Photobiomodulation (PBM) is a therapeutic method using specific wavelengths of light to interact with the body’s cells. This interaction is not based on heat; instead, cells absorb light energy and convert it into chemical energy, a process similar to photosynthesis in plants. Light from sources like lasers or light-emitting diodes (LEDs) stimulates natural biological processes, using non-ionizing red and near-infrared light to engage with cellular components and support their function.
The Science of Photobiomodulation
The biological effects of PBM begin inside the mitochondria, the structures that produce most of the cell’s adenosine triphosphate (ATP), its energy currency. During a PBM session, light particles (photons) are absorbed by a protein in the mitochondria called cytochrome c oxidase. This protein is a component of the electron transport chain, the process that generates ATP.
When cells are stressed by injury or disease, they produce excess nitric oxide, which binds to cytochrome c oxidase and displaces oxygen. This action hinders the mitochondria’s ability to produce ATP efficiently, leading to oxidative stress and inflammation. PBM uses light energy to break the bond between nitric oxide and cytochrome c oxidase, allowing oxygen to rebind.
This restoration of oxygen brings ATP production back to normal levels and reduces oxidative stress. With improved energy metabolism, the cell functions more effectively, supporting tissue repair and reducing inflammation. The process also modulates reactive oxygen species (ROS), which can act as signaling molecules to activate pathways for cellular repair. This cascade of events drives the therapeutic outcomes of PBM.
Types of Photobiomodulation Devices
PBM therapy is delivered through a variety of devices, each designed to suit different needs and treatment areas, from broad coverage to highly targeted treatments. These devices can be found in professional clinical settings and are also available as at-home units for regular use.
- Large, flat panels equipped with LEDs treat extensive areas like the back or legs, addressing widespread muscle soreness or skin conditions.
- Masks and wands offer focused application, with masks shaped for facial skin rejuvenation and wands providing precision for small joints or specific spots.
- Wearable wraps and belts provide a flexible solution for contoured parts of the body like a knee, elbow, or the lower back.
- Helmets and caps are designed for the scalp to stimulate hair follicles and address hair loss.
- Full-body beds, found in clinics, envelop the entire body in light for systemic benefits like overall inflammation reduction or enhanced athletic recovery.
Common Applications and Uses
A primary application for PBM is managing pain and inflammation. It is applied to conditions like joint pain from arthritis, soft tissue injuries such as sprains and strains, and chronic pain disorders. The therapy can lead to pain relief and accelerated healing of injured tissues.
For skin health and aesthetics, PBM is used to promote rejuvenation. Specific wavelengths of red light stimulate the production of collagen and elastin, proteins that give skin its structure. This can result in the reduction of fine lines and wrinkles, and it is also applied to treat acne and improve overall skin tone.
Athletes and fitness enthusiasts use PBM for performance enhancement and muscle recovery. Treatments before or after strenuous exercise can reduce delayed onset muscle soreness (DOMS) and shorten recovery times. By supporting cellular repair, the therapy helps muscles recover more efficiently after exertion.
Another application is treating hair loss, specifically androgenetic alopecia, a common form of hair loss. PBM devices like helmets or caps are used to stimulate hair follicles, encouraging them to enter the growth phase. This can potentially increase hair density and thickness over time.
Key Device Specifications and Safety
Several technical specifications determine a device’s effectiveness. Wavelength, measured in nanometers (nm), is a primary factor as it dictates penetration depth. Red light, in the 630-660 nm range, is absorbed more superficially and is used for skin health, while near-infrared (NIR) light, in the 810-850 nm range, penetrates deeper into tissues, making it suitable for treating muscles and joints.
Irradiance, or power density, is another parameter describing the concentration of light energy delivered to the treatment area. Measured in milliwatts per square centimeter (mW/cm²), it indicates the light’s strength. A higher irradiance delivers more energy in less time, which can influence treatment duration.
The total energy delivered during a session is known as the dosage, which is a function of both irradiance and time. Achieving the correct dosage is important for therapeutic success. There is a biphasic dose response, meaning too little or too much light can be ineffective or even counterproductive.
Safety is an important consideration when using PBM devices. It is recommended to use eye protection, especially when using devices near the face, as the eyes are sensitive to bright light. It is also useful to understand the distinction between devices cleared by regulatory bodies like the FDA and those sold as general wellness products. Following the manufacturer’s instructions for treatment times and distances is necessary for both safety and efficacy.