What Does LED and Infrared Therapy Do?


Overview of Research and Literature Light therapy has been shown in over 40 years of independent research worldwide to deliver powerful therapeutic benefits to living tissues and organisms. Both visible red and infrared light have been shown to effect at least 24 different positive changes at a cellular level. Light radiation must be absorbed to produce a biological response. All biological systems have a unique absorption spectrum which determines which wavelengths of radiation will be absorbed to produce a given therapeutic effect. The visible red and infrared portions of the spectrum have been shown to be highly absorbent and produce unique therapeutic effects in living tissues. 

What Does Infrared Therapy Actually Do? Light therapy has been shown to Increase vascularity (circulation) by increasing the formation of new capillaries, which are additional blood vessels that replace damaged ones. New capillaries speed up the healing process by supplying additional oxygen and nutrients needed for healing. Stimulate the production of collagen. Collagen is the most common protein found in the body. Collagen is the essential protein used to repair and replace damaged tissue. It is the substance that holds cells together with a high degree of elasticity. Increasing collagen production will decrease scar tissue at the injured site. Stimulate the release of adenosine triphosphate (ATP). ATP is the major carrier of energy to all cells. Increases in ATP allow cells to readily accept nutrients and expel waste products faster by increasing the energy level in the cell. All food turns into ATP before it is utilized by the cells. ATP provides the chemical energy that drives the chemical reaction of the cell. Increase lymphatic system activity. Edema, which is the swelling or natural splinting process of the body, has two basic components. The first is a liquid part which can be evacuated by the blood system and the second is comprised of the proteins which have to be evacuated by the lymphatic system. Research has shown that the lymph vessel diameter and the flow of the lymph system can be doubled with the use of light therapy. The venous diameter and the arterial diameters can also be increased. This means that both parts of edema (liquid and protein) can be evacuated at a much faster rate to relieve swelling. Increase RNA and DNA synthesis. This helps damaged cells to be replaced more promptly. Reduce the excitability of nerve tissue. The photons of light energy enter the body as negative ions. This requires the body to send positive ions, calcium among others, to flow to the area being treated. These ions assist in regulating the nerves, thereby relieving pain. Stimulate fibroblastic activity which aids in the repair process. Fibroblasts are present in connective tissue and are capable of forming collagen fibers. Increase phagocytosis, which is the process of scavenging for and ingesting dead or degenerated cells by the phagocyte cells. This is an important part of the infection control process. The healing process depends upon the Destruction of infection and cellular clean up. 

Induce a thermal like effect in the tissue. The light raises the temperature of the cells although there is no heat produced from the diodes themselves. Stimulate tissue granulation and connective tissue projections, which are part of the healing process of wounds, ulcers or inflamed tissue. Stimulate acetylcholine release. Acetylcholine causes cardiac inhibition, vasodilation, gastrointestinal peristalsis and other parasympathetic effects. The Following Definitions Are Commonly Used with Light Therapeutic devices 1) Visible Light: light that is within the visible spectrum, 400nm(violet) to 700nm(red) 2) Infrared Light: light in the invisible spectrum below red, from 700nm to 2,000nm 3) Frequency: number of cycles per second measured in Hz. 4) Coherency: wavelengths of light traveling in phase with one another 5) Monochromatically: light that is of one color, or one wavelength 6) Collimation: light focused in a beam, maintaining a constant diameter regardless its distance from the object or surface directed toward 7) Nanometer (nm): a unit of measure of wavelength of light (one billionth of a meter) 8) Nanosecond: one billionth of a second 9) Joule (J): unit used to measure the energy delivered 10) Watts (w) and milliwatts (mw, 1/ 1000th of a watt): units used to measure the power capability 11) Peak power: output: the maximum output of power, measured in milliwatts and watts 12) Average power: amount of power actually delivered in a given period of time 13) Duty cycle: the amount of time the light is actually on during a given period of time Depth of Penetration Depth of penetration is defined as the depth at which 60% of the light is absorbed by the tissue, while 40% of the light will continue to be absorbed in a manner that is less fully understood. Treating Trigger points with Light can have a dramatic effect on remote and internal areas of the body through the stimulation of nerves, acupuncture and trigger points that perform a function not unlike transmission cables. The diverse tissue and cell types in the body all have their own unique light absorption characteristics; that is, they will only absorb light at specific wavelengths and not at others. For example, skin layers, because of their high blood and water content, absorb red light very readily, while calcium and phosphorus absorb light of a different wavelength. Although both red and infrared wavelengths penetrate to different depths and affect tissues differently, their therapeutic effects are similar. Visible red light, at a wavelength of 660 nanometers (nm – 1 nanometer is equal to one billionth of a meter), penetrates tissue to a depth of about 8-10 mm. It is very beneficial in treating problems close to the surface such as wounds, cuts, scars, trigger and acupuncture points and is particularly effective in treating infections. Infrared light (904nm) penetrates to a depth of about 30-40 mm which makes it more effective in the treatment of joints, deep muscle, etc. What is the Difference between LED’s and LASERS? Dr. Kendric C. Smith at the Department of Radiation Oncology, Stanford University School 

of Medicine, concludes in an article entitled The Photobiological Effect of Low Level Laser Radiation Therapy (Laser Therapy, Vol. 3, No. 1, Jan – Mar 1991) that “1) Lasers are just convenient machines that produce radiation. 2) It is the radiation that produces the photobiological and/or photophysical effects and therapeutic gains, not the machines. 3) Radiation must be absorbed to produce a chemical or physical change, which results in a biological response.” LED’s and LASERS both produce electromagnetic radiation at specific wavelengths. Several studies establish that it is the light itself at specific wavelengths, which is therapeutic in nature and not the machine producing it. For example, In the majority of lasers on the market, the energy output varies with the frequency setting: the lower the frequency, the lower the output. Even in the case of lasers that have a peak output of 10 watts, the average output at the highest frequencies is of the order of about 10 milliwatts because of the very short duty cycle. At the lower frequencies, however, the average output plummets into the range of microwatts (1 microwatt = 1000th of 1 milliwatt). LEDs are neither coherent nor collimated and they generate a broader band of wavelengths than do the single-wavelength laser. Non-collimation and the wide-angle diffusion of the LED confer upon it a greater ease of application, since light emissions are thereby able to penetrate a broader surface area. Moreover, the multiplicity of wavelengths in the LED, contrary to the single-wavelength laser, may enable it to affect a broader range of tissue types and produce a wider range of photochemical reactions in the tissue. The LED dispersesment over a greater surface area results in a faster treatment time for a given area than laser. LEDs are safer, more cost effective, provide a gentle but effective delivery of light and a greater energy output per unit of surface area in a given time duration. They are offered in combinations of visible red light at 660nm and infrared light at from 830nm to 930nm, with 880nm as their average. Light Emitting Diodes (LEDs) are a form of light therapy that is a relatively recent development of the laser industry. LEDs are similar to lasers inasmuch as they have the same healing effects but differ in the way the light energy is delivered. A significant difference between lasers and LEDs is the power output. The peak power output of LEDs is measured in milliwatts, while that of lasers is measured in watts. However, this difference when considered alone is misleading, since the most critical factor that determines the amount of energy delivered is the duty cycle of the device. LED devices usually have a 50% duty cycle. That is, the LED pulse is “on” for 0.5 seconds and “off” for 0.5 seconds versus the 2 ten-millionths of a second burst from laser at 1 cycle per second (1 hz.). Moreover, LED is “on” 50% of the time and “off” 50% of the time regardless of what frequency setting (pulses per second) is used. LEDs do not deliver enough concentrated energy to damage the tissue, but they do deliver enough energy to stimulate a response from the body to heal itself. With a low peak power output but high duty cycle, the LEDs provide a much gentler delivery of the same healing wavelengths of light as does the laser but at a substantially greater energy output. For this reason, LEDs do not have the same risk of accidental eye damage that lasers do. 

Hot and Cold Lasers Lasers are of two principal types, “hot” and “cold”, and they are distinguished by the amount of peak power they deliver. “Hot” lasers deliver power up to thousands of watts. They are used in surgery because they can make an incision that is very clean with little or no bleeding and because the laser cauterizes the incision as it cuts. They are also used in surgery that requires the removal of unhealthy tissue without damaging the healthy tissue that surrounds it. . “Cold” lasers produce a lower average power of 100 milliwatts or less. This is the type of laser that is used for therapeutic purposes and it is typically, although not always, pulsed. The light is actually on for only a fraction of a second because it is pulsed rapidly during the time frame. Pulsation results in an average power output that is very low compared to the maximum or peak output. Hence, most therapeutic lasers produce a high peak but low average power output. Therapeutic laser light is generally either visible (red, in most cases) or invisible (infrared). However, most therapeutic lasers operate at 904 nm, which is an infrared light. Side Effects At this time, research has shown no side effects from this form of therapy. Occasionally, one may experience an increase in pain or discomfort for a short period of time after treating chronic conditions. This occurs as the body reestablishes new equilibrium points following treatment. It is a phenomenon that may occur as part of the normal process of recovery. REFERENCES The Photobiological Basis of Low Level Laser Radiation Therapy, Kendric C. Smith; Stanford University School of Medicine; Laser Therapy, Vol. 3, No. 1, Jan – Mar 1991 Low-Energy Laser Therapy: Controversies & Research Findings, Jeffrey R. Basford MD; Mayo Clinic; Lasers in Surgery and Medicine 9, pp. 1-5 (1989) New Biological Phenomena Associated with Laser Radiation , M.I. Belkin & U. Schwartz; Tel-Aviv University; Health Physics, Vol. 56, No. 5, May 1989; pp. 687-690 Macrophage Responsiveness to Light Therapy, S Young Ph.D., P Bolton BSc, U Dyson PH, W Harvey Ph.D., & C Diamantopoulos BSc; London: Lasers in Surgery and Medicine, 9; pp. 497-505 (1989) Photobiology of Low-Power Laser Effects, Tina Karu Ph.D.; Laser Technology Centre of Russia; Health Physics, Vol. 56, No. 5. May 89, pp. 691-704 A Review of Low Level Laser Therapy, S Kitchen MSCMCSP & C Partridge Ph.D.; Centre for Physiotherapy Research, King’s College London Physiotherapy, Vol. 77, No. 3, March 1991 Systemic Effects of Low-Power Laser Irradiation on the Peripheral & Central Nervous System, Cutaneous Wounds & Burns, S Rochkind MD, M Rousso MD, M Nissan Ph.D., M Villarreal MD, L Barr-Nea Ph.D.. & 

DG Rees Ph.D., Lasers in Surgery and Medicine, 9; pp. 174-182 (1989) Use of Laser Light to Treat Certain Lesions in Standardbreds, LS McKibbin DVM, & D Paraschak BSc., MA; Mod Veterinary Practice, March 1984, Sec. 3, p. 13 Low Level Laser Therapy: Current Clinical Practice In Northern Ireland, GD Baxter BSc, AJ Bet, MA, JM Atien PhD, J Ravey Ph.D.; Blamed Research Centre University Ulster Physiotherapy, Vol. 77, No. 3, March 1991 The Effects of Low Energy Laser on Soft Tissue in Veterinary Medicine, LS McKibbin & R Downie; The Acupuncture Institute, Ontario Canada; J. Wiley & Sons A Study of the Effects or Lasering of Chronic Bowed Tendons, Wheatley, LS McKibbin DVM, and DM Paraschak BSc MA; Lasers in Surg & Medicine, Vol. pp. 55-59 (1983) Scc 3 Lasers and Wound Healing, Albert J. Nemeth, MD; Laser and Dermatology Center, Clearwater FL, Dermatologic Clinics, Vol.. 11 #4, 1993 Low Level Laser Therapy: A Practical Introduction, T. Ohshiro & RG Caiderhead, Wiley and Sons Low Reactive-Level Laser Therapy: A Practical Application, T. Ohshiro; Book: Wiley and Sons Laser Biostimulation of Healing Wounds: Specific Effects and Mechanisms of Action, Chukuka S Enwemeka, Ph.D.; Assistant Professor of Physical Therapy – U. of Texas, Health Science Center, San Antonio, TX; The Journal of Orthopaedic & Sports Physical Therapy, Vol. 9. No.10, 1988 Effect of Helium-Neon and Infrared Laser Irradiation on Wound Healing in Rabbits, B Braverman, Ph.D.; R McCarthy. Pharmd, A Lyankovich, MD; D Forde, BS, M Overfield, BS and M Bapna, Ph.D.; Rush- Presbyterian-St. Luke’s Medical Center; University of Illinois, Lasers in Surgery and Medicine 9:50-58 (1989) Bone Fracture Consolidates Faster With Low-Power Laser, MA Trelles, MD and E Mayayo, MD, Barcelona, Spain; Lasers in Surgery & Med. 7:36-45 (1987) Wound Management with Whirlpool and Infrared Cold Laser Treatment, P Gogia; B Hurt and T Zim; AMI-Park Plaza Hospital, Houston TX, Physical Therapy, Vol. 68, No. 8, August 1988 Effects of Low-Level Energy Lasers on the Healing of Full-Thickness Skin Defects, J Surinchak. MA; M Alago, BS,, R Bellamy, MD; B Stuck, MS and M Belkin, MD; Lettennan Army Institute of Research. Presido of San Fransico, CA; Lasers in Surgery & Medicine, 2:267-274 (1983) 

Biostimulation of Wound Healing by Lasers: Experimental Approaches in Animal Models and in Fibroblast Cultures, RP Abergel, MD; R Lyons. MD; J Castel, MS, R Dwyer. MD and I Uitlo. MD, Ph.D.; Harbor UCLA Medical Center. CA: J Dennatol. Surgery Oncol., 13:2 Feb. 1987 Effects of Low Energy Laser on Wound Healing In a Porcine Model, J Hunter, MD; L Leonard, MD; R Wilsom MD; G Snider, MD and J DLxon, MD; Department of Surgery, University of Utah Medical Center, Salt Lake City UT, Lasers in Surgery & Med. 3:285-290, 84 Effect of Laser Rays on Wound Healing, E Mester, MD; T Spiry, MD; B Szende. MD and J Tola; Semmelweis Medical Univ. Budapest, The American Journal of Surgery. Vol. 122, Oct 1971 Low Level Laser Therapy in the United Kingdom, Kevin C Moore, MD; The Royal Oldham Hospital, Oldhant, UK Effects of Skin-Contact Monochromatic Infrared Irradiation on Tendonitis, Capsulitis and Myofascial Pain, T.L. Thomasson DDS, 19th Annual Scientific Meeting, American Academy of Neurological & Orthopaedic Surgeons, Aug. 27-30, 1995 Facial Pain/TMJ Centre, Denver, CO.

2239 Patient Study on Peripheral Neuropathy and Light Therapy

 Improved foot sensitivity and pain reduction in patients with peripheral neuropathy after treatment with monochromatic infrared photo energy–MIRE. 

Harkless LB, DeLellis S, Carnegie DH, Burke TJ. 


Department of Orthopaedics and Podiatry, University of Texas Health Science Center San Antonio, TX 78229, USA. 


The medical records of 2239 patients (mean age=73 years) with established peripheral neuropathy (PN) were examined to determine whether treatment with MIRE was, in fact, associated with increased foot sensitivity to the Semmes Weinstein monofilament (SWM) 5.07 and a reduction in neuropathic pain. The PN in 1395 of these patients (62%) was due to diabetes. Prior to treatment with MIRE, of the 10 tested sites (5 on each foot), 7.1+/-2.9 were insensitive to the SWM 5.07, and 2078 patients (93%) exhibited loss of protective sensation defined by Medicare as a loss of sensation at two or more sites on either foot. After treatment, the number of insensate sites on both feet decreased to 2.4+/-2.6, an improvement of 66%. Of the 2078 (93%) patients initially presenting with loss of protective sensation, 1106 (53%) no longer had loss of protective sensation after treatment (P<.0001); 1563 patients (70%) also exhibited neuropathic pain in addition to sensory impairment. Prior to treatment with MIRE, pain measured on the 11-point visual analogue scale (VAS) was 7.2+/-2.2 points, despite the use of a variety of pain-relieving therapeutic agents. After treatment with MIRE, pain was reduced by 4.8+/-2.4 points, a 67% reduction. Therefore, MIRE appears to be associated with significant clinical improvement in foot sensation and, simultaneously, a reduction in neuropathic pain in a large cohort of primarily Medicare aged, community-dwelling patients, initially diagnosed with PN. The quality of life associated with these two outcomes cannot be underappreciated. 



[PubMed – indexed for MEDLINE] 

5000 Patients Studied with Light Therapy

A Proven Theory

Near Infrared (NIR) light has been the subject of at least 15 studies involving

nearly 5,000 patients. The results have been published in multiple journals such as

Diabetes Care, Age and Aging, Practical Pain Management, Physical and

Occupational Therapy in Geriatrics and the Journal of Diabetes and its

Complications. Most of these studies involved patients with diabetic peripheral

neuropathy. Significant pain reduction and improved sensation were routinely


Researchers from the Joslin Center for Diabetes in Clearwater, Florida examined

the effects of NIR on patients with diabetic peripheral neuropathy (DPN). This

common and devastating condition, which plagues many people with diabetes,

impairs sensation and often leads to falls and amputations. The researchers gave

study participants 12 treatments of either infrared therapy or a sham treatment and

concluded that NIR treatments “improve sensation in the feet of subjects with

DPN, improve balance, and reduce pain.”- Leonard DR, et al. Diabetes Care.

2004 Jan, 27(1): 168-72

Infrared Light Therapy, or photo-biomodulation, is a unique therapy that harnesses

the healing powers of infrared light. It emits specials wavelengths of light energy

that dramatically increase circulation to injury sites and areas of chronic pain. The

result is a rapid relief of discomfort, improvement in sensation, and regeneration

of damaged tissues.

How Does Infrared Light Therapy Work?

Treatment with the NIR light system is simple and painless. Flexible pads,

containing multiple infrared and visible red diodes, are placed directly on the skin

over the area of pain or injury. Light energy from the diodes penetrates beneath

the skin and is absorbed by proteins within cells that lay beneath the skin. Those

cells release nitric oxide, the body’s natural vasodilator. After just 20 minutes of

treatment, blood flow is increased to nerves and other tissues, and this boost in

local circulation persists for several hours after the pads are removed.

The Power Of Nitric Oxide

The key to this dramatic improvement in blood flow is nitric oxide, a short-lived

gas that is crucial to the health of the arteries. This powerful signaling molecule

relaxes the arteries, helps regulate blood pressure, fights free radicals and

discourages platelets from clumping together in the blood vessels. By increasing

the production of nitric oxide and improving circulation, NIR light therapy

promotes healing and relieves pain.

Chronic Pain Relief

NIR light therapy has been used by the US military to speed recovery from softtissue

injuries in elite soldiers in the Navy SEALs, Army Rangers, and Special

Forces. Hospitals, nursing homes and long-term care facilities use it to accelerate

the healing of pressure ulcers (bed sores) and decrease the number of falls in

elderly patients. This therapy is also used to ease the pain of neuropathy, restore

sensation to patients with nerve impairment, speed up the healing of diabetic

ulcers and other wounds and relieve many kinds of chronic pain.


Medical Applications of Space Light-Emitting Diodes

Technology—Space and Beyond


Space light-emitting diode (LED) technology has provided medicine with a new

tool capable of delivering light deep into tissues of the body, at wavelengths

which are biologically optimal for cancer treatment and wound healing. This

LED technology has already flown on space shuttle missions, and shows promise

for wound healing applications of benefit to Space Station astronauts and in

special operations.

The full-length article is available in Space Tech. & App. Int’l. Forum -1999, vol 458:3-15. 1999-00, Medical

College Of Wisconsin

Wound Healing

Wounds heal less effectively in space than here on Earth. Improved wound healing may have multiple applications

which benefit civilian medical care, military situations and long-term space flight. Laser light and hyperbaric

oxygen have been widely acclaimed to speed wound healing in ischemic, hypoxic wounds. Lasers provide low

energy stimulation of tissues which results in increased cellular activity during wound healing. Some of these

activities include increased fibroblast proliferation, growth factor synthesis, collagen production and angiogenesis.

Hyperbaric oxygen therapy has also been shown to affect these processes.

Lasers, however, have some inherent characteristics which make their use in a clinical setting problematic,

including limitations in wavelength capabilities and beam width. The combined wavelengths of light optimal for

wound healing cannot be efficiently produced, and the size of wounds which may be treated by lasers is limited.

Light-emitting diodes (LED’s) offer an effective alternative to lasers. These diodes can be made to produce

multiple wavelengths, and can be arranged in large, flat arrays allowing

treatment of large wounds.

Our experiments suggest potential for using LED light therapy at 680, 730

and 880 nm simultaneously, plus hyperbaric oxygen therapy, both alone

and in combination, to accelerate the healing process in Space Station

missions, where prolonged exposure to microgravity may otherwise retard


Studies on cells exposed to microgravity and hypergravity indicate that

human cells need gravity to stimulate cell growth. As the gravitational force

increases or decreases, the cell function responds in a linear fashion. This

poses significant health risks for astronauts in long term space flight.

The application of light therapy with the use of NASA LED’s will significantly improve the medical care that is

available to astronauts on long term space missions. NASA LED’s stimulate the basic energy processes in the

mitochondria (energy compartments) of each cell, particularly when near-infrared light is used to activate the color

sensitive chemicals (chromophores, cytochrome systems) inside. Optimal LED wavelengths include 680, 730 and

880 nm. Our laboratory has improved the healing of wounds in laboratory animals by using NASA LED light and

hyperbaric oxygen. Furthermore, DNA synthesis in fibroblasts and muscle cells has been quintupled using NASA

LED light alone, combining 680, 730 and 880 nm each at 4 Joules per centimeter squared

Muscles and Bones

Muscle and bone atrophy are well documented in astronauts, and various minor injuries occurring in space have

been reported not to heal until landing on Earth. Long term space flight, with its many inherent risks, also raises

the possibility of astronauts being injured performing their required tasks. The fact that the normal healing process

is negatively affected by microgravity requires novel approaches to improve wound healing and tissue growth in

space. NASA LED arrays have already flown on Space Shuttle missions for studies of plant growth. The U.S.

Food and Drug Administration (FDA) has approved human trials. The use of light therapy with LED’s is an

approach to help increase the rate of wound healing in the microgravity environment, reducing the risk of treatable

injuries becoming mission catastrophes.

Special Operations

Special Operations are characterized by lightly equipped, highly mobile troops

entering situations requiring optimal physical conditioning at all times. Wounds are

an obvious physical risk during combat operations. Any simple and lightweight

equipment which promotes wound healing and musculoskeletal rehabilitation and

conditioning has potential merit.

NASA LED’s have proven to stimulate wound healing at near-infrared wavelengths

of 680, 730 and 880 nm in laboratory animals, and have been approved by the U.S.

Food and Drug Administration (FDA) for human trials. Furthermore, near-infrared

LED light has quintupled the growth of fibroblasts and muscle cells in tissue

culture. The NASA LED arrays are light enough and mobile enough to have

already flown on the Space Shuttle numerous times.

LED arrays may be used for improved wound healing and treatment of problem wounds as well as speeding the

return of deconditioned personnel to full duty performance. Examples include:

1. promotion of the rate of muscle regeneration after confinement or surgery.

2. personnel spending long periods of time aboard submarines may use LED arrays to combat muscle atrophy

during relative inactivity.

3. LED arrays may be introduced early to speed wound healing in the field.

4. hyperspectral sensors being developed at NASA Stennis Space Center by ProVision Technologies may

provide early evidence of wound healing problems and monitor the effectiveness of LED treatment.

Our laboratory gratefully acknowledges the contributions of

LT Christopher J. Cassidy, USN

who serves as the U.S. Navy SEAL Advisor to this project.

Naval Special Warfare Group TWO Medical Consultants:

LCDR Alan F. Philippi

LCDR Pete Johnson

LT Geoffrey M. Fitzgerald

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