatrists, and veterinarians. However, many red light therapy companies and products are making misleading and inaccurate claims regarding what their product can treat and the expected results. A large number of these products have not been tested or cleared by the FDA for specific medical indications for use or clearances. For example, treating acne or skin lesions requires FDA 510k clearances for a product to make this claim or market. Statements regarding depth of penetration and dosage levels that are found with lasers, are being falsely attributed to red light LED products.
PBMT holds tremendous promise in medicine and wellness for drug free pain relief, decreased inflammation and accelerated healing; but must be administered with products providing optimal dosages and penetration that are determined by using correct (multiple) wavelengths, correct power levels (high) and correct operating modes (continuous wave and pulsing).
