Research Studies

The Scientific Evidence: Light Therapy Clinical Research & Results

Low-level polychromatic light therapy (PLT) is a leading-edge medical treatment that has steadily grown in functionality and popularity since its discovery in the 1960’s. Medical doctors, chiropractors, researchers, and other licensed healthcare practitioners utilize PLT to reduce pain, promote wound healing, and support improved quality of life for people across the globe. Clinical studies and personal experiences reveal amazing health-promoting and -restoring benefits without the use of drugs, surgeries, or invasive treatments.

In 2016, the National Institute of Health database adopted the word photobiomodulation (PBM) as the new medical science heading (MeSH) keyword for the science of light therapy and its technology. They felt photobiomodulation more accurately describes the physiological mechanism(s) that result from the application of FDA-cleared light technology. You’ll find over 5000+ research articles about photobiomodulation and its technology on the PubMed website (www.pubmed.gov). Use one of the following keywords in your search: photobiomodulation, LLLT (low level light therapy), or polychromatic light therapy to learn more.

Photobiomodulation and Symptom Improvement

Polychromatic light therapy (PLT) delivers photon energy which  penetrates the skin and is translated into biological signaling. The process, called photobiomodulation (PBM), initiates a cascade of cellular responses. PBM triggers the release of nitric oxide (NO) – the “miracle molecule” of the human body and the body’s natural vasodilator. Nitric oxide dilates blood vessels and gently increases circulation (blood flow) throughout the body, delivering vital nutrients for tissue repair and health promotion.

A growing body of scientific evidence demonstrates PLT having beneficial responses on conditions including:

  • Inflammation
  • Wound healing
  • Arthritis pain
  • Neuropathy
  • Carpal Tunnel Syndrome
  • Mood disorders
  • Back pain, neck pain, and joint pain
  • Traumatic brain injuries
  • Acne, wrinkles, and hair loss
  • Muscle performance, fatigue, and recovery
  • Muscle sprains and strains
  • Sports injuries
  • Bruises and swelling

Evidence from Pain Application Research Articles

The Effect of Low-Level Laser Therapy on Knee Osteoarthritis


“Osteoarthritis (OA) is one of the most common joint disorders in the elderly which could be associated with considerable physical disability… In the current study, a significant reduction was observed regarding the nocturnal pain, pain on walking and ascending the steps, knee circumference, distance between the hip and heel, and knee to horizontal hip to heel distance at the end of the treatment course. In brief, the current study focuses on the fact that LLLT is effective in reducing pain in knee osteoarthritis.”

Soleimanpour, H., et al. (2014). “The effect of low-level laser therapy on knee osteoarthritis: prospective, descriptive study.” Lasers Med Sci 29(5): 1695-1700.

For more information, please view the full research study.

Effects of Photobiomodulation Therapy, Pharmacological Therapy, and Physical Exercise


“Osteoarthritis (OA) triggers increased levels of inflammatory markers, including prostaglandin (PG) E2 and proinflammatory cytokines. The elevation of cytokine levels is closely associated with increased articular tissue degeneration. Thus, the use of combination therapies may presumably be able to enhance the effects on the modulation of inflammatory markers. The present study aimed to evaluate and compare the effects of photobiomodulation therapy (PBMT), physical exercise, and topical nonsteroidal anti-inflammatory drug (NSAID) use on the inflammatory process after they were applied either alone or in different combinations. The results from the present study indicate that treatment with PBMT is more effective in modulating the inflammatory process underlying OA when compared with the other therapies tested.”

Tomazoni, S. S., et al. (2017). “Effects of photobiomodulation therapy, pharmacological therapy, and physical exercise as single and/or combined treatment on the inflammatory response induced by experimental osteoarthritis.” Lasers Med Sci 32(1): 101-108.

For more information, please view the full research study.

Photobiomodulation Therapy in the Modulation of Inflammatory Mediators and Bradykinin Receptors in an Experimental Model of Acute Osteoarthritis


“The objective of this study was to evaluate the effects of photobiomodulation therapy (PBMT) on inflammatory indicators, i.e., inflammatory mediators (TNF-alpha and CINC-1), and pain characterized by hyperalgesia and B1 and B2 receptor activation at 6, 24, and 48 h after papain-induced osteoarthritis (OA) in rats. We conclude that photobiomodulation therapy was able to promote the reduction of proinflammatory cytokines such as TNF-alpha and CINC-1, to reduce the gene and protein expression of the bradykinin receptor (B1 and B2), as well as increasing the stimulus response threshold of pressure in an experimental model of acute osteoarthritis.”

de Oliveira, V. L., et al. (2017). “Photobiomodulation therapy in the modulation of inflammatory mediators and bradykinin receptors in an experimental model of acute osteoarthritis.” Lasers Med Sci 32(1): 87-94.

For more information, please view the full research study.

Evidence from Neuropathy Application Research Articles

The Restorative Effects of Pulsed Infrared Light Therapy on Significant Loss of Peripheral Protective Sensation


“Pulsed infrared light therapy (PILT) has been shown to increase peripheral sensation in diabetic patients with diabetic peripheral neuropathy (DPN). However, most studies last for very short periods, with the subjects receiving only 6-20 treatments. The purpose of this study was to evaluate the effectiveness of an eight-week course of PILT in reversing long-standing, profound DPN in patients with type 1 and type 2 diabetes… Changes in peripheral protective sensation (PPS) were measured using Semmes-Weinstein monofilaments (SWM) ranging from 3.7 to 6.48. PILT improved PPS even in patients with long-standing chronic neuropathies whose initial pre-study sensation was not measurable with a 200-g SWM. PILT significantly improves PPS. While the exact mechanism of action is not understood, infrared light may improve peripheral neuropathies by improving foot perfusion by stimulating nitric oxide production.”

Arnall, D. A., et al. (2006). “The restorative effects of pulsed infrared light therapy on significant loss of peripheral protective sensation in patients with long-term type 1 and type 2 diabetes mellitus.” Acta Diabetol 43(1): 26-33.

For more information, please view the full research study.

Effects of Monochromatic Infrared Phototherapy in Patients with Diabetic Peripheral Neuropathy


“Monochromatic infrared energy (MIRE) or phototherapy has been used to improve plantar sensitivity and pain in lower limbs of patients with diabetic sensorimotor peripheral neuropathy (DSPN), but the available primary results are inconsistent. There was limited evidence that MIRE results in short-term improvement of tactile sensitivity probably not sustained over time. Limited evidence also suggested that MIRE does not provide relief for neuropathic pain. As quality of evidence is low, further studies are likely to change the estimated effect.”

Robinson, C. C., et al. (2017). “Effects of monochromatic infrared phototherapy in patients with diabetic peripheral neuropathy: a systematic review and meta-analysis of randomized controlled trials.” Braz J Phys Ther 21(4): 233-243.

For more information, please view the full research study.

Evidence from Beauty Application Research Articles

830 nm Light-Emitting Diode Low Level Light Therapy (LED-LLLT) Enhances Wound Healing: A Preliminary Study


“The application of light-emitting diodes in a number of clinical fields is expanding rapidly since the development in the late 1990s of the NASA LED. Wound healing is one field where low level light therapy with LEDs (LED-LLLT) has attracted attention for both accelerating wound healing and controlling sequelae. The present study evaluated LED-LLLT in 5 wounds of various etiologies. All patients were in varying degrees of pain. All wounds were treated with multiple sessions (daily, every other day or twice weekly) using an LED-LLLT system (830 nm, CW, irradiance of 100 mW/cm(2) and fluence of 60 J/cm(2)) till improvement was achieved… Full wound healing and control of infection and discomfort were achieved in all patients, with wound condition-mediated treatment periods ranging from 1 to 8 weeks… 830 nm LED-LLLT successfully brought about accelerated healing in wounds of different etiologies and at different stages, and successfully controlled secondary infection. LED-LLLT was easy and pain-free to apply, and was well-tolerated by all patients. The good results warrant the design of controlled studies with a larger patient population.”

Min, P. K. and B. L. Goo (2013). “830 nm light-emitting diode low level light therapy (LED-LLLT) enhances wound healing: a preliminary study.” Laser Ther 22(1): 43-49.

For more information, please view the full research study.

Light-Emitting Diode for Acne, Scars, and Photodamaged Skin


“Light-emitting diode therapy was discovered in the late 1960s but only recently has it been widely applied in dermatology to treat a wide range of skin diseases including photoaging, scars, and acne. Since the introduction of photobiostimulation into medicine, the effectiveness and applicability of a variety of light sources have thoroughly been investigated. Light-emitting diode photomodulation is a nonthermal technology used to modulate cellular activity with light, and the photons are absorbed by mitochondrial chromophores in skin cells. Various beneficial effects of light-emitting diode at relatively low intensities have been reported, especially in indications where stimulation of healing, reduction of pain and inflammation, restoration of function, and skin rejuvenation are required. The light-emitting diode therapy is safe, nontoxic, and noninvasive with no side effects reported in the published literature.”

Pitassi, L. (2016). “Light-Emitting Diode for Acne, Scars, and Photodamaged Skin.” Clinical Approaches and Procedures in Cosmetic Dermatology.

For more information, please view the full research study.

The Nuts and Bolts of Low-Level Laser (Light) Therapy


“Soon after the discovery of lasers in the 1960s it was realized that laser therapy had the potential to improve wound healing and reduce pain, inflammation and swelling. In recent years the field sometimes known as photobiomodulation has broadened to include light-emitting diodes and other light sources, and the range of wavelengths used now includes many in the red and near infrared. The term “low level laser therapy” or LLLT has become widely recognized and implies the existence of the biphasic dose response or the Arndt-Schulz curve. This review will cover the mechanisms of action of LLLT at a cellular and at a tissular level and will summarize the various light sources and principles of dosimetry that are employed in clinical practice. The range of diseases, injuries, and conditions that can be benefited by LLLT will be summarized with an emphasis on those that have reported randomized controlled clinical trials. Serious life-threatening diseases such as stroke, heart attack, spinal cord injury, and traumatic brain injury may soon be amenable to LLLT therapy.”

Chung, H., et al. (2012). “The nuts and bolts of low-level laser (light) therapy.” Ann Biomed Eng 40(2): 516-533.

For more information, please view the full research study.

Blue Light for Infectious Diseases: Propionibacterium Acnes, Helicobacter Pylori, and Beyond


“Blue light, particularly in the wavelength range of 405-470 nm, has attracted increasing attention due to its intrinsic antimicrobial effect without the addition of exogenous photosensitizers. In addition, it is commonly accepted that blue light is much less detrimental to mammalian cells than ultraviolet irradiation, which is another light-based antimicrobial approach being investigated. In this review, we discussed the blue light sensing systems in microbial cells, antimicrobial efficacy of blue light, the mechanism of antimicrobial effect of blue light, the effects of blue light on mammalian cells, and the effects of blue light on wound healing. It has been reported that blue light can regulate multi-cellular behavior involving cell-to-cell communication via blue light receptors in bacteria, and inhibit biofilm formation and subsequently potentiate light inactivation. At higher radiant exposures, blue light exhibits a broad-spectrum antimicrobial effect against both Gram-positive and Gram-negative bacteria. Blue light therapy is a clinically accepted approach for Propionibacterium acnes infections. Clinical trials have also been conducted to investigate the use of blue light for Helicobacter pylori stomach infections and have shown promising results…”

Dai, T., et al. (2012). “Blue light for infectious diseases: Propionibacterium acnes, Helicobacter pylori, and beyond?” Drug Resist Update 15(4): 223-236.

For more information, please view the full research study.

Evidence from Health & Wellness Application Research Articles

Light-Emitting Diode Therapy (LEDT) Improves Functional Capacity in Rats with Heart Failure


“The syndrome of heart failure (HF) promotes central and peripheral dysfunctions that result in functional capacity decrease, leading to fatigue, dyspnea, and exercise intolerance. The use of light-emitting diode therapy (LEDT) has shown good results reducing fatigue and exercise intolerance, when applied on skeletal muscles before or after exercises. Comparing the percentage difference (Delta) between baseline and the final ET, there was no significant difference for the VO2max variable considering all groups. However, Sham and LEDT-HF groups showed higher relative values than the Control-HF group, respectively, for distance covered (27.7 and 32.5 %), time of exercise test (17.7 and 20.5 %), and speed (13.6 and 12.2 %). In conclusion, LEDT was able to increase the functional capacity evaluated by distance covered, time, and speed of exercise in rats with HF.”

Capalonga, L., et al. (2016). “Light-emitting diode therapy (LEDT) improves functional capacity in rats with heart failure.” Lasers Med Sci 31(5): 937-944.

For more information, please view the full research study.

Role of Low-Level Laser Therapy in Neurorehabilitation


“This year marks the 50th anniversary of the discovery of the laser. The development of lasers for medical use, which became known as low-level laser therapy (LLLT) or photobiomodulation, followed in 1967. In recent years, LLLT has become an increasingly mainstream modality, especially in the areas of physical medicine and rehabilitation. At first used mainly for wound healing and pain relief, the medical applications of LLLT have broadened to include diseases such as stroke, myocardial infarction, and degenerative or traumatic brain disorders. This review will cover the mechanisms of LLLT that operate both on a cellular and a tissue level. Animal studies and human clinical trials of LLLT for indications with relevance to neurology, such as stroke, traumatic brain injury, degenerative brain disease, spinal cord injury, and peripheral nerve regeneration, will be covered.”

Hashmi, J. T., et al. (2010). “Role of low-level laser therapy in neurorehabilitation.” PM R 2(12 Suppl 2): S292-305.

For more information, please view the full research study.

Cognitive Enhancement by Transcranial Laser Stimulation and Acute Aerobic Exercise


“This is the first randomized, controlled study comparing the cognitive effects of transcranial laser stimulation and acute aerobic exercise on the same cognitive tasks. We examined whether transcranial infrared laser stimulation of the prefrontal cortex, acute high-intensity aerobic exercise, or the combination may enhance performance in sustained attention and working memory tasks. The transcranial infrared laser stimulation and acute aerobic exercise treatments were similarly effective for cognitive enhancement, suggesting that they augment prefrontal cognitive functions similarly.”

Hwang, J., et al. (2016). “Cognitive enhancement by transcranial laser stimulation and acute aerobic exercise.” Lasers Med Sci 31(6): 1151-1160.

For more information, please view the full research study.

Transcranial Low-Level Laser Therapy Improves Brain Mitochondrial Function and Cognitive Impairment in D-Galactose-Induced Aging Mice


“Mitochondrial function plays a key role in the aging-related cognitive impairment, and photoneuromodulation of mitochondria by transcranial low-level laser therapy (LLLT) may contribute to its improvement. This study focused on the transcranial LLLT effects on the D-galactose (DG)-induced mitochondrial dysfunction, apoptosis, and cognitive impairment in mice. This data indicates that transcranial LLLT at both of red and NIR wavelengths at the fluency of 8 J/cm2 has a potential to ameliorate aging-induced mitochondrial dysfunction, apoptosis, and cognitive impairment.”

Salehpour, F., et al. (2017). “Transcranial low-level laser therapy improves brain mitochondrial function and cognitive impairment in D-galactose-induced aging mice.” Neurobiol Aging 58: 140-150.

For more information, please view the full research study.

Shining Light on the Head: Photobiomodulation for Brain Disorders


“Photobiomodulation (PBM) describes the use of red or near-infrared light to stimulate, heal, regenerate, and protect tissue that has either been injured, is degenerating, or else is at risk of dying. One of the organ systems of the human body that is most necessary to life, and whose optimum functioning is most worried about by humankind in general, is the brain. The brain suffers from many different disorders that can be classified into three broad groupings: traumatic events (stroke, traumatic brain injury, and global ischemia), degenerative diseases (dementia, Alzheimer’s and Parkinson’s), and psychiatric disorders (depression, anxiety, post traumatic stress disorder). There is some evidence that all these seemingly diverse conditions can be beneficially affected by applying light to the head. There is even the possibility that PBM could be used for cognitive enhancement in normal healthy people.”

Hamblin, M. R. (2016). “Shining light on the head: Photobiomodulation for brain disorders.” BBA Clin 6: 113-124.

For more information, please view the full research study.

Evidence from Sport Application Research Articles

Low-Level Laser (Light) Therapy (LLLT) on Muscle Tissue: Performance, Fatigue and Repair Benefited by the Power of Light


“The use of low level laser (light) therapy (LLLT) has recently expanded to cover areas of medicine that were not previously thought of as the usual applications such as wound healing and inflammatory orthopedic conditions. One of these novel application areas is LLLT for muscle fatigue and muscle injury. Since it is becoming agreed that mitochondria are the principal photoacceptors present inside cells, and it is known that muscle cells are exceptionally rich in mitochondria, this suggests that LLLT should be highly beneficial in muscle injuries. The ability of LLLT to stimulate stem cells and progenitor cells means that muscle satellite cells may respond well to LLLT and help muscle repair. Furthermore the ability of LLLT to reduce inflammation and lessen oxidative stress is also beneficial in cases of muscle fatigue and injury.”

Ferraresi, C., et al. (2012). “Low-level laser (light) therapy (LLLT) on muscle tissue: performance, fatigue and repair benefited by the power of light.” Photonics Lasers Med. 1(4): 267-286.

For more information, please view the full research study.

Light-Emitting Diode Therapy in Exercise-Trained Mice Increases Muscle Performance, Cytochrome Oxidase Activity, ATP and Cell Proliferation


“Light-emitting diode therapy (LEDT) applied over the leg, gluteus and lower-back muscles of mice using a LED cluster (630 nm and 850 nm, 80 mW/cm(2) , 7.2 J/cm(2) ) increased muscle performance (repetitive climbing of a ladder carrying a water-filled tube attached to the tail), ATP and mitochondrial metabolism; oxidative stress and proliferative myocyte markers in mice subjected to acute and progressive strength training. Six bi-daily training sessions LEDT-After and LEDT-Before-After regimens more than doubled muscle performance and increased ATP more than tenfold. The effectiveness of LEDT on improving muscle performance and recovery suggest applicability for high performance sports and in training programs. Positioning of the mice and light-emitting diode therapy (LEDT) applied on mouse legs, gluteus and lower-back muscles without contact.”

Ferraresi, C., et al. (2015). “Light-emitting diode therapy in exercise-trained mice increases muscle performance, cytochrome c oxidase activity, ATP and cell proliferation.” J Biophotonics 8(9): 740-754.

For more information, please view the full research study.

Long-Term Low-Level Laser Therapy Promotes an Increase in Maximal Oxygen Uptake and Exercise Performance in a Dose-Dependent Manner in Wistar Rats


“The use of low-level laser therapy (LLLT) represents a new intervention modality that has been explored to enhance exercise performance. The aim of this study was to evaluate the influence of LLLT (GaAIAs-850 nm) at different doses on VO2max and on exercise performance in rats… No significant results were found comparing before and after conditions for the studied variables considering P-LLLT and 8.7 J/cm(2)-LLLT groups. The LLLT promoted in a dose-dependent manner an increase in oxygen consumption uptake and a performance increment of male Wistar rats.”

Perini, J. L., et al. (2016). “Long-term low-level laser therapy promotes an increase in maximal oxygen uptake and exercise performance in a dose-dependent manner in Wistar rats.” Lasers Med Sci 31(2): 241-248.

For more information, please view the full research study.