Definition 

 Photobiomodulation (PBM) is a light therapy that uses non-damaging forms of light, including lasers, LEDs, and broadband light, in the visible and invisible spectrum. It is a non-heating process involving specific body tissues reacting to the light physically and chemically, resulting in beneficial therapeutic effects. 

 

The process explained

 The light used in PBM is within the visible and near-infrared spectrum and is measured in nanometers (nm). The most common wavelengths of light used in this therapy are in the red-light spectrum (620nm to 750nm) and near-infrared (750nm to 2500nm). Within these light ranges, specific tissues, cells and biochemicals can absorb the light as a photon (particle of light) and then change their function. For example, the substance in the blood called haemoglobin transports oxygen and absorbs the wavelengths of light at 400-600nm (blue/green/yellow light). 

 The main structures in the body that PBM wants to interact with, in other words, the photon of light to be absorbed by, are calcium channels and cytochrome C oxidase (CCO). These cell components are an essential part of our cell's metabolism. The wavelength of light that they preferentially absorb is 620-660nm (red light) and 800-900nm (near-infrared light). 

 

Mitochondria 

 Mitochondria are tiny structures within cells that produce energy as ATP, the fuel of life. Within the mitochondria is an enzyme called cytochrome C oxidase (CCO). CCO is a crucial enzyme in the processing of oxygen that produces energy in the form of ATP. So, when light absorbs into the cell and then interacts with the mitochondria, it removes Nitric Oxide from this enzyme to allow more ATP to be produced. This process also triggers an increase in membrane potential; thus, cellular function increases. 

 Due to the release from CCO, a substance called Nitric Oxide (NO) is elevated. NO has many functions within the body, but one of its primary tasks is enhancing circulation by widening blood and lymphatic vessels. 

 Reactive oxygen species (ROS) increase when we process more oxygen within the mitochondria. Commonly known as free radicals, these compounds can be highly harmful. However, when briefly increased by PBM, they stimulate many protective mechanisms that help the cell protect itself. This process is similar to some of the benefits of exercise. Interestingly, if ROS is high within the cells, the increase in ATP via PBM induces means to lower these compounds, a modulation effect. 

Calcium Channels

 As part of our cells' structure, we have gated channels that allow substances in and out. Calcium channels are stimulated by PBM, changing the calcium concentration in and outside the cells. This process has been shown to increase some cells' activity, increase the growth of cells, reduce pain signals, regulate muscle function and affect neurotransmitter release (chemicals that can affect the brain). Calcium channels are an area of PBM that requires more study but are linked to the benefits of pain, inflammation, injury healing and exercise performance. 

 This process also increases cyclic AMP or cAMP, a molecule with many functions in the body. The increase is associated with reducing inflammation and regulating energy stores (body fat, blood sugar, etc.).

 

Specific benefits 

 These are the two main fundamental mechanisms currently known to explain the immensely positive effects of PBM. To put this into the further context of how it can benefit the human body:

 · Increased exercise performance and recovery via elevated muscle strength, energy availability, prevention and repair of muscle damage (Ailioaie & Litscher, 2021).

 · Facilitates wound healing, reducing inflammation in the skin, promoting collagen production and reducing scar tissue formation (Mosca et al., 2022).

 · Reduced pain, swelling and lymphedema in post-surgery contexts such as breast cancer surgery, tooth extractions, sprains and other injuries. Equating to improved recovery times and quality of life (Saravana Priyan Soundappan, 2013)(Ezzati et al., 2019).

 · Regrowth of hair in male and female hair loss induced by hormones or chemotherapy (Hamblin, 2019).

 · Reduced pain and increased function of joints/tendons in arthritis and injury (Akamatsu et al., 2021). That delayed the need for surgery such as knee replacement (Giolo et al., 2022).

 · Reduction in presentations of acne, psoriasis and herpes simplex/cold sores (Diogo et al., 2021)(Zhang & Wu, 2018). 

  · Sunburn heals faster, and skin has better protection against UV damage (Mosca et al., 2022) .

 · Reduction in nasal discharge, congestion, fatigue and facial pain in sinusitis (Williams et al., 2022). 

 · Elevation in thyroid hormone production, reduction in medication use and thyroid autoantibodies in Hashimoto's thyroiditis (Berisha-Muharremi et al., 2023). 

 

 Many parameters are adjusted to get the specific effects in human tissue, such as wavelength of light and the amount of joules/energy of light applied in each treatment. So, it is always advised to get professional advice to get the most out of photobiomodulation light therapies. 

 

 

Ailioaie, L. M., & Litscher, G. (2021). Photobiomodulation and Sports: Results of a Narrative Review. In Life(Vol. 11, Issue 12). https://doi.org/10.3390/life11121339

Akamatsu, F. E., Teodoro, W. R., Itezerote, A. M., da Silveira, L. K. R., Saleh, S., Martinez, C. A. R., Ribeiro, M. L., Pereira, J. A., Hojaij, F., Andrade, M., & Jacomo, A. L. (2021). Photobiomodulation therapy increases collagen ii after tendon experimental injury. Histology and Histopathology36(6), 663–674. https://doi.org/10.14670/HH-18-330

Berisha-Muharremi, V., Tahirbegolli, B., Phypers, R., & Hanna, R. (2023). Efficacy of Combined Photobiomodulation Therapy with Supplements versus Supplements alone in Restoring Thyroid Gland Homeostasis in Hashimoto Thyroiditis: A Clinical Feasibility Parallel Trial with 6-Months Follow-Up. Journal of Personalized Medicine13(8). https://doi.org/10.3390/jpm13081274

Diogo, M. L. G., Campos, T. M., Fonseca, E. S. R., Pavani, C., Horliana, A. C. R. T., Fernandes, K. P. S., Bussadori, S. K., Fantin, F. G. M. M., Leite, D. P. V., Yamamoto, Â. T. A., Navarro, R. S., & Motta, L. J. (2021). Effect of blue light on acne vulgaris: A systematic review. Sensors21(20), 1–13. https://doi.org/10.3390/s21206943

Ezzati, K., Fekrazad, R., & Raoufi, Z. (2019). The effects of photobiomodulation therapy on post-surgical pain. Journal of Lasers in Medical Sciences10(2), 79–85. https://doi.org/10.15171/jlms.2019.13

Giolo, F. P., Santos, G. S., Pacheco, V. F., Huber, S. C., Malange, K. F., Rodrigues, B. L., Bassora, F., Mosaner, T., Azzini, G., Ribeiro, L. L., Parada, C. A., & Lana, J. F. S. D. (2022). Photobiomodulation therapy for osteoarthritis: Mechanisms of action. World Journal of Translational Medicine10(3), 29–42. https://doi.org/10.5528/wjtm.v10.i3.29

Hamblin, M. R. (2019). Photobiomodulation for the management of alopecia: Mechanisms of action, patient selection and perspectives. Clinical, Cosmetic and Investigational Dermatology12, 669–678. https://doi.org/10.2147/CCID.S184979

Mosca, R. C., Santos, S. N., Nogueira, G. E. C., Pereira, D. L., Costa, F. C., Pereira, J. X., Zeituni, C. A., & Arany, P. R. (2022). The Efficacy of Photobiomodulation Therapy in Improving Tissue Resilience and Healing of Radiation Skin Damage. Photonics9(1). https://doi.org/10.3390/photonics9010010

Saravana Priyan Soundappan, M. C. C. S. V. V. R. S. J. S. S. A. P. (2013). of Dental Sciences. Indian Journal of Dental Sciences.5(3), 24–25. https://doi.org/10.4103/IJDS.IJDS

Williams, R. K., Raimondo, J., Cahn, D., Williams, A., & Schell, D. (2022). Whole-organ transdermal photobiomodulation (PBM) of COVID-19: A 50-patient case study. Journal of Biophotonics15(2), 1–12. https://doi.org/10.1002/jbio.202100194

Zhang, P., & Wu, M. X. (2018). A clinical review of phototherapy for psoriasis. Lasers in Medical Science33(1), 173–180. https://doi.org/10.1007/s10103-017-2360-1