Referenced in The New Zealand Journal of Natural Medicine issue 48, May 2023.
The Wondrous Healing Capacity of Red and Near-infrared Light
Red and near-infrared light have been shown in studies for decades to have incredible regenerative effects on the body. Early studies were carried out with lasers, but subsequently LED lights were discovered to also be therapeutic. To encompass this new finding the initialism LLLT was changed from meaning low-level laser therapy to low-level light therapy; now more commonly referred to as photobiomodulation (PBM). LED lights are inexpensive, easier to use than lasers and require no specialist medical training. They can safely be used from the comfort of one’s own home. These non-ionising, non-thermal LED lights penetrate from around 610 nanometres (nm) to 750 nm in the red range and 750 nm to 1300 nm in the near-infrared range (NIR). The former treats skin issues; the latter is better for deeper problems.
Infrared lamps are currently only generally marketed for reducing pain and inflammation. Inflammation is a natural part of healing, but chronic inflammation is associated with many conditions including Alzheimer’s, asthma, cancer, heart disease, arthritis and diabetes. The effects reach way beyond pain and inflammation. PBM up-regulates antioxidant defences and reduces oxidative stress; preserves, stimulates and regenerates cells; speeds up tissue and bone repair and can even be the impetus to form new neurons (neurogenesis) and synapses (synaptogenesis) in the brain, giving hope to those with traumatic brain injury (TBI), dementia and Parkinson’s disease (PD) sufferers where previously there’s been no effective treatment.
To date there are over 6000 studies on PBM.
Red and infrared light don’t emit heat per se; it is the actual light photons that stimulate changes, but some lamps are made to emit high levels of heat, which may have a separate biological effect to the light and possibly induce thermal damage. Such lamps are unsuitable for diabetics and usually display a warning. Infrared light however is beneficial for diabetics as it helps foot ulcers resistant to conventional treatment heal and thus prevents serious complications such as amputations. [1]
Infrared light is invisible, although some lamps colour the bulbs red to emit a red light, so you can see it’s working. Others don’t, so no light can be seen.
“The medical benefits of low level laser therapy (LLLT) were first discovered in 1967 by Dr. Endre Mester at the Semmelweis Medical University in Hungary. Mester was trying to repeat an experiment originally described by McGuff in Boston USA, who had successfully used a ruby laser to cure malignant tumors in rats. However, Mester’s laser possessed only a very small fraction of the power possessed by McGuff’s laser. Thus he was unsuccessful in curing any tumors. However, he did observe a heightened rate of hair growth and better wound healing in the rats in which he had surgically implanted tumors, the first indication that low level laser light (rather than high power thermal lasers) could have its own distinct applications in medicine. [2]
“In 1993, Quantum Devices developed a light-emitting diode for NASA to use in their plant growth experiments. The experiments demonstrated that red LED wavelengths could boost plant growth, but coincidentally the scientist’s skin lesions began to heal faster as well. NASA subsequently began to study the use of LED to increase the metabolism of human cells and stem the loss of bone and muscle in astronauts.” [3]
The effective dose of PBM appears to follow the principle of hormesis, which is when the body benefits from short-term stressors much in the same way exercise, fasting, heat and cold exposure work. Its mild stressing effects make the body more resilient. There’s a biphasic dose response whereby once a certain level is reached stimulatory effects are observed, whilst higher doses are less effective or not effective at all. You can think of this in terms of a bell curve with the peak of the bell being the effective dose and any lower or higher doses being less or ineffective.
All the exact mechanisms of action are unknown. The absorption of light triggers a complex and highly-debated cascade of signaling pathways leading to activation of transcription factors and changes in protein expression that can positively affect almost every physiological function.
It is widely accepted, but somewhat disputed in recent years that the light is absorbed via the primary chromophore cytochrome c oxidase and calcium ion channels. [4] PBM in turn directly affects the mitochondria, which are akin to the powerhouse of our cells, to produce more adenosine triphosphate (ATP), which is akin to the energy of our cells. In unhealthy mitochondria excessive nitric oxide (NO) binds to cytochrome c and competes with oxygen leading to lower levels of ATP being produced. PBM reverses this. NO is a powerful vasodilator. Its release dilates blood vessels leading to greater blood flow. [5]
It has been found that PBM can produce reactive oxygen species (ROS) in normal cells, but when used in oxidatively stressed cells ROS levels are lowered, i.e. too little or too much ROS in certain states can be harmful and PBM balances this out. [6]
“…the beneficial effects of transcranial photobiomodulation (tPBM) on the brain can be explained by increases in cerebral blood flow, greater oxygen availability and oxygen consumption, improved ATP production and mitochondrial activity. However there are many reports that a brief exposure to light (especially in the case of experimental animals that have suffered some kind of acute injury or traumatic insult) can have effects lasting days, weeks or even months. This long-lasting effect of light can only be explained by activation of signaling pathways and transcription factors that cause changes in protein expression that last for some considerable time. The effects of PBM on stimulating mitochondrial activity and blood flow is of itself, unlikely to explain long-lasting effects. A recent review listed no less than fourteen different transcription factors and signaling mediators, that have been reported to be activated after light exposure.” [5]
“More than 500 genes showed altered brain expression as a result of remote PBM pre-conditioning; a number of these clustered into molecular pathways that could provide clues to the mechanisms of action. One prime example was enrichment of pathways related to stem cell signalling, which other investigators have proposed as a mechanism underlying the systemic effects of remote PBM.” [7]
“Although it remains to be determined whether bone marrow-derived stem cells are involved in remote PBM-induced neuroprotection, cell populations such as mesenchymal stem cells, which reside in the bone marrow and other tissues, are strong candidates. As reviewed elsewhere, a small proportion of mesenchymal stem cells can cross the blood-brain barrier, home specifically to areas of tissue damage and release a range of trophic factors that enhance cell protection and repair.” [7]
“It is becoming increasingly clear that stem cells are highly responsive to light, compared to other types of somatic cells. Stem cells have the capacity for long-term self-renewal without senescence and the ability to differentiate into one or more specialized cell types thus providing an inexhaustible supply of cells for tissue repair.” [8]
“…light delivered to the bone marrow can mobilize stem cells into the circulation where they become progenitor cells and are exposed to diverse cues in the bloodstream instructing them where to travel to in order to repair tissue that is damaged or at risk of dying.” [8]
The ex Australian MP Max Burr who suffers from PD heard about the protective effect of red and infrared light on neuron cells in mice from an ex doctor friend and wondered if it could help him. Upon contacting the professor who conducted the mice study he was told a large human trial could be ten years away. Feeling he didn’t have time to wait he decided to try it anyway. He made his own light helmet by sourcing a red LED light strip and placing it inside a bucket, of all things. He proceeded to wear it twice daily for three years whilst doctors monitored his progress. The results were that he had significant improvement in nine out of ten of his symptoms, including regaining his sense of smell and fine motor movements, enabling him to play the piano again. The only symptom that didn’t improve was muscle stiffness. Max is quoted as saying at best it can protect against further deterioration, but it does appear that it’s improved most of his symptoms. [9,10,11]
“In light of the predicted doubling in the number of people affected by dementia and Alzheimer’s disease within the next 30 years, a treatment option which has already shown promising results in cell culture studies and animal models, and whose safety has already been proven in humans, must not be left in the dark.” [12]
To date there’s been 13 studies on 1-65 humans that show infrared has a positive impact on Alzheimer’s disease without harmful effects. It is a general finding that mitochondrial dysfunction, inadequate supplies of ATP, and oxidative stress are contributory factors in almost all forms of brain disease. [13]
You’d be forgiven for thinking the longest wavelength would cover everything, but it’s not as simple as that. Light in the 700–750 nm range, for example, tends to have little impact, whereas the impact of light in the 600–690 nm is far greater. [2]
Another study found when comparing 660 nm, 808 nm, and 940 nm light on human cadaver heads that 808 nm penetrated the deepest, reaching a depth in the brain of 40–50 mm. [14]
Comparisons of studies are difficult due to the bewildering array of different wavelengths; power densities (mW/cm2), which equals the power of the light source in watts divided by the area over which the light hits the body; energy density (sometimes called the fluence), which is provided by Joules/area (J/cm2); number of repetitions, duration of treatment, and the mode of light delivery (continuous or pulsed). Also the exact parameters are not always properly recorded in studies.
PD manifests after a major degeneration of neurones mainly within the brainstem. PBM at best penetrates 20-30 mm into the body. It doesn’t penetrate deeply enough to reach the brainstem (80-100 mm), but it may not matter.
” Photobiomodulation may influence the neuronal function and survival in the brainstem through an indirect stimulation, using a “middle-man” in the circulation (e.g., immune cells), and/or by activating motor cortex and other neural circuits which have components closer to the brain surface.” [15]
“…when PBM is used to target a specific area other than the brain, such as lower back pain, the brain can benefit remotely from the changes being caused. For example, PBM stimulates macrophages and mast cells, which can benefit the brain. Also, regardless of the treatment site, PBM can lead to the down-regulation of pro-inflammatory cytokines and the up-regulation of anti-inflammatory cytokines on a body-wide basis, meaning that the brain will still benefit from the positive effects despite not being the specific target for treatment. Another possibility is that PBM can trigger the production of a yet-unidentified extracellular signaling molecule from the mitochondria (for instance), which is then transported to enable the remote action of PBM on brain cells and other non-local cells.” [16]
It was even shown to improve Alzheimer’s in mice when NIR light was delivered to their tibia (shinbone). It’s theorised this occurred as stems cells in bone marrow were stimulated and led to the brain being infiltrated and β-amyloid plaques indicative of Alzheimer’s being cleared. This suggests a more systemic effect of PBM rather than just localised. [16]
In the case of traumatic brain injury (TBI) PBM has been shown to “…stimulate healing, protect tissue from dying, increase mitochondrial function, improve blood flow and tissue oxygenation. PBM can also act to reduce swelling, increase antioxidants, decrease inflammation, protect against apoptosis (cell suicide), and modulate microglial activation state” [17] (activated microglial immune cells are a marker of neuron damage) [18]
PBM also helps the brain repair itself by the formation of new neurons in the brain (neurogenesis) and synapses (synaptogenesis) – the points of contact where information is transmitted between neurons.
“Functional magnetic resonance imaging has shown modulation of activation in intrinsic brain networks likely to be damaged in TBI.” [17]
Some mild conditions are fully cured after short-term treatment; other chronic conditions such as Alzheimer’s require long-term treatment, as benefits are lost upon cessation. Benefits can even be attained if treatment begins years after condition onset.
For example, mild TBI 7 years prior to PBM treatment resulted in a patient improving focus time from 20 minutes to 3 hours after 8 weeks of treatment. Another patient who was on medical disability returned to full-time work after 4 months of treatment. Both patients experienced regression when treatment stopped for only a week or two, so they are continuing treatment. [19]
This study showed 11 people with TBI had positive outcomes. [20]
“From age 20 to 60, cerebral blood flow (CBF) is estimated to dip about 16% and continues to drop at a rate of 0.4%/year. This CBF dip will slowly reduce oxygen/glucose delivery to the brain thus lowering ATP energy production needed by brain cells to perform normal activities. Reduced ATP production from mitochondrial loss or damage in the wear-and-tear of aging worsens when vascular risk factors (VRF) to Alzheimer’s disease develop that can accelerate both age-decline CBF and mitochondrial deficiency to a level where mild cognitive impairment (MCI) develops. To date, no pharmacological or any other treatment has been successful in reversing, stabilizing or delaying MCI. For the first time in medical interventions, a non-pharmacological, non-invasive, well-tolerated, easy to perform, free of significant side effects and cost-effective treatment may achieve what virtually all AD treatments in the past have been unable to accomplish.” [21]
“… trials of pharmaceutical drugs to treat brain damage due to stroke or TBI have largely been unsuccessful. Moreover, despite huge amounts of funding and research by both academic labs and industry, progress in discovering drugs to halt Alzheimer’s and Parkinson’s diseases has not been dramatic. Perhaps it is time to give tPBM serious trials for these indications considering its established safety and notable lack of adverse effects, and relative cost-effective nature?” [22]
“The mainstay of pharmaceutical treatment for pain in Musculoskeletal Disorders (MSDs) and Osteoarthritis (OA) has been nonsteroidal anti-inflammatory drugs (NSAIDs).” In 2004 the NSAID Vioxx was pulled from the market by Merck amid lawsuits and implicated in causing between 88,000 and 139,000 heart attacks, 30–40% of which were fatal. The total settlement costs were in excess of $5 billion. The so-called “Vioxx scandal” has tainted the whole subject of NSAIDs as therapeutic agents.”
“The growing reluctance to prescribe NSAIDs has recently led to a corresponding growing tendency to prescribe opioid painkillers instead. However, as it is now well known that there is a growing epidemic of deaths due to opioid overdoses, many of which started off with patients receiving legally prescribed opiate medications for painful conditions including MSDs/OA.” [23]
“For humans, clinical trials are needed, and costs are always limiting factors for execution of human clinical trials. PBM has been disadvantaged by the fact that companies in the PBM field have only a tiny fraction of the resources that are available to large pharmaceutical companies who can spend millions of dollars on large clinical trials.” [23]
“The cost of formal clinical trials has held back the PBM field. Even if formal designs for clinical protocols have greatly improved, funds to carry out the studies have often not been made available due to prejudices and negative bias from the past.”
“Pain is a symptom; while the goal of analgesics has been to mute the symptom, the greater potential of PBM for treating MSDs/OA resides in its capability for tissues healing.” [23]
A lamp held 20 cm away will cover a larger area than 10 cm distance, but as penetration is exponentially increased the nearer it’s held, it’s advisable to get a lamp large enough to cover the required area at 10 cm away.
On the brain: “Results showed an exponential increase in fluence rate with a linear decrease in distance between measurement probe and light source.” [24]
PBM “has been increasingly used for the treatment of toxicities related to cancer treatment. One of the challenges for the universal acceptance of PBMT use in cancer patients is whether or not there is a potential for the light to stimulate the growth of residual malignant cells that evaded oncologic treatment, increasing the risk for tumor recurrences and development of a second primary tumor. Current science suggests promising effects of PBMT in the prevention and treatment of breast cancer-related lymphedema and oral mucositis, among other cancer treatment toxicities. Nevertheless, this seems to be the first systematic review to analyze the safety of the use of PBMT for the management of cancer-related toxicities. Scopus, MEDLINE/PubMed, and Embase were searched electronically. A total of 27 articles met the search criteria. Selected studies included the use of PBMT for prevention and treatment of oral mucositis, lymphedema, radiodermatitis, and peripheral neuropathy. Most studies showed that no side effects were observed with the use of PBMT. The results of this systematic review, based on current literature, suggest that the use of PBMT in the prevention and management of cancer treatment toxicities does not lead to the development of tumor safety issues.” [25]
“PBM has been used for >50 years, and no serious side effects have been reported. In a decade when side effects of pharmaceuticals are alarming and antibiotic resistance is a threat, this treatment modality appears to be much needed in the medical armamentarium, but first the scientific strength needs to be increased, and this can only occur if the basic use and reporting of light parameters are improved.” [26]
There’s clearly a whole wealth of research on the benefits of red and infrared light. Using an electrical device is an unnatural state of affairs, so where does this light occur in nature? The sun! The experts only ever talk about the sun in terms of UV light effects, but at ground-level this only represents 3% of the spectrum; 44% is visible light and the remaining 53% is infrared.
Although these levels will be much lower than those emitted by an electrical device, it’s another reason that completely shunning the sun may be harmful. Perhaps diseases and conditions that the lamps treat can be prevented by adequate, sensible infrared exposure from the sun. Lower levels of sunlight exposure are associated with higher levels of dementia. Although low levels of vitamin D have been associated with increased dementia risk and supplementation has sometimes been shown to reduce the risk, lower sunlight exposure will also mean lower infrared exposure, which may be another risk factor. [27]
Even wearing a hat at all times may prevent benefits, as regular low-levels of the sun’s infrared light on the forehead (the light doesn’t penetrate hair well) may be beneficial. This isn’t scientifically proven; it’s just conjecture on my part. After all, although infrared light has been shown to have a systemic effect, i.e. positively affecting the brain when shone on another area, it works better if targeted directly to the head. Given that most of us are lacking in sun exposure we’d maybe benefit from regular use of an infrared lamp to maintain good health.
Perhaps it’s time to stop inducing injuries and diseases in animals to test upon them when the lights have been shown to be very safe in humans. [28] Considering the vast array of conditions PBM is therapeutic for; that it was discovered in 1967 and there have been virtually no harmful effects reported, the delay in large human trials is somewhat scandalous. Dementia alone affects 50 million people worldwide. Rather than wait for trials that may never come it’s perhaps prudent to spread the word and purchase one of these relatively inexpensive lights and begin treatment at home starting with a low dose of just five minutes a day for illness/injury or once a week for health maintenance and seeing how you get on. Lamps with a combination of 660 nm and 850 nm are widely available (these frequencies have been extensively studied). No harmful effects have been observed. Bear in mind some companies don’t divulge the products’ frequencies, as they consider it proprietary information. Improvements should be seen within a month and often much sooner; sometimes noticeable after only one treatment. Stop using on a targeted area when desired results are attained unless it’s a chronic condition, which may require long-term treatment.
This article merely touches upon some of PBM’s more serious applications. See link for the full list of studies, which is constantly expanding. Find the condition of interest on the left side and corresponding scientific studies on the right side. [29]
[1] https://www.ijsurgery.com/index.php/isj/article/view/4172
[2] Introduction, second/third paragraph: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5448311
[3] Background, second paragraph: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4272231
[4] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6462613
[5] 2.2/2.4: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5066074
[6] https://pubmed.ncbi.nlm.nih.gov/28748217
[7] Eighth paragraph: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6788247
[8] Tenth paragraph: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5995606
[9] https://www.facebook.com/breakfastnews/videos/379553426196026
[11] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4707222
[12] Abstract: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7369090
[13] 3.1: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6664299
[14] 3.1: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5066074
[15] Penultimate paragraph: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6128061
[16] 3.2: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5448311
[17] Abstract: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5803455
[18] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2951017
[19] Abstract: https://www.ncbi.nlm.nih.gov/labs/pmc/articles/PMC3104287
[20] https://pubmed.ncbi.nlm.nih.gov/24568233
[21] https://pubmed.ncbi.nlm.nih.gov/31704275
[22] 11: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5448311
[23] Pharmacological treatment of MSDs/OA and the problem with drugs:
Initiative to reduce cost of clinical research on humans:
Key area of improvements for translational research into physical rehabilitation practice:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6648198
[24] Transmission: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7369090
[25] https://pubmed.ncbi.nlm.nih.gov/31109692
[26] Last paragraph: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4799704
[27] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9036798
[28] 3.5: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5066074
[29] https://docs.google.com/spreadsheets/d/1ZKl5Me4XwPj4YgJCBes3VSCJjiVO4XI0tIR0rbMBj08