Where’s the scientific evidence?

If you’re a medical professional, you need evidence that there is science behind this technology and exactly how it works at the cellular level. Below is but only a sampling of the over 550 Randomized Clinical Trials that have been published using PBM devices, and the technology has been featured in over 4,000 laboratory studies. PBMT is used in thousands of clinics, hospitals and elite sports institutions in over 70 nations.

Over 700 RCT clinical trials

Over 4000 laboratory studies

Over 30 new research papers per month

Clinical Evidence – Sports Performance & Recovery

Photobiomodulation therapy (PBMT) reduces fatigue, accelerates recovery and improves performance.

Clinical Evidence:

  • Fatigue – reduced fatigue

  • Performance –  PBMT improves the VO2 kinetics in competitive cyclists

  • Recovery – recover faster

  • PBMT vs. Cryotherapy – PBMT is better than cryotherapy in muscle recovery after a high intensity exercise

  • Oxidative Stress – PBMT increases performance, decreases oxidative stress and reduces muscle damage after progressive running exercise.

  • Endurance – PBMT increases endurance for repeated elbow extension against resistance and decreased blood lactate, creatine kinase and C-reactive protein

  • Muscle Performance – PBMT increases torque in quadriceps muscle fatigue (Knee Extensor) study

  • Delayed Onset Muscle Soreness – PBMT reduces muscle soreness, increases strength, and reduces ROM impairment up to 96 hours after eccentric exercise.

PDF Digest

Clinical Evidence – Wellness

Photobiomodulation therapy (PBMT) has excellent wellness and beauty benefits. It doesn’t just leave clients looking younger, but also leaves them feeling more youthful.

Clinical Evidence:

  • Lean Muscle – increased lean muscle mass

  • Precondition – prophylactic preconditioning

  • Wrinkles – improve collagen and elastin production

  • Cardiometabolic Risk – PBMT with exercise decreased cardiometabolic risk factors in obese women (decreased circumferences, decreased fat, HOMA-IR, Leptin & ICAM)

  • Skin Complexion – PBMT improved skin complexion and skin feeling, profilometrically assessed skin roughness, and ultrasonographically measured collagen density

  • Cognitive Effects – transcranial PBMT produces beneficial cognitive and emotional effects in humans

  • Sleep – PBMT improves sleep, serum melatonin levels, and endurance performance of elite female basketball players

  • Blood Flow In The Brain – NovoTHOR PBMT increased oxygenated blood flow in the brain and increases Cytochrome C oxidase activity

  • Cognitive Performance – PBMT is as good as exercise in enhancing cognitive performance

PDF Digest

Clinical Evidence – Medicine

Photobiomodulation therapy (PBMT) is used in medicine for its ability to regenerate tissue, reduce inflammation, reduce edema and to induce an analgesic effect.

Clinical Evidence:

  • Injuries – regenerate tissue

  • Inflammation – reduce inflammation

  • Edema – reduce edema

  • Pain – induce analgesia

  • Back & Neck Pain – results from 23 RCTs show that PBMT can reduce pain, and improve function in radiculopathies as well as non-specific back and neck pain.

  • Osteoarthritis – results from 15 RCTs show that PBMT reduces pain, reduces inflammation, improves cartilage growth through stimulation of stem cells, and improves function in the TMJ, knee and finger joints.

  • Wound Healing – results from 12 RCTs show that PBMT can improve and speed the quality of healing of pressure sores, diabetic foot and leg ulcers.

  • Neuropathic Pain – results from 12 RCTs show that PBMT can reduce paresthesia, numbness and/or pain in DPN, CTS, PHN, shingles and trigeminal neuralgia.

  • Tendinopathies – data from 21 RCTs show PBMT reduces pain, inflammation, edema, better collagen fiber organization and improved function for shoulder, elbow and Achilles tendinopathies.

  • Brain – Results from human clinical trials show that PBMT can improve execution function, reduce depression and reduce vascular disease-related cognitive decline.

PDF Digest

What is Photobiomodulation Therapy & How Does It Work?

Photobiomodulation therapy (PBM Therapy) is the application of monochromatic light to improve the speed and quality of tissue repair.  It reduces inflammation, reduces edema and can induce analgesia.

The attached PDF shows what’s happening at the level of the mitochondria to reduce oxidative stress and boost ATP production in sick and damaged cells.  In stressed cells mitochondrial NO blocks respiration. Red & Near IR light dissociate NO from Cytochrome C Oxidase to restore cellular homeostasis. This is a dose-rate dependent effect that is well documented.

Biphasic dose response in PBMT – Harvard Medical School (2009)

This paper from Harvard Medical School reviews the LLLT mechanisms and the biphasic dose response. It summarises the molecular and cellular mechanisms of LLLT, gives a scientific explanation for the biphasic dose response (why a low dose has a stimulatory effect and why a high dose inhibits). Low power densities tend to get better healing and anti-inflammatory effects where higher power densities are more likely to inhibit (which may be useful if you just want an analgesic effect).  James Carroll CEO THOR Photomedicine is a co-author on this paper.

Update paper in 2011 on PubMed

Mechanisms of Low Level Light Therapy (LLLT or PBMT) – Harvard Medical School

Michael R. Hamblin

Department of Dermatology, Harvard Medical School, BAR 414
Wellman Center for Photomedicine, Massachusetts General Hospital
40 Blossom Street, Boston MA 02114

The use of low levels of visible or near-infrared (NIR) light for reducing pain, inflammation and edema, promoting healing of wounds, deeper tissues and nerves, and preventing tissue damage has been known for almost forty years since the invention of lasers. Originally thought to be a peculiar property of laser light (soft or cold lasers), the subject has now broadened to include photobiomodulation and photobiostimulation using non-coherent light. Despite many reports of positive findings from experiments conducted in vitro, in animal models and in randomized controlled clinical trials, LLLT remains controversial. This likely is due to two main reasons; firstly, the biochemical mechanisms underlying the positive effects are incompletely understood, and secondly, the complexity of rationally choosing amongst a large number of illumination parameters such as wavelength, fluence, power density, pulse structure and treatment timing has led to the publication of a number of negative studies as well as many positive ones. In particular, a biphasic dose response has been frequently observed where low levels of light have a much better effect than higher levels.

This introductory review will cover some of the proposed cellular chromophores responsible for the effect of visible light on mammalian cells, including cytochrome c oxidase (with absorption peaks in the NIR), and photoactive porphyrins. Mitochondria are thought to be a likely site for the initial effects of light, leading to increased ATP production, modulation of reactive oxygen species, and induction of transcription factors. These effects in turn lead to increased cell proliferation and migration (particularly by fibroblasts), modulation in levels of cytokines, growth factors and inflammatory mediators, and increased tissue oxygenation. The results of these biochemical and cellular changes in animals and patients include such benefits as increased healing of chronic wounds, improvements in sports injuries and carpal tunnel syndrome, pain reduction in arthritis and neuropathies, and amelioration of damage after heart attacks, stroke, nerve injury, and retinal toxicity.

Full Article

PBMT for Pain Research Digest

Extensive research has been done on how PBMT can control and block pain signals, allowing for accelerated healing and immediate pain relief without medication.  Topics include:

  • Back & neck pain

  • Neuropathic pain

  • Tendinopathies

  • Postoperative pain

  • Anti-inflammatory mechanisms of PBMT

  • Analgesic action of PBMT

Wound Healing Research Digest

  • Diabetic leg ulcers

  • Venous leg ulcers

  • Pressure ulcers

  • Acute wounds

  • Meta-analysis

  • Inverclyde Royal Hospital review of pressure sore and venous ulcer patients.

PDF Digest

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

J Biophotonics. 2016 Dec; 9(11-12): 1273–1299.

Cleber Ferraresi,1,2,3 Ying-Ying Huang,1,2 and Michael R. Hamblin1,2,4

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.

PubMed Full Article

Sports Fatigue & Recovery Research Digest

PBMT is well documented to enhance performance, reduce fatigue & reduced recovery times (24 hours or less) after exertion.  Topics include:

  • PBMT improves fatigue in competitive cyclists

  • PBMT in the NovoTHOR is superior to Cryotherapy

  • Muscle damage markers if PBMT is before or after exercise

  • Pre-exercise PBMT

  • PBMT or muscle strength in elderly women

  • Lactate levels in acute heart failure after PBMT

  • Restoring locomotor function after ischemic stroke

  • PBMT before matches leads to reduced creatine kinase in volleyball players

  • Muscular pre-conditioning with PBMT before intense exercise

  • Attenuation of strength loss after strenuous resistence exercise

  • And many more…

PDF Digest

Sports/Common Injuries Research Digest

Here is a digest of the most common sports-related injuries and PBMT’s role in increasing healing and recovery time.  Topics include:

  • Chronic shoulder pain

  • Chronic low back pain

  • Lumbar disk herniation

  • Dorsal root ganglion treatment for low back pain

  • Carpal tunnel syndrome (CTS)

  • Chronic neck pain

  • Achilles Tendinopathy

  • Knee arthritis

  • Post-mastectomy pain syndrome

  • Temporomandibular disorders

  • Frozen shoulder

  • Tendinopathies

  • Tinnitis due to sensorineural hearing loss

  • Ulnar neuropathy’

  • Myofacial pain syndrome of the trapezius

  • Post-operative tibial fracture repair

  • Dentin hypersensitivity

  • Hand & wrist fractures

  • Periostitis of the lower leg (shin splints in runners)

  • Whiplash injuries

  • Myofacial trigger point deactivation vs. 2% lidocaine injection (PBMT as good as lidocaine)

  • Appearance of cellulite

  • And many more…

PDF Digest

Dental Research Digest

  • Developments in LLLT for dentistry


  • Myofacial pain syndrome

  • Orofacial and maxillofacial region pain

  • Persistent idiopathic facial pain (PIFP)

  • Neurogenic facial pain

  • Trigeminal neuralgia

  • Oral lichen planus

  • Recurrent aphthous ulcers

  • Post-operative pain

  • Rate of tooth movement

  • Acute Herpes Zoster Ophthalmicus

  • Orthodontics and pain management

  • Oral pemphigus vulgaris

  • Pediatric dentistry

  • Xerostomia

  • Stevens-Johnson Syndrome

  • Burning mouth syndrome

  • Hand-foot-and-mouth disease stomatitis

PDF Digest

Shining light on the head: Photobiomodulation for brain disorders – Harvard Medical School (2016)

BBA Clin. 2016 Dec; 6: 113–124.

Michael R. Hamblin

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. In this transcranial PBM (tPBM) application, near-infrared (NIR) light is often applied to the forehead because of the better penetration (no hair, longer wavelength). Some workers have used lasers, but recently the introduction of inexpensive light emitting diode (LED) arrays has allowed the development of light emitting helmets or “brain caps”. This review will cover the mechanisms of action of photobiomodulation to the brain, and summarize some of the key pre-clinical studies and clinical trials that have been undertaken for diverse brain disorders.

PubMed Full Article

Traumatic Brain Injury & Stroke

Dr. Margaret Naeser at Boston University HospitalDr. Michael Hamblin at Harvard Medical School and their colleagues continue to do groundbreaking research on the use PBM Therapy on Traumatic Brain Injuries (including stroke) as well as cognitive dysfunction and dementia. The results they are seeing are exceptional and have exciting implications for the future of medicine and the treatment of conditions and diseases that have not had encouraging treatment options, until now.

Significant improvements in cognitive performance post-transcranial, red/near-infrared light-emitting diode treatments in chronic, mild traumatic brain injury: open-protocol study.

Naeser MA, Zafonte R, Krengel MH, Martin PI, Frazier J, Hamblin MR, Knight JA, Meehan WP 3rd, Baker EH., J Neurotrauma. 2014; 31(11):1008-17


This pilot, open-protocol study examined whether scalp application of red and near-infrared (NIR) light-emitting diodes (LED) could improve cognition in patients with chronic, mild traumatic brain injury (mTBI). Application of red/NIR light improves mitochondrial function (especially in hypoxic/compromised cells) promoting increased adenosine triphosphate (ATP) important for cellular metabolism. Nitric oxide is released locally, increasing regional cerebral blood flow. LED therapy is noninvasive, painless, and non-thermal (cleared by the United States Food and Drug Administration [FDA], an insignificant risk device). Eleven chronic, mTBI participants (26-62 years of age, 6 males) with nonpenetrating brain injury and persistent cognitive dysfunction were treated for 18 outpatient sessions (Monday, Wednesday, Friday, for 6 weeks), starting at 10 months to 8 years post- mTBI (motor vehicle accident [MVA] or sports-related; and one participant, improvised explosive device [IED] blast injury). Four had a history of multiple concussions. Each LED cluster head (5.35 cm diameter, 500mW, 22.2mW/cm(2)) was applied for 10min to each of 11 scalp placements (13J/cm(2)). LEDs were placed on the midline from front-to-back hairline; and bilaterally on frontal, parietal, and temporal areas. Neuropsychological testing was performed pre-LED, and at 1 week, and 1 and 2 months after the 18th treatment. A significant linear trend was observed for the effect of LED treatment over time for the Stroop test for Executive Function, Trial 3 inhibition (p=0.004); Stroop, Trial 4 inhibition switching (p=0.003); California Verbal Learning Test (CVLT)-II, Total Trials 1-5 (p=0.003); and CVLT-II, Long Delay Free Recall (p=0.006). Participants reported improved sleep, and fewer post-traumatic stress disorder (PTSD) symptoms, if present.

Participants and family reported better ability to perform social, interpersonal, and occupational functions. This open-protocol data suggest that placebo-controlled studies are warranted.

Cognitive Dysfunction or Dementia

Significant Improvement in Cognition in Mild to Moderately Severe Dementia Cases Treated with Transcranial Plus Intranasal Photobiomodulation: Case Series Report.
Saltmarche AE1, Naeser MA2,3, Ho KF4, Hamblin MR5,6, Lim L7., Photomed Laser Surg. 2017 Feb 10. doi: 10.1089/pho.2016.4227


This study investigated whether patients with mild to moderately severe dementia or possible Alzheimer’s disease (AD) with Mini-Mental State Exam (MMSE) Baseline scores of 10-24 would improve when treated with near-infrared photobiomodulation (PBM) therapy.

Animal studies have presented the potential of PBM for AD. Dysregulation of the brain’s default mode network (DMN) has been associated with AD, presenting the DMN as an identifiable target for PBM.

The study used 810 nm, 10 Hz pulsed, light-emitting diode devices combining transcranial plus intranasal PBM to treat the cortical nodes of the DMN (bilateral mesial prefrontal cortex, precuneus/posterior cingulate cortex, angular gyrus, and hippocampus). Five patients with mild to moderately severe cognitive impairment were entered into 12 weeks of active treatment as well as a follow-up no-treatment, 4-week period. Patients were assessed with the MMSE and Alzheimer’s Disease Assessment Scale (ADAS-cog) tests. The protocol involved weekly, in-clinic use of a transcranial-intranasal PBM device; and daily at-home use of an intranasal-only device.

There was significant improvement after 12 weeks of PBM (MMSE, p < 0.003; ADAS-cog, p < 0.023). Increased function, better sleep, fewer angry outbursts, less anxiety, and wandering were reported post-PBM. There were no negative side effects. Precipitous declines were observed during the follow-up no-treatment, 4-week period. This is the first completed PBM case series to report significant, cognitive improvement in mild to moderately severe dementia and possible AD cases.

Results suggest that larger, controlled studies are warranted. PBM shows potential for home treatment of patients with dementia and AD.

PubMed Full Article

Low Level Light Therapy of the Eye & Brain

Julio C Rojas1,2, F Gonzalez-Lima1
1Departments of Psychology, Pharmacology and Toxicology, University of Texas at Austin, Austin, TX; 2Department of Neurology and Neurotherapeutics, University of Texas Southwestern Medical Center, Dallas, TX, USA


Low-level light therapy (LLLT) using red to near-infrared light energy has gained attention in recent years as a new scientific approach with therapeutic applications in ophthalmology, neurology, and psychiatry. The ongoing therapeutic revolution spearheaded by LLLT is largely propelled by progress in the basic science fields of photobiology and bioenergetics. This paper describes the mechanisms of action of LLLT at the molecular, cellular, and nervous tissue levels. Photoneuromodulation of cytochrome oxidase activity is the most important primary mechanism of action of LLLT. Cytochrome oxidase is the primary photoacceptor of light in the red to near-infrared region of the electromagnetic spectrum. It is also a key mitochondrial enzyme for cellular bioenergetics, especially for nerve cells in the retina and the brain. Evidence shows that LLLT can secondarily enhance neural metabolism by regulating mitochondrial function, intraneuronal signaling systems, and redox states. Current knowledge about LLLT dosimetry relevant for its hormetic effects on nervous tissue, including noninvasive in vivo retinal and transcranial effects, is also presented. Recent research is reviewed that supports LLLT potential benefits in retinal disease, stroke, neurotrauma, neurodegeneration, and memory and mood disorders. Since mitochondrial dysfunction plays a key role in neurodegeneration, LLLT has potential significant applications against retinal and brain damage by counteracting the consequences of mitochondrial failure. Upon transcranial delivery in vivo, LLLT induces brain metabolic and antioxidant beneficial effects, as measured by increases in cytochrome oxidase and superoxide dismutase activities. Increases in cerebral blood flow and cognitive functions induced by LLLT have also been observed in humans. Importantly, LLLT given at energy densities that exert beneficial effects does not induce adverse effects. This highlights the value of LLLT as a novel paradigm to treat visual, neurological, and psychological conditions, and supports that neuronal energy metabolism could constitute a major target for neurotherapeutics of the eye and brain.


LLLT or photobiomodulation refers to the use of low-power and high-fluence light from lasers or LEDs in the red to near-infrared wavelengths to modulate a biological function. Cytochrome oxidase is the primary photoacceptor of LLLT with beneficial eye and brain effects since this mitochondrial enzyme is crucial for oxidative energy metabolism, and neurons depend on cytochrome oxidase to produce their metabolic energy. Photon-induced redox mechanisms in cytochrome oxidase cause other primary and secondary hormetic responses in neurons that may be beneficial for neurotherapeutic purposes. Beneficial in vivo effects of LLLT on the eye have been found in optic nerve trauma, methanol intoxication, optic neuropathy, retinal injury, retinitis pigmentosa, phototoxicity, and age-related macular degeneration. Beneficial in vivo transcranial effects of LLLT on the brain have been observed in anoxic brain injury, atherothrombotic stroke, embolic stroke, ischemic stroke, acute traumatic brain injury, chronic traumatic brain injury, neurodegeneration, age-related memory loss, and cognitive and mood disorders. No adverse side effects have been reported in these beneficial applications of LLLT in animals and humans. The authors conclude that LLLT is a safe and beneficial approach, based on scientifically sound mechanisms of action of red to near-infrared light on cytochrome oxidase, with neurotherapeutic promise for a wide range of ophthalmological, neurological, and psychological conditions.

PubMed Full Article