Endre Mester {{PD-US-expired}} The use of light for treatment has been known for thousands of years. In the early 20th century, exposure to the sun and other light sources began to be researched more frequently. Now over 6,000 studies on Low-Level Light Therapy, now called Photobiomodulation (photo bio modulation), all suggest the same thing – Photobiomodulation Therapy can help with various conditions and diseases, such as dementia, tuberculosis, lupus vulgaris, acne, and some tissue problems.

Although photobiomodulation research so far has shown impressive results in supporting a variety of conditions, more studies are needed to determine the full scale of its capabilities.

Photobiomodulation Research Articles

The possibility of using light to stimulate wound healing and cellular growth has created a new wellness treatment referred to as Photobiomodulation Therapy. Since the discovery in 1967 by Endre Mester, researchers have worked to uncover the scientific basis for this phenomenon and establish the range of optical exposure parameters that lead to successful clinical outcomes.

Read what researchers from Mass General, Harvard and Boston University conclude about LED Light Therapy.

Photobiomodulation is continuing to make significant progress in obtaining recognition from authorities in medical schools, scholarly journals, the media, medical practitioners, therapists, and other bodies concerned with biomedical science.

Biphasic dose response in low level light therapy

Dose Response. 2009 Sep 1;7(4):358-83. doi: 10.2203/dose-response.09-027.Hamblin.

There have been a large number of both animal model and clinical studies that demonstrated highly beneficial LLLT effects on a variety of diseases, injuries, and has been widely used in both chronic and acute conditions (see Figure 7). LLLT may enhance neovascularisation, promote angiogenesis and increase collagen synthesis to promote healing of acute (Hopkins et al. 2004) and chronic wounds (Yu et al. 1997). LLLT provided acceleration of cutaneous wound healing in rats with a biphasic dose response favoring lower doses (Corazza et al. 2007). LLLT can also stimulate healing of deeper structures such as nerves (Gigo-Benato et al.2004), tendons (Fillipin et al. 2005), cartilage (Morrone et al. 2000), bones (Weberet al. 2006) and even internal organs (Shao et al. 2005). LLLT can reduce pain (Bjordal et al. 2006a), inflammation (Bjordal et al. 2006b) and swelling (Carati et al. 2003) caused by injuries, degenerative diseases or autoimmune diseases. Oron reported beneficial effect of LLLT on repair processes after injury or ischemia in skeletal and heart muscles in multiple animal models in vivo (Ad and Oron 2001Oron et al. 2001aOron et al. 2001bYaakobi et al. 2001). LLLT has been used to mitigate damage after strokes (in both animals (Lapchak et al. 2008) and humans (Lampl et al. 2007), after traumatic brain injury (Oron et al. 2007) and after spinal cord injury (Wu et al. 2009).
Read the full reasearch PMID: 20011653

Energy / Mitochondrial Function

Mitochondrial signal transduction in accelerated wound and retinal healing by near-infrared light therapy

Mitochondrion . 2004 Sep;4(5-6):559-67. doi: 10.1016/j.mito.2004.07.033


Photobiomodulation by light in the red to near infrared range (630-1000 nm) using low energy lasers or light-emitting diode (LED) arrays has been shown to accelerate wound healing, improve recovery from ischemic injury in the heart and attenuate degeneration in the injured optic nerve. Recent evidence indicates that the therapeutic effects of red to near infrared light result, in part, from intracellular signaling mechanisms triggered by the interaction of NIR light with the mitochondrial photoacceptor molecule cytochrome c oxidase. We have demonstrated that NIR-LED photo-irradiation increases the production of cytochrome oxidase in cultured primary neurons and reverses the reduction of cytochrome oxidase activity produced by metabolic inhibitors. We have also shown that NIR-LED treatment prevents the development of oral mucositis in pediatric bone marrow transplant patients. Photobiomodulation improves wound healing in genetically diabetic mice by upregulating genes important in the promotion of wound healing. More recent studies have provided evidence for the therapeutic benefit of NIR-LED treatment in the survival and functional recovery of the retina and optic nerve in vivo after acute injury by the mitochondrial toxin, formic acid generated in the course of methanol intoxication. Gene discovery studies conducted using microarray technology documented a significant upregulation of gene expression in pathways involved in mitochondrial energy production and antioxidant cellular protection. These findings provide a link between the actions of red to near infrared light on mitochondrial oxidative metabolism in vitro and cell injury in vivo. Based on these findings and the strong evidence that mitochondrial dysfunction is involved in the pathogenesis of numerous diseases processes, we propose that NIR-LED photobiomodulation represents an innovative and non-invasive therapeutic approach for the treatment of tissue injury and disease processes in which mitochondrial dysfunction is postulated to play a role including diabetic retinopathy, age-related macular degeneration, Leber’s hereditary optic neuropathy and Parkinson’s disease.

Read the full reasearch PMID: 16120414

Inflammation & Auto-Immune Disease

Effect of Pulsing in Low-Level Light Therapy

Lasers Surg Med . 2010 Aug;42(6):450-66. doi: 10.1002/lsm.20950.


Background and Objective
Low level light (or laser) therapy (LLLT) is a rapidly growing modality used in physical therapy, chiropractic, sports medicine and increasingly in mainstream medicine. LLLT is used to increase wound healing and tissue regeneration, to relieve pain and inflammation, to prevent tissue death, to mitigate degeneration in many neurological indications. While some agreement has emerged on the best wavelengths of light and a range of acceptable dosages to be used (irradiance and fluence), there is no agreement on whether continuous wave or pulsed light is best and on what factors govern the pulse parameters to be chosen.

Study Design/Materials and Methods
The published peer-reviewed literature was reviewed between 1970 and 2010.

The basic molecular and cellular mechanisms of LLLT are discussed. The type of pulsed light sources available and the parameters that govern their pulse structure are outlined. Studies that have compared continuous wave and pulsed light in both animals and patients are reviewed. Frequencies used in other pulsed modalities used in physical therapy and biomedicine are compared to those used in LLLT.

There is some evidence that pulsed light does have effects that are different from those of continuous wave light. However further work is needed to define these effects for different disease conditions and pulse structures.


Read the full reasearch PMCID: PMC2933784

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 . 2017 Jan;32(1):101-108. doi: 10.1007/s10103-016-2091-8. Epub 2016 Oct 10.


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. OA was induced by intra-articular papain injection in the knee of rats. After 21 days, the animals began treatment with a topical NSAID and/or with physical exercise and/or PBMT. Treatments were performed three times a week for eight consecutive weeks, totaling 24 therapy sessions. Analysis of real-time polymerase chain reaction (RT-PCR) gene expression; interleukin (IL)-1β, IL-6, and tumor necrosis factor alpha (TNF-α) protein expression; and PGE2 levels by enzyme-linked immunosorbent assay (ELISA) was conducted. Our results showed that PBMT alone and Exerc + PBMT significantly reduced IL-1β gene expression (p < 0.05) while no treatment changed both IL-6 and TNF-α gene expression. Treatment with NSAID alone, PBMT alone, Exerc + PBMT, and NSAID + PBMT reduced IL-1β protein expression (p < 0.05). All therapies significantly reduced IL-6 and TNF-α protein expression (p < 0.05) compared with the OA group. Similarly, all therapies, except Exerc, reduced the levels of PGE2 (p < 0.05) compared with the OA group. 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.

Read the full reasearch PMID: 27726040

The Efficacy and Safety of 660 nm and 411 to 777 nm Light-Emitting Devices for Treating Wrinkles

Dermatol Surg . 2017 Mar;43(3):371-380. doi: 10.1097/DSS.0000000000000981.


Background: Low-level light therapy (LLLT) using light-emitting diodes (LEDs) is considered to be helpful for skin regeneration and anti-inflammation.

Objective: To evaluate the efficacy and safety of 2 types of LLLTs using 660 nm-emitting red LEDs and 411 to 777 nm-emitting white LEDs in the treatment of facial wrinkles.

Materials and methods: A prospective, randomized, double-blinded, comparative clinical trial involving 52 adult female subjects was performed. The faces of the subjects were irradiated daily with 5.17 J of red or white LEDs for 12 weeks.

Results: In both groups treated with red and white LEDs, the wrinkle measurement from skin replica improved significantly from baseline at Week 12. The red LED group showed slightly better improvement, but there were no statistical differences. In assessments by blinded dermatologists, no significant differences were observed in both groups. In the global assessment of the subjects, the mean improvement score of the red LED group was higher than that of the white LED group.

Conclusion: Low-level light therapy using 660 nm LEDs or 411 to 777 nm LEDs significantly improved periocular wrinkles. Especially, 660 nm LEDs could be an effective and tolerable treatment option for wrinkles.

Read the full reasearch PMID: 28195844

Weight Loss

The effects of exercise training associated with low-level laser therapy on biomarkers of adipose tissue transdifferentiation in obese women

Lasers Med Sci. 2018 Aug;33(6):1245-1254. doi: 10.1007/s10103-018-2465-1. Epub 2018 Feb 23.


Improvements in body mass, BMI, body fat mass, lean mass, visceral fat, waist circumference, insulin, HOMA-IR, total cholesterol, LDL-cholesterol, triglycerides, and ANP in both groups were demonstrated. Only the Phototherapy group showed a reduction in interleukin-6 and an increase in WNT5 signaling. In addition, it was possible to observe a higher magnitude change for the fat mass, insulin, HOMA-IR, and FGF-21 variables in the Phototherapy group. In the present investigation, it was demonstrated that exercise training associated with LLLT promotes an improvement in body composition and inflammatory processes as previously demonstrated. The Phototherapy group especially presented positive modifications of WNT5 signaling, FGF-21, and ANP, possible biomarkers associated with browning adiposity processes. This suggests that this kind of intervention promotes results applicable in clinical practice to control obesity and related comorbidities.

Read the full reasearch PMID: 29473115

The potential of phototherapy to reduce body fat, insulin resistance and “metabolic inflexibility” related to obesity in women undergoing weight loss treatment

Lasers Surg Med. 2015 Oct;47(8):634-42. doi: 10.1002/lsm.22395. Epub 2015 Jul 29.


Our results demonstrated for the first time that phototherapy enhances the physical exercise effects in obese women undergoing weight loss treatment promoting significant changes in inflexibility metabolic profile.

Read the full reasearch PMID: 26220050

Minor Aches & Pain

A systematic review of low level laser therapy with location-specific doses for pain from chronic joint disorders

Aust J Physiother. 2003;49(2):107-16.


We investigated if low level laser therapy (LLLT) of the joint capsule can reduce pain in chronic joint disorders. A literature search identified 88 randomised controlled trials, of which 20 trials included patients with chronic joint disorders. Six trials were excluded for not irradiating the joint capsule. Three trials used doses lower than a dose range nominated a priori for reducing inflammation in the joint capsule. These trials found no significant difference between active and placebo treatments. The remaining 11 trials including 565 patients were of acceptable methodological quality with an average PEDro score of 6.9 (range 5-9). In these trials, LLLT within the suggested dose range was administered to the knee, temporomandibular or zygapophyseal joints. The results showed a mean weighted difference in change of pain on VAS of 29.8 mm (95% CI, 18.9 to 40.7) in favour of the active LLLT groups. Global health status improved for more patients in the active LLLT groups ( relative risk of 0.52; 95% CI 0.36 to 0.76). Low level laser therapy with the suggested dose range significantly reduces pain and improves health status in chronic joint disorders, but the heterogeneity in patient samples, treatment procedures and trial design calls for cautious interpretation of the results.

Read the full reasearch PMID: 12775206

Low-level laser therapy to treat fibromyalgia

Lasers Med Sci . 2014 Nov;29(6):1815-9. doi: 10.1007/s10103-014-1566-8. Epub 2014 May 7.


Several clinical treatments have been proposed to manage symptoms of fibromyalgia. Low-level laser therapy (LLLT) may be a useful tool to treat this dysfunction. The aim of this study was to evaluate the effects of LLLT in patients with fibromyalgia. A placebo-controlled, randomized clinical trial was carried out with 20 patients divided randomly into either an LLLT group (n = 10) or a placebo group (n = 10). The LLLT group was treated with a GaAlAs laser (670 nm, 4 J/cm(2) on 18 tender points) three times a week over 4 weeks. Before and after treatment, patients were evaluated with the Fibromyalgia Impact Questionnaire (FIQ), McGill Pain Questionnaire, and visual analog scale (VAS). Data from the FIQ and McGill questionnaire for the treated and control groups were analyzed by paired t tests, and Wilcoxon tests were used to analyze data from the VAS. After LLLT or sham treatment, the number of tender points was significantly reduced in both groups (LLLT, p < 0.0001; placebo, p = 0.0001). However, all other fibromyalgia symptoms showed significant improvements after LLLT compared to placebo (FIQ, p = 0.0003; McGill, p = 0.0078; and VAS, p = 0.0020). LLLT provided relief from fibromyalgia symptoms in patients and should be further investigated as a therapeutic tool for management in fibromyalgia.

Read the full reasearch PMID: 24801056

Photobiomodulation therapy (PBMT) on acute pain and inflammation in patients who underwent total hip arthroplasty-a randomized, triple-blind, placebo-controlled clinical trial

Lasers Med Sci. 2018 Dec;33(9):1933-1940. doi: 10.1007/s10103-018-2558-x. Epub 2018 Jun 16.


When conservative treatments fail, hip osteoarthritis (OA), a chronic degenerative disease characterized by cartilage wear, progressive joint deformity, and loss of function, can result in the need for a total hip arthroplasty (THA). Surgical procedures induced tissue trauma and incite an immune response. Photobiomodulation therapy (PBMt) using low-level laser therapy (LLLT) and/or light-emitting diode therapy (LEDT) has proven effective in tissue repair by modulating the inflammatory process and promoting pain relief. Therefore, the aim of this study was to analyze the immediate effect of PBMt on inflammation and pain of patients undergoing total hip arthroplasty. The study consisted of 18 post-surgical hip arthroplasty patients divided into two groups (n = 9 each) placebo and active PBMt who received one of the treatments in a period from 8 to 12 h following THA surgery. PBMt (active or placebo) was applied using a device consisting of nine diodes (one super-pulsed laser of 905 nm, four infrared LEDs of 875 nm, and four red LEDs 640 nm, 40.3 J per point) applied to 5 points along the incision. Visual analog scale (VAS) and blood samples for analysis of the levels of the cytokines TNF-α, IL-6, and IL-8 were recorded before and after PBMt application. The values for the visual analog scale as well as those in the analysis of TNF-α and IL-8 serum levels decreased in the active PBMt group compared to placebo-control group (p < 0.05). No decrease was observed for IL-6 levels. We conclude that PBMt is effective in decreasing pain intensity and post-surgery inflammation in patients receiving total hip arthroplasty.

Read the full reasearch PMID: 29909435


Photobiomodulation in human muscle tissue: an advantage in sports performance?

J Biophotonics . 2016 Dec;9(11-12):1273-1299. doi: 10.1002/jbio.201600176. Epub 2016 Nov 22.


Photobiomodulation (PBM) describes the use of red or near-infrared (NIR) light to vstimulate, heal, and regenerate damaged tissue. Both pre-conditioning (light delivered to muscles before exercise) and PBM applied after exercise can increase sports performance in athletes. This review covers the effects of PBM on human muscle tissue in clinical trials in volunteers related to sports performance and in athletes. The parameters used were categorized into those with positive effects or no effects on muscle performance and recovery. Randomized controlled trials and case-control studies in both healthy trained and untrained participants, and elite athletes were retrieved from MEDLINE up to 2016. Performance metrics included fatigue, number of repetitions, torque, hypertrophy; measures of muscle damage and recovery such as creatine kinase and delayed onset muscle soreness. Searches retrieved 533 studies, of which 46 were included in the review (n=1045 participants). Studies used single laser probes, cluster of laser-diodes, LED-clusters, mixed clusters (lasers and LEDs), and flexible LED arrays. Both red, NIR, and red/NIR mixtures were used. PBM can increase muscle mass gained after training, and decrease inflammation and oxidative stress in muscle biopsies. We raise the question of whether PBM should be permitted in athletic competition by international regulatory authorities.

Read the full reasearch PMCID: PMC5167494

Pre-Conditioning with Low-Level Laser (Light) Therapy: Light Before the Storm

Dose Response . 2014 Sep 22;12(4):619-49. doi: 10.2203/dose-response.14-032.Agrawal. eCollection 2014 Dec.


Pre-conditioning by ischemia, hyperthermia, hypothermia, hyperbaric oxygen (and numerous other modalities) is a rapidly growing area of investigation that is used in pathological conditions where tissue damage may be expected. The damage caused by surgery, heart attack, or stroke can be mitigated by pre-treating the local or distant tissue with low levels of a stress-inducing stimulus, that can induce a protective response against subsequent major damage. Low-level laser (light) therapy (LLLT) has been used for nearly 50 years to enhance tissue healing and to relieve pain, inflammation and swelling. The photons are absorbed in cytochrome(c) oxidase (unit four in the mitochondrial respiratory chain), and this enzyme activation increases electron transport, respiration, oxygen consumption and ATP production. A complex signaling cascade is initiated leading to activation of transcription factors and up- and down-regulation of numerous genes. Recently it has become apparent that LLLT can also be effective if delivered to normal cells or tissue before the actual insult or trauma, in a pre-conditioning mode. Muscles are protected, nerves feel less pain, and LLLT can protect against a subsequent heart attack. These examples point the way to wider use of LLLT as a pre-conditioning modality to prevent pain and increase healing after surgical/medical procedures and possibly to increase athletic performance.

Read the full reasearch PMC4267453

Nerve Function & Repair

“Quantum Leap” in Photobiomodulation Therapy Ushers in a New Generation of Light-Based Treatments for Cancer and Other Complex Diseases: Perspective and Mini-Review

Photomed Laser Surg . 2016 Mar;34(3):93-101. doi: 10.1089/pho.2015.4015. Epub 2016 Feb 18.


Objective: Set within the context of the 2015 International Year of Light and Light-Based Technologies,and of a growing and aging world population with ever-rising healthcare needs, this perspective and mini-review focuses on photobiomodulation (PBM) therapy as an emerging, cost-effective, treatment option for cancer (i.e., solid tumors) and other complex diseases, particularly, of the eye (e.g., age-related macular degeneration, diabetic retinopathy, glaucoma, retinitis pigmentosa) and the central nervous system (e.g., Alzheimer’s and Parkinson’s disease).

Background data: Over the last decades, primary and secondary mechanisms of PBM have been revealed. These include oxygen-dependent and oxygen-independent structural and functional action pathways. Signal and target characteristics determine biological outcome, which is optimal (or even positive) only within a given set of parameters.

Methods: This study was a perspective and nonsystematic literature mini-review.

Results: Studies support what we describe as a paradigm shift or “quantum leap” in the understanding and use of light and its interaction with water and other relevant photo-cceptors to restore physiologic function.

Conclusions: Based on existing evidence, it is argued that PBM therapy can raise the standard of care and improve the quality of life of patients for a fraction of the cost of many current approaches. PBM therapy can, therefore,benefit large, vulnerable population groups, including the elderly and the poor, whilehaving a major impact on medical practice and public finances.

Read the full reasearch PMCID: PMC4782038

Other Researches

Near infrared light protects cardiomyocytes from hypoxia and reoxygenation injury by a nitric oxide dependent mechanism

J Mol Cell Cardiol . 2009 Jan;46(1):4-14. doi: 10.1016/j.yjmcc.2008.09.707. Epub 2008 Sep 30.


Photobiomodulation with near infrared light (NIR) provides cellular protection in various disease models. Previously, infrared light emitted by a low-energy laser has been shown to significantly improve recovery from ischemic injury of the canine heart. The goal of this investigation was to test the hypothesis that NIR (670 nm) from light emitting diodes produces cellular protection against hypoxia and reoxygenation-induced cardiomyocyte injury. Additionally, nitric oxide (NO) was investigated as a potential cellular mediator of NIR. Our results demonstrate that exposure to NIR at the time of reoxygenation protects neonatal rat cardiomyocytes and HL-1 cells from injury, as assessed by lactate dehydrogenase release and MTT assay. Similarly, indices of apoptosis, including caspase 3 activity, annexin binding and the release of cytochrome c from mitochondria into the cytosol, were decreased after NIR treatment. NIR increased NO in cardiomyocytes, and the protective effect of NIR was completely reversed by the NO scavengers carboxy-PTIO and oxyhemoglobin, but only partially blocked by the NO synthase (NOS) inhibitor L-NMMA. Mitochondrial metabolism, measured by ATP synthase activity, was increased by NIR, and NO-induced inhibition of oxygen consumption with substrates for complex I or complex IV was reversed by exposure to NIR. Taken together these data provide evidence for protection against hypoxia and reoxygenation injury in cardiomyocytes by NIR in a manner that is dependent upon NO derived from NOS and non-NOS sources.

Read the full reasearch PMCID: PMC2640422

Shedding light on a new treatment for diabetic wound healing: a review on phototherapy

ScientificWorldJournal . 2014 Jan 6;2014:398412. doi: 10.1155/2014/398412. eCollection 2014.


Impaired wound healing is a common complication associated with diabetes with complex pathophysiological underlying mechanisms and often necessitates amputation. With the advancement in laser technology, irradiation of these wounds with low-intensity laser irradiation (LILI) or phototherapy, has shown a vast improvement in wound healing. At the correct laser parameters, LILI has shown to increase migration, viability, and proliferation of diabetic cells in vitro; there is a stimulatory effect on the mitochondria with a resulting increase in adenosine triphosphate (ATP). In addition, LILI also has an anti-inflammatory and protective effect on these cells. In light of the ever present threat of diabetic foot ulcers, infection, and amputation, new improved therapies and the fortification of wound healing research deserves better prioritization. In this review we look at the complications associated with diabetic wound healing and the effect of laser irradiation both in vitro and in vivo in diabetic wound healing.

Read the full reasearch PMCID: PMC3913345

Skin & Aesthetics

Combination of low level light therapy and nitrosyl-cobinamide accelerates wound healing

J Biomed Opt . 2015 May;20(5):051022. doi: 10.1117/1.JBO.20.5.051022.


Low level light therapy (LLLT) has numerous therapeutic benefits, including improving wound healing, but the precise mechanisms involved are not well established; in particular, the underlying role of cytochrome C oxidase (C-ox) as the primary photoacceptor and the associated biochemical mechanisms still require further investigation. We previously showed the nitric oxide (NO) donating drug nitrosyl-cobinamide (NO-Cbi) enhances wound healing through a cGMP/cGMP-dependent protein kinase/ERK1/2 mechanism. Here, we show that the combination of LLLT and NO-Cbi markedly improves wound healing compared to either treatment alone. LLLT-enhanced wound healing proceeded through an electron transport chain-C-ox-dependent mechanism with a reduction of reactive oxygen species and increased adenosine triphosphate production. C-ox was validated as the primary photoacceptor by three observations: increased oxygen consumption, reduced wound healing in the presence of sodium azide, and disassociation of cyanide, a known C-ox ligand, following LLLT. We conclude that LLLT and NO-Cbi accelerate wound healing through two independent mechanisms, the electron transport chain-C-ox pathway and cGMP signaling, respectively, with both resulting in ERK1/2 activation.

Read the full reasearch PMCID: PMC4284311

Green light emitting diodes accelerate wound healing: characterization of the effect and its molecular basis in vitro and in vivo

Wound Repair Regen . Mar-Apr 2012;20(2):226-35. doi: 10.1111/j.1524-475X.2012.00771.x.


Because light-emitting diodes (LEDs) are low-coherent, quasimonochromatic, and nonthermal, they are an alternative for low level laser therapy, and have photobiostimulative effects on tissue repair. However, the molecular mechanism(s) are unclear, and potential effects of blue and/or green LEDs on wound healing are still unknown. Here, we investigated the effects of red (638 nm), blue (456 nm), and green (518 nm) LEDs on wound healing. In an in vivo study, wound sizes in the skin of ob/ob mice were significantly decreased on day 7 following exposure to green LEDs, and complete reepithelialization was accelerated by red and green LEDs compared with the control mice. To better understand the molecular mechanism(s) involved, we investigated the effects of LEDs on human fibroblasts in vitro by measuring mRNA and protein levels of cytokines secreted by fibroblasts during the process of wound healing and on the migration of HaCat keratinocytes. The results suggest that some cytokines are significantly increased by exposure to LEDs, especially leptin, IL-8, and VEGF, but only by green LEDs. The migration of HaCat keratinocytes was significantly promoted by red or green LEDs. In conclusion, we demonstrate that green LEDs promote wound healing by inducing migratory and proliferative mediators, which suggests that not only red LEDs but also green LEDs can be a new powerful therapeutic strategy for wound healing.

Read the full reasearch PMID: 22380691

Inhibitory effect of 660-nm LED on melanin synthesis in in vitro and in vivo

Photodermatol Photoimmunol Photomed . 2017 Jan;33(1):49-57. doi: 10.1111/phpp.12276. Epub 2016 Nov 3.


Background: Skin hyperpigmentary disorders including postinflammatory hyperpigmentation, melasma, solar lentigines, and conditions like freckles are common. The light-emitting diodes (LEDs) are the latest category of nonthermal and noninvasive phototherapy to be considered in skin pigmentation disorder treatment.

Purpose: The purpose of this study was to investigate the effects of 660-nm LED on inhibition of melanogenesis. We investigated whether a 660-nm LED affected melanin synthesis in in vitro and in vivo models, and we explored the mechanisms involved.

Methods: The inhibitory effect of 660-nm LED on melanin synthesis was evaluated in B16F10 cells and HRM-2 melanin-possessing hairless mice were used to evaluate the antimelanogenic effects of 660-nm LED.

Results: Interestingly, 660-nm LED inhibited alpha-melanocyte-stimulating hormone-induced tyrosinase activity in B16F10 cells. We also found that 660-nm LED decreased MITF and tyrosinase expression and induced the activation of ERK. These findings suggest that the depigmenting effects of 660-nm LED result from downregulation of MITF and tyrosinase expression due to increased ERK activity. The 660-nm LED reduced UVB-induced melanogenesis in the skin of HRM-2 via downregulation of tyrosinase and MITF.

Conclusion: These findings suggest 660-nm LED is a potentially depigmentation strategy

Read the full reasearch PMID: 27696509

Is light-emitting diode phototherapy (LED-LLLT) really effective?

Laser Ther . 2011;20(3):205-15. doi: 10.5978/islsm.20.205.


Background: Low level light therapy (LLLT) has attracted attention in many clinical fields with a new generation of light-emitting diodes (LEDs) which can irradiate large targets. To pain control, the first main application of LLLT, have been added LED-LLLT in the accelerated healing of wounds, both traumatic and iatrogenic, inflammatory acne and the patient-driven application of skin rejuvenation.

Rationale and Applications: The rationale behind LED-LLLT is underpinned by the reported efficacy of LED-LLLT at a cellular and subcellular level, particularly for the 633 nm and 830 nm wavelengths, and evidence for this is presented. Improved blood flow and neovascularization are associated with 830 nm. A large variety of cytokines, chemokines and macromolecules can be induced by LED phototherapy. Among the clinical applications, non-healing wounds can be healed through restoring the collagenesis/collagenase imbalance in such examples, and ‘normal’ wounds heal faster and better. Pain, including postoperative pain, postoperative edema and many types of inflammation can be significantly reduced.

Experimental and clinical evidence: Some personal examples of evidence are offered by the first author, including controlled animal models demonstrating the systemic effect of 830 nm LED-LLLT on wound healing and on induced inflammation. Human patients are presented to illustrate the efficacy of LED phototherapy on treatment-resistant inflammatory disorders.

Conclusions: Provided an LED phototherapy system has the correct wavelength for the target cells, delivers an appropriate power density and an adequate energy density, then it will be at least partly, if not significantly, effective. The use of LED-LLLT as an adjunct to conventional surgical or nonsurgical indications is an even more exciting prospect. LED-LLLT is here to stay.

Read the full reasearch PMCID: PMC3799034

Low-level laser (light) therapy (LLLT) in skin: stimulating, healing, restoring

Semin Cutan Med Surg . 2013 Mar;32(1):41-52.


Low-level laser (light) therapy (LLLT) is a fast-growing technology used to treat a multitude of conditions that require stimulation of healing, relief of pain and inflammation, and restoration of function. Although the skin is the organ that is naturally exposed to light more than any other organ, it still responds well to red and near-infrared wavelengths. The photons are absorbed by mitochondrial chromophores in skin cells. Consequently electron transport, adenosine triphosphate (ATP) nitric oxide release, blood flow, reactive oxygen species increase and diverse signaling pathways get activated. Stem cells can be activated allowing increased tissue repair and healing. In dermatology, LLLT has beneficial effects on wrinkles, acne scars, hypertrophic scars, and healing of burns. LLLT can reduce UV damage both as a treatment and as a prophylaxis. In pigmentary disorders such as vitiligo, LLLT can increase pigmentation by stimulating melanocyte proliferation and reduce depigmentation by inhibiting autoimmunity. Inflammatory diseases such as psoriasis and acne can also benefit. The non-invasive nature and almost complete absence of side-effects encourages further testing in dermatology.

Read the full reasearch PMCID: PMC4126803

Prospective, Randomized Study on the Efficacy and Safety of Local UV-Free Blue Light Treatment of Eczema

Dermatology . 2016;232(4):496-502. doi: 10.1159/000448000. Epub 2016 Aug 19.


Background: Blue light was shown to reduce the activation of T cells and modulate cytokine release in vitro. Therefore, we investigated the efficacy of blue light in the treatment of eczema.

Methods: A sample of 21 patients with mild to moderate eczema were locally treated with blue LED light (light-emitting diode, emission maximum: 453 nm). They received light treatment 3 times per week for 4 weeks. A contralateral control lesion remained untreated.

Results: A total of 20 patients completed the trial with a compliance rate of 100%. The blue light treatment was safe with no adverse events and no side effects. The primary end point change from baseline in the mean sum score of the local Eczema Severity Index (local ESI) was more pronounced for the treated area than for the control area (-1.9 ± 2.02 vs. -1.3 ± 2.24). The treatment difference was statistically significant (p = 0.0152, paired t test, two-sided).

Conclusion: In this study, UV-free blue light was safe and effective in the reduction of eczema lesions.

Read the full reasearch PMID: 27537360

The Effects of 830 nm Light-Emitting Diode Therapy on Acute Herpes Zoster Ophthalmicus: A Pilot Study

Ann Dermatol . 2013 May;25(2):163-7. doi: 10.5021/ad.2013.25.2.163. Epub 2013 May 10.


Skin lesions and pain are the most distinctive features of herpes zoster. Light-emitting diode (LED) therapy is an effective treatment known for its wound-healing effects.

To determine whether the LED treatment affects wound healing and acute pain in acute herpes zoster ophthalmicus.

We recruited 28 consecutive Korean patients with acute herpes zoster ophthalmicus for the study. In the control group (group A), 14 subjects received oral famcyclovir. In the experimental group (group B), 14 subjects received oral famcyclovir and 830 nm LED phototherapy on days 0, 4, 7, and 10. In order to estimate the time for wound healing, we measured the duration from the vesicle formation to when the lesion crust fell off. The visual analogue scale (VAS) was used for the estimation of pain on days 4, 7, 10, and 14.

The mean time required for wound healing was 13.14±2.34 days in group B and 15.92±2.55 days in group A (p=0.006). From day 4, the mean VAS score showed a greater improvement in group B, compared with group A. A marginal but not statistically significant difference in the VAS scores was observed between the two groups (p=0.095).

LED treatment for acute herpes zoster ophthalmicus leads to faster wound healing and a lower pain score.


Read the full reasearch PMCID: PMC3662908
chrome firefox IE edge safari opera android appleinc