What is it?
Photobiomodulation (PBM) was discovered in 1967 by Endre Mester from Hungary in attempt to repeat an experiment that had been recently published in Boston, USA (1) destroying a cancerous tumor experimentally implanted in a rat (2). Although the laser used was only a fraction of the power of the original laser used in Boston, efforts were not lost. Instead of curing the experimental tumors with his low-powered laser, he instead succeeded in stimulating the regrowth of hair and the healing the implant wound, leading to what we now know as “low level laser therapy” (LLLT) (3,4) and subsequently PBM (5).
PBM involves the utilization of light from the visible and (invisible) near infrared portions of the light spectrum. Due to the relatively low power density used in Low Level Light Therapy (LLLT), LLLT therapy is not painful, thermal (involving heat) or injurious to patients in any way (6). Specific characteristics of a light source, such as, wavelength, power, coherence, and pulse schedule are modifiable and are determined based on the intended goals for each patient (7-17).
Why is it important?
Benefits of PBM have been researched to be both on a cellular and systemic level (1-6). Cellularly, photons emitted from the light source facilitate the production of Adenosine Triphosphate (ATP), the energy of the cell, by disassociating a chemical called Nitric Oxide (NO). NO, when not disassociated, particularly in hypoxic and damaged cells, inhibits enzymes needed for ATP production, thus promoting instability the mitochondria, oxygen utilization, glucose metabolism and ultimately ATP production. In addition to ATP production, PBM opens special light-mediated cellular channels (18) involved in temperature regulation, and initiates mitochondrial signaling pathways resulting in cellular protective, antioxidant, and anti-apoptotic (health) effects in cells (19).
While cellular activities are the foundation of overall body function, there are also systemic (full body) effects of PBM. In addition to allowing for the increase in ATP production and molecular neuroprotection, NO, when dissociated, signals pathways involved in increasing blood flow in the body, improving circulation, production and activation of stem cells, and anti-inflammatory effect, leading to improved function of the target tissue and ultimately improved cerebral oxygenation (20,21).
How does it work?
PBM therapy may be used on any area of the body, but as mentioned before, will need to be customized, based on the target tissue, by paying particular attention to the various settings (22-24). When placed over certain areas of the head (transcranial PBM), studies have demonstrated that the energy (photons) can penetrate up to 50 mm (2 inches) into specific areas of the brain (32)! Neural pathways can be targeted allowing the photons present in the light source to penetrate the skull, and as mentioned earlier, stimulate chemical changes within cells and initiate biological reactions, including, but not limited to, improvement in metabolism, blood flow, neurogenesis, and decrease in inflammation and oxidative stress (4,6).
How does it help?
Although PBM was primarily studied for the stimulation of wound healing and reduction of pain and inflammation in various orthopedic conditions such as tendinitis, neck pain, and carpal tunnel syndrome (4), over the past 50 years since its discovery, and extensive research in the effect it has on the cellular and systemic level, PBM has come into use for treatment of pain (25) wound healing (26) cosmetic purposes, such as decreasing the severity of wrinkles, (4) re-growing hair (27), stroke and even neurological conditions (28-31) associated with deficits or imbalances in cellular function or blood regulation including, major depressive disorder (30), Traumatic Brain Injury (TBI), Alzheimer’s Disease (28,29,31), Parkinson’s Disease, stroke (28), and cognitive decline.