The significance of light for physical and emotional health was well known in all cultures. The Rig Veda Samhita (about 1200 bc), describes the significance of light for everything that lives. The famous Greek physician Hippocrates (460-377 bc) used to treat skin and other diseases with sunlight.
Today low-level laser therapy is no doubt one of the gentlest of all light therapies. When applied correctly, the light energies that are employed are lower than those in all above-mentioned phototherapeutic methods.
A person who is sunbathing receives about 1000 joules per minute spread over his or her entire body. However, the precise Light energy of 3joules hitting the surface of the skin through infrared light, is sufficient to stimulate most acupuncture points. So, low-level laser therapy works with small light stimuli. The only reason they can have major therapeutic effects is that they trigger enhancement effects in the body and concentrate more light on, say, one acupuncture point compared to the surrounding area. In other words, the crucial impact factor in low-level laser therapy is not the radiation dose but the precisely directed communication with essential control centers for processes that take place within the body.
Today we know that the enhancement effects due to the absorption of laser light are achieved on the subcellular level. The primary mechanisms of low-level laser therapy are based on interactions between the photons and molecules in the intracellular space. Therapy lasers (when applied properly) transmit very low energy densities, which however are sufficient for this photo-bio-stimulation.
The secondary effects describe the biochemical changes of the metabolism and their manifestations at the tissue level which are induced by the primary mechanisms.
The primary effects of low-level laser therapy at the cellular level are attributed to the absorption of monochromatic near-infrared radiation by components of the respiratory chain. It causes an improvement of the electrochemical potential of protons, an increase in ATP, RNA and protein synthesis, and a boost in oxygen consumption, the membrane potential, and NADH synthesis.
The activation of the cellular metabolism is the direct, primary, and decisive effect of photo-stimulation with a low-level laser. At the tissue level, this process translates into the effects which we associate with low-level laser therapy. It is these effects that made the technique famous. They are often summarized as the following five essential principles: