The human body uses light-induced photochemical reactions on a daily basis. From the photosensitive cells in our eyes to the light-reliant vitamin D synthesis process in our skin, our bodies rely on and can use light in numerous ways. It stands to reason, then, that many cells in the human body may react to light. So how does light affect cells in the body, and how can it be used for the benefit of human health? That is the question behind the treatment method known as low-level laser therapy or photobiomodulation.
Low-level laser therapy is known by several names. Most commonly, it is known as photobiomodulation therapy, low-power laser therapy, cold laser therapy or simply by the acronyms LLLT or PBMT.
Low-level laser therapy is a term that describes the therapeutic application of light to the body. First developed in 1967 by Endre Mester in Hungary, low-level laser therapy involves placing a light source near to or on the skin, allowing the photons to move through the tissue and interact with cells in the body. Mester first developed this method after finding that it improved hair growth and stimulated wound healing in mice. Shortly after his initial development of the treatment method, Mester explored the therapy’s ability to aid in the healing of skin ulcers in 1972.
Low-level laser treatment doesn’t involve the use of the high-powered lasers that most people are familiar with. Instead, low-level lasers, LEDs and broadband lights are used to emit red and near infra-red light with wavelengths of 632 nm to 1064 nm at 1 to 1000 mW. These low-power light sources do not generate heat, so they do not burn the skin during the therapeutic process.
Since the development of the process, the benefits of applying laser therapy treatments have been explored at length. The photochemical changes that occur in cells as a reaction to the application of light can help accelerate wound healing and tissue regeneration, increase circulation, reduce inflammation and even help manage pain.
While the benefits of photobiomodulation have been observed in medical studies, the mechanisms that lead to these results are still being studied. Though we still have plenty to learn about the effects of light energy on different types of cells, the general consensus is that light therapy works primarily by affecting the mitochondria inside human cells.
The primary idea behind photobiology is that when light hits certain molecules, called chromophores, the energy of the photon causes electrons in those molecules to be excited and jump into higher-energy orbits, effectively storing energy within the molecule. The mitochondria of the cell are thought to contain such chromophores, allowing them to store more energy to be used in the biochemical processes that mitochondria complete. Mitochondria then use this energy to increase the production of essential substances in the body. The most important of these are the following:
Several other mechanisms are likely improved through the use of laser therapy. For example, NO improves the production of cyclic guanine monophosphate, which is involved in other signaling pathways in the body. Laser therapy also improves the synthesis of DNA and RNA, which in turn promotes the production of proteins and growth factors in the body.
The biological processes promoted by laser therapy result in various health benefits to users, each of which has been studied at length. A few of the benefits of laser therapy are discussed in detail below:
Pain is the most common reason that people see doctors in the United States, with one in three Americans affected by chronic pain each year. Low-level laser treatment has been explored in various studies as a method of decreasing several types of pain, including the following:
Laser therapy treatment has also been effective in managing pain for athletes recovering from training or injuries It is thought that the reason low-level laser therapy is so effective is that it stimulates the nerve endings of nociceptors, or pain receptors, that lie close to the skin.
Laser therapy treatment has been widely regarded as an effective way to manage and reduce inflammation in a variety of applications. Athletic programs commonly use low-light laser therapy to help reduce inflammation and promote muscle recovery for training or injured athletes. Additionally, medical practices have used laser therapy as a way to manage inflammation for patients recovering from various injuries. One study showed that low-level light therapy effectively reduced post-surgery inflammation for patients recovering from total hip arthroplasty surgeries.
The primary mechanism by which light therapy helps reduce inflammation is vasodilation. In vasodilation, small arteries and lymph vessels increase in size, allowing inflammation, swelling and edema to move away from injury sites. Not only does this mechanism reduce inflammation, but it also improves the healing process overall.
Though low-level laser treatment is a relatively new field of medicine, the results speak for themselves. As the studies previously mentioned mentioned show, patients recovering from injuries, surgeries and more can expect excellent results from low-level laser therapy, and people looking to improve their hair, skin and pain outcomes already have options available to them.
It is important to note, however, that low-level laser treatments may not be the best option for everyone. Pregnant women, for example, are not recommended to pursue laser therapy treatments since the effects on fetuses are not well understood. Results may also vary per person — the number of treatments needed may vary depending on the condition, the severity of this condition and the patient’s response to treatment.
Despite it being a relatively new field of study, cold lasers are still being studied at length for their potential benefits. Laser therapy applications are currently being studied for use against viruses, scars, burns, wound healing and much more.