Infrared light is a range of electromagnetic radiation that some commercially-available devices create. Manufacturers and proponents pinned a lot of claims of these devices – from saying infrared light reduces inflammation and pain to claiming it improves mood. Do any of these purported benefits hold up to the science? Read on to find out.
What is Infrared Light?
How much do we know?
Infrared radiation (IR), or infrared light, is a form of electromagnetic radiation that’s become popular with widely available infrared light devices. These devices can be lasers, lamps, or tanning bed-like machines. However, this technique is still controversial as a therapeutic approach.
Some manufacturers claim these devices will help people lose weight, reduce inflammation, relieve pain, and even improve mood. Is there any substance to the hype? Very little and not enough to draw any health-related conclusions.
FDA Status & Safety Research
Infrared light therapy or red light therapy has not been approved by the FDA for any medical purpose or health claim. Talk to your doctor before using an infrared sauna or device.
Infrared research in the US began in the late 1970s. In the mid ‘80s, the FDA reviewed the effects of an infrared laser on rheumatoid arthritis and concluded that there is insufficient safety data to approve the device [1].
Specifically, the laser didn’t pass so-called premarket approval (PMA), which is the FDA process of scientific and regulatory review that evaluates the safety and effectiveness of devices [2].
Although about 22 devices currently have FDA approval, experts point out that this is due to looser regulations since 2001. According to the new 510K process, devices can be approved as “adjunct in the treatment of pain” as long as they are similar enough – that is, at last as safe and effective – to already cleared IR devices on the market [1].
Scientists and regulatory bodies agree that the clinical benefits of IR have yet to be established [1].
Wavelength Range
Infrared light is outside the visual spectrum. It gets its name from the fact that it lies just beyond the wavelength of red light. It is often categorized as near-infrared (NIR), infrared (IR), and far-infrared (FIR) radiation [3].
NIR wavelength ranges from 700 – 810 nanometers (nm), IR wavelength ranges from 810 – 3000 nm, and FIR ranges from 3000 – 100,000 nm [3].
Proponents of infrared saunas and other methods of IR delivery say that these differences in wavelength cause infrared radiation to have a range of effects. However, their claims remain unproven.
According to limited research, IR has the ability to penetrate human tissue. The wavelength with the greatest ability to penetrate tissue likely lies between 690 and 900 nanometers [3].
Types of Devices
Commercially-available lamps are designed to emit radiation above 700 nm. Some lamps can also emit specific ranges within the IR spectrum, though these are less common due to their high cost [4].
Infrared saunas and smaller infrared devices use these lamps as well as infrared lasers to deliver infrared light to the entire surface of the body or to specific areas.
Far-infrared saunas (FIRSs) are approved by the FDA and Canadian Standards Association and are sold to the public as recreational saunas.
Infrared-radiation-emitting substances can be incorporated into fabrics or devices for continuous delivery [5, 4].
For example, some companies market infrared body wraps, which are made of large silicone bandages or pads that emit infrared light around the legs, stomach, and arms. Infrared wraps are promoted for “reducing cellulite” and “fat loss,” though none of these effects have been proven.
Mechanisms of Action
As opposed to ionizing radiation like far-ultraviolet radiation and x-rays, infrared light is a non-ionizing form of radiation. According to limited research, there is no evidence that infrared radiation damages DNA, though no long-term safety studies are available [6].
Some scientists are researching if infrared light can reduce cell damage associated with ionizing radiation [6].
Other researchers hypothesize that infrared radiation has unique mechanisms in interacting with biological tissue. The first major effect is increasing the temperature of the target tissue. Most infrared radiation sources also radiate a large amount of heat, which can affect a specific region. This has a similar effect to using a simple hot compress [7, 7].
The second major category of interaction infrared radiation can have is non-heating, which generally involves infrared radiation being absorbed by the bonds of specific molecules or structures within the body. The structure is then excited, activated, or changes shape as a direct result [8].
Finally, infrared light is being investigated for activating biomedical devices (such as biopolymers) to release a drug or substance to a targeted area or interact with the tissue [9].
Potential Health Benefits
The following purported benefits are only supported by limited clinical studies with small sample sizes, moderate-to-high risk of bias, low quality, and short duration. The general consensus is that better designed, controlled, and powered studies are needed.
Therefore, there is insufficient evidence to support the use of infrared light for most of the below-listed uses.
Additionally, remember that infrared saunas and devices have not been approved by the FDA for any medical purpose.
Talk to your doctor before using infrared light as part of a complementary health management strategy. Infrared light should never be used as a replacement for approved medical therapies.
Possibly Effective for:
1) Psoriasis
Some clinical evidence backs up the use of infrared light therapy for psoriatic skin changes.
Although clinical trials of low-level light/laser therapy (LLLT) are still small, near infrared (NIR) and visible red light with low energy show promise for psoriasis due to their strong skin penetration [10].
Photodynamic therapy with intense pulsed light is different from infrared light. It is used for nail psoriasis.
Insufficient Evidence for:
The following purported benefits are only supported by limited, low-quality clinical studies. There is insufficient evidence to support the use of red light therapy for any of the below listed uses. Never use red light therapy in place of something your doctor recommends or prescribes.
2) Diabetic Complications
Some clinical evidence supports the use of infrared light for diabetic complications such as diabetic foot ulcers.
In a study of 50 diabetic patients, one week of infrared therapy healed diabetic foot ulcers. After one month, the patients’ ulcers shrank in size and had fewer secretions. The infrared lamp helped prevent infection [11].
However, insufficient evidence supports the use of infrared light for controlling sugar levels and other symptoms in people with type 2 diabetes.
In a study of 10 type II diabetic patients, infrared light therapy helped lower blood glucose levels. The authors hypothesized that infrared radiation might reduce insulin resistance and lower cortisol (stress hormone) levels. This has yet to be determined [12].
In another study of 15 middle-aged type II diabetes patients, three months of far-infrared sauna therapy improved the patients’ quality of life. The patients also reported an improvement in fatigue, stress, and physical and emotional health. This study was small and had other design-related limitations. More research is needed [13].
3) Heart Health
There is some evidence support far infrared sauna efficacy for high blood pressure and congestive heart failure. On the other hand, there is solid evidence to refute claims about the ability of far infrared saunas to reduce cholesterol [14].
In a clinical study, daily infrared sauna therapy lowered blood pressure in patients with increased risk for heart disease [14].
Repeated infrared sauna therapy helped improve heart function in patients with increased heart disease risk. After two weeks of daily sauna therapy, the patients also had improved blood flow [15].
Researchers are investigating whether far-infrared radiation increases miRNA-31 and miRNA-720, a mechanism that may improve heart cell function in heart disease patients [16].
4) Inflammation
Some low-quality evidence supports the use of infrared light for reducing inflammation and pain from rheumatoid arthritis.
In a small study (DB-RCT) of 37 arthritis patients, infrared pulsed laser devices (low level laser therapy at 810 nm) reduced inflammatory cytokines (TNF, IL-1, and IL-2). The patients had improvement in function and pain after a few months [17].
Limited research suggests that infrared radiation therapy may reduce arthritic joint inflammation in the short term when used as an add-on to clinical treatment [18].
Infrared light significantly reduced immobility in rats with artificially induced arthritis by lowering inflammatory cytokines and decreasing vessel permeability [18].
5) Exercise Recovery
Some researchers consider that infrared radiation may help reduce the inflammation and soreness associated with post-exercise recovery and shorten recovery periods. In theory, this would allow for more intense and frequent training and improved results. Nonetheless, proper clinical data are lacking [19, 20].
In a small human study, infrared emitting fabrics improved the performance of soccer players during normal training. The players wore the fabrics for ten hours at night and saw a moderate decrease in muscle soreness 24 and 72 hours after exercise [19].
In one animal study, 904 nm laser irradiation stimulated rat muscle tissue. It reduced the production of two inflammatory enzymes, COX-1 and COX-2, which allowed the muscle tissue to perform a total work in subsequent testing [21].
More human trials will be required to repeat these results and to determine the role of infrared light in improving physical performance and recovery from exercise.
6) Circulation
Researchers are investigating if extended periods of infrared radiation can increase circulation and improve blood vessel function. The existing results are inconclusive [22].
In a study (RCT) of 61 kidney dialysis patients, far infrared radiation increased blood flow and oxygen levels in the body. This helped reduce fatigue [23].
Through both thermal and nonthermal mechanisms, infrared radiation improved circulation in rats. Far infrared therapy increased blood flow for up to 60 minutes, while skin temperature was held constant [22].
Scientists suspect the results were not simply due to an increase in temperature, but rather the interaction of infrared light with the L-arginine/Nitric oxide pathway [22].
Other researchers are exploring the effects of infrared light on cells. IR seems to increase HO-1 gene production by raising temperature, which would theoretically reduce abnormal blood flow [24].
HO-1 may prevent thickening of blood vessels, platelet aggregation, and vasospasms, all of which can contribute to obstruction of blood flow. Additionally, it stimulates endothelial cell regrowth at injury sites, further aiding in vessel health and contributing to healthy circulation [24].
7) Mood
There is insufficient evidence to support the use of infrared light for mood disorders.
In a study of 70 participants, far infrared light treatment at acupuncture points increased their serotonin levels. Increasing serotonin levels may help increase mood [25].
In rats, long-term infrared light treatment reduced anxiety and depression-like behaviors. However, short-term infrared radiation had no effect on their behavior [26].
8) Hay Fever
Solid evidence is lacking to support the use of infrared light for hay fever. In a study of 31 allergic rhinitis (hay fever) patients, far infrared therapy improved their symptoms. The patients had less stuffiness, eye and nose itching, and sneezing. However, these findings have not been replicated. Much more research is needed [27].
Animal & Cell Research (Lacking Evidence)
No clinical evidence supports the use of infrared light therapy for any of the conditions listed in this section. Below is a summary of the existing animal and cell-based research, which should guide further investigational efforts. However, the studies listed below should not be interpreted as supportive of any health benefit.
9) Wound Healing
Solid clinical evidence suggests that IR light improves delayed wound healing, such as the healing of burns, amputation injuries, skin grafts, infected wounds, and trapping injuries [28].
Additionally, infrared radiation therapy increased the rate at which skin wounds healed in rats [29].
Far-infrared rays increased the levels of key factors in the healing process (such as TGF-β1) as well as the activity of fibroblasts (connective tissues) and other reparative cell types [29].
Increasing TGF-β1 reduces the production of key inflammatory factors. Reducing the duration and intensity of the secretion of these factors shortens the inflammatory response period, allowing wound healing to move into the proliferative period quicker [29].
In addition to increasing TGF-β1, infrared light therapy increased connective tissue formation and collagen production in both human and mouse cells. One study showed epithelial cell growth increasing by up to 171% when exposed to near-infrared light therapy [30].
Cancer Research
Infrared light has not been shown to treat or prevent cancer.
Some scientists have speculated about whether photodynamic therapy has any effect on cancer cells. In dishes, nanoparticles that are exposed to near-infrared radiation can become toxic to nearby cancer cells. In mice, infrared radiation had some anti-tumor properties [31, 32].
Photoimmunotherapy is another experimental approach. Scientists believe it binds the materials that manipulate light and heat (photothermal) to an antibody targeted specifically to the cancer cells. Upon binding to receptors on the surface of the cancer cells, infrared light is again used to cause the particles to heat up, which may have anti-cancer effects [33].
However, many modalities have anti-cancer effects in cells, including techniques that kill all cells like extreme heat. This doesn’t mean that they have any medical value. In fact, most techniques that are researched in cancer cells and animals fail to pass further clinical trials due to a lack of safety or efficacy.
Side Effects of Infrared Radiation
Infrared radiation can only penetrate approximately 4 cm into the human body, so the primary risks of infrared radiation exposure are to the skin and the eyes [5].
Additionally, large-scale safety trials should determine the long-term side effects of infrared radiation, different wavelengths, and light “dosages.”
Therefore, this is not intended to be a complete list of potential adverse effects of infrared radiation.
Skin Damage
Approximately 65% of the infrared radiation that reaches the human body penetrates to the dermis before absorption. At this point, one potential concern is an increase in photoaging (aging due to light) [34].
UV rays are the main agents of photoaging, but one study found that increased exposure to infrared radiation increased MMP-1 production. MMP-1 is a potential contributor to photoaging, which decreases collagen and elastin production in the skin [34].
The increase in skin temperature can also have negative effects. An increase in temperature via induced heat shock can lead to the creation of reactive oxygen species, which may cause damage over time [35].
Infrared radiation may also harm tattooed skin. In one man, far infrared light caused skin inflammation (pseudolymphoma) [36].
Eye Damage
The lens of the eye is extremely sensitive to infrared radiation. Long-term exposure of high power sources may contribute to cataract formation [37].
Infrared radiation can damage crucial proteins that facilitate the normal function and passage of ions and enzymes through the lens. This could reduce the clarity of the lens [37].
Caveats
There are not many available human clinical trials that use infrared radiation. Additionally, most of the available human studies are not high quality (not double-blind or have a large sample size).
Consult a doctor before going to an infrared sauna.
Pregnant women, children, the elderly, and people with a weak immune system should avoid infrared light due to a lack of safety data and the dangers of excess heating.
Takeaway
Infrared therapy is a technique by which infrared wavelengths of light are applied to inflamed or diseased tissues. Its proponents believe that by heating the tissues, infrared light improves circulation and decreases inflammation, thereby improving wound healing and other processes.
So far, the best evidence for infrared light is for psoriasis, diabetic ulcers, and general inflammation. Many popular applications of infrared therapy do not have sufficient evidence to recommend it.
