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L.E.D. light: Speed the Healing

LED Therapy FAQ

Why can't I see light from some of the LED's?
These LEDs (880 nm) are on and working properly. You cannot see them because they are in the infrared spectrum, which is not visible to the human eye. Some digital cameras and camcorders will display the infrared lights.

What is the difference between Laser or LED?
LED's produce (non-coherent, monochromatic light; spontaneous emission) - Laser's produce (coherent, monochromatic light, stimulated emission)

Tiina Karu (1998: The Science of Low-Power Laser Therapy) states that "...the coherence of light is of no importance in low-power laser clinical effects" and "the primary difference between lasers and LED's is that the laser's coherent beam produces "speckles" of relatively high power density which can cause local heating of inhomogeneous tissues".

Currently researchers & scientist agree that LED's are effective in generating a response within living tissue and hence has a therapeutic effect if used properly.

Most published research on photorejuvenation has been conducted using Lasers and not LED's. Only within the the last decade have LED's been produced with a strong enough output power to be beneficial for photo rejuvenation

NASA has produced the best research documentation to date supporting the effectiveness of LED's to stimulate plants and human tissue. Until more research is completed on the success of LED's for photorejuvenation the effectiveness is still not supported by extensive research.

To summarize, both LED's and Laser's work, but more research is needed to determine their best suited role LED's will play in photo-rejuvination.

Speed the Healing of Cuts
By pulsing red and infrared light emitting diodes (LEDs) on cuts, the speed of healing is greatly increased. Red and infrared wavelengths from 660 nm (nanometers) to 880 nm penetrate the skin more effectively than other wavelengths. Photons stimulate the mitochondria and this triggers a healing response. This is because the machinery of our cells is photosensitive. By pulsing the LEDs at 292 Hz, the healing is speeded even more by raising the vibrational rate of the damaged skin up to the frequency of healthy skin tissue by entrainment. 

The discovery that LEDs can help cuts heal faster would not have been possible if laser therapists hadn’t been paying attention. When normal lasers are used, not only does the target area get burned, but the surrounding skin gets burned as well. Over time, it was observed that the surrounding skin that was burned heals faster than skin normally does when burned by other means. It was thought that turning the power on the lasers way down and directing the beam over damaged skin might speed the healing of cuts and burns. This is one form of Low Level Laser Therapy or LLLT. Supporters of LLLT claim that it works better than LEDs, but the fact is when the laser light hits the skin, it becomes non-coherent. LEDs are a very inexpensive non-coherent light source at the same wavelengths that the lasers use and much less power is required.

Most people are familiar with LEDs and don’t even know it. Most power indicator lights on electronic devices are LEDs. So are the ones on the ends of remote controls. The power indicator lights emit light that is in the visible spectrum and the LEDs at the end of remote controls emit light in the invisible infrared range. LEDs are known as p-n semiconductors. The p is the positive electrode and the n is the negative electrode. They connect to the semiconductor material on each side of a junction. When enough voltage is supplied to the positive end it recombines with the negative side by bridging the gap. The excess energy is converted into light. The color of light emitted depends on the ratio of each material that is mixed together to make the silicon diode. 

Pulsing these LEDs at different frequencies can increase the effectiveness of the LED treatments. Dr. Paul Nogier, the father of ear acupuncture, discovered that each tissue type in the body resonates at different frequencies depending on the embryologic origin of tissue. Someone would lie down on his or her back and he would check their radial artery pulse. Using a frequency generator, he dialed in different frequencies and aimed them at different parts of the body and also on different acupuncture points. If the frequencies were beneficial, the peak wave amplitude of the pulse would shift in a certain direction. If the frequencies were not beneficial, the shift would be in the opposite direction. He found that tissue derived from ectodermal tissues had a positive response to 292 Hz. Tissue derived from endodermal tissues responded best to 584 Hz and tissue derived from mesodermal tissues responded best to 1168 Hz. These frequencies are all harmonics of each other and happen to be harmonics of the D note. 

Most of these lights are in portable hand held devices or in flexible foam blankets with the LEDs embedded throughout them. These blankets are used to treat large areas. The hand held devices and blankets have mostly been used by holistic veterinarians and especially by equestrian acupuncturists for about 20 years already. Shining a pulsed red LED set to 292 Hz on a cut has been shown to increase the speed of healing. Even without pulsing the LEDs, the speed of healing is incredibly increased. When submariners with lacerations were treated with non-pulsed LEDs, the wounds healed twice as fast as in the untreated controls. Even the Navy Seals and astronauts are benefiting greatly from this technology and they aren’t even using any of the pulsed frequencies. 

Where are we headed with all of this healing light technology? With big interests such as NASA diving deeply into the research and development of this technology, it is sure to get more and more attention. Obviously the costs of these devices will begin to get more affordable as we find cheaper ways of making them. Quantum Devices is a LED therapy device company that NASA is working with and they have a relatively low priced LED device available for $15,000 that is low compared to a $150,000 diode laser system.

Other companies such as Chee Energy located in Coeur d’Alene, Idaho have devices available for around $500 plus or minus a few hundred dollars and they can even fit in a pocket. With more affordable pricing like that, the market is enormously enlarged. If you would like to try and experience the benefits of this Star Trek medicine yourself, go to your local Radio Shack and purchase the brightest red LED, battery, resistor, small project box and switch. The folks there will be able to tell you which parts you need and how to put together this simple project. The whole thing should cost between $5-10. It’s as simple as the circuitry in a flashlight except that the light is not a bulb; it is a LED. The whole thing will fit easily in the palm of your hand depending on what you use for a case.

This kind of cheap homemade unit won’t have the benefits of the Nogier’s frequencies and it won’t look too fancy, but for minimal effort, you will be able to have a workable unit. Just use your own imagination. Use it on minor cuts as soon as they happen for 15 minutes twice a day until it is totally healed and I’m sure you will be amazed at just how fast light emitting diodes speed the healing of cuts.

McGee, Charles MD. Healing Energies of Heat and Light. Coeur d’Alene, ID: Medipress, 2000.

Drollette, Dan. Can Light Hasten Healing in Space? Pittsfield, MA: Biophotonics International, September/October 2000.


Experiments with light energy are making everyone happy: farmers, doctors, patients, and astronauts are all reaping the benefits. What began as a way to grow better crops has ended up being a way to help seriously ill patients recover faster. In this case, what's good for plants is also good for people.

It started with Light Emitting Diodes (LEDs) developed by NASA Marshall Space Flight Center in Alabama and Quantum Devices, Inc., of Wisconsin. The scientists exposed plants aboard the Space Shuttle to the near-infrared light produced by LEDs. They found that the LEDs increased the energy produced in the mitochondria (energy compartments) of each cell. That meant the cells grew faster. Faster-growing plants are good news for farmers; the faster the plants grow, the sooner they can be harvested, processed, and sold.


Right about the same time, Quantum Devices scientists heard physicians discussing the use of laser therapy for their patients. While laser light did accelerate cell growth and healing in patients, there were some significant drawbacks. Lasers can cause tissues surrounding the treatment area to become overheated, they're big and expensive, limited in wavelength (color), and they're not very reliable, said Harry T. Whelan, MD, professor of pediatric neurology and director of hyperbaric medicine at the Medical College of Wisconsin. A light went off, so to speak, and Quantum approached Dr. Whelan about his concerns. Soon they were experimenting to see if using LED instead of laser therapy would improve the quality of treatment for patients.


"LED treatment has been a wonderful advancement," Dr. Whelan says. "LEDs don't heat the tissues the way lasers do; because LED uses longer wavelength (redder) near-infrared light, it penetrates the tissues deeper. And where lasers are more pinpointed in their delivery, LED can treat the entire body. That's useful for treating people with serious burns, crush injuries, and complications of cancer chemotherapy and radiation treatment, where large portions of the body are involved."


LED therapy has been used successfully with diabetic skin ulcers, burns, and severe oral sores caused by cancer treatment. The redder the light, the longer the wavelength, and the longer the wavelength, the more deeply it can penetrate body tissues, Dr. Whalen says. The near-infrared light rays produced by LED are longer than (and therefore superior to) lasers, and Dr. Whelan asserts that this improved therapy could extend to treating brain tumors and injuries. Animal experiments being conducted now direct LED through the head without the use of any surgery. When LED light is used to activate light-sensitive chemotherapy drugs to destroy cancer it is dubbed Photo Dynamic Therapy (PDT). LED light is otherwise used without drugs to stimulate normal cell chemicals, for healing and tissue regeneration.man demonstrates light therapy technique


"LED reacts with cytochromes in the body," says Dr. Whelan. "Cytochromes are the parts of cells that respond to light and color. When cytochromes are activated, their energy levels go up, and that stimulates tissue growth and regeneration. The potential to regenerate tissue, muscle, brain, and bone opens the door to helping people with diseases that previously had no hope of treatment."


The good news about using LED therapy to speed healing made its way back to the space program. Muscle and bone atrophy are well documented in astronauts because microgravity slows the healing process, and alters the function and structure of every cell's mitochondria, Dr. Whelan says. The result is that wounds are slow to heal, and muscles and bones become weaker from time spent in space. The idea of using LED therapy with astronauts sounded appealing

"Using an LED array to cover an astronaut may help prevent the effects of microgravity," says Dr. Whelan. "LED therapy could also be used to help treat conditions that could arise in space that don't respond to treatment because of those microgravity situations. A simple cut might heal faster with LED, but the benefits would be even more notable if an astronaut suffered a severe injury."

Here on Earth, Dr. Whelan says that LED therapy can easily affect our entire population. "Not everyone may need to use LED treatments for themselves, but just about everyone has known someone with cancer or a severe injury," he says. "Knowing that there is hope for diseases that used to have no treatment is good news for everyone."



Courtesy of NASA's Space Operations Mission Directorate
Published by NASAexplores: April 18, 2001


Amid the elixirs and the skincare potions on the market, LED light therapy is beginning to catch on with critics and professionals alike. You'll be very happy to welcome the well-priced Marvel-Mini to your "get me gorgeous" gadget collection. The Marvel-Mini emits a safe light wavelength for 15 minutes a day to help you care for your acne or hyper-pigmentation. Take it up a notch to 24 minutes of treatment and you'll be teaching those wrinkles and fine lines a thing or two.

LED light therapy emits a frequency that significantly increases new tissue growth and stimulates the skin's fibroblasts to produce collagen and elastin proteins -- that means your skin gets firmer and more elastic (yes!). This really helps if you've suffered from scarring or acne-related problems.

There are three color-coded models:

Red: Targets fine lines and wrinkles
Green: Targets hyperpigmentation
Blue: Targets acne

Price: $225 at Bliss (currently on backorder at Amazon).


Once your hair is damaged, it's difficult to repair. Why not get to the root of hair problems by treating your scalp and hair follicles?

Plasma Ion technology uses the sterilization power of ozone combined with 3D micro-massage to deep clean your scalp. LED photorejuvenation promotes healthy skin cells as Ion therapy unclogs pores and helps smooth troubled skin.

LightStim cross section of LED Light Therapy

Laboratory studies have shown that skin cells grow 150-200 percent faster when exposed to certain LED light wavelengths.  Independent research for over 40 years has shown LED Red and Infrared light delivers powerful therapeutic benefits to living tissue.  Both visible Red and Infrared light has been shown to affect at least 24 different positive changes at a deep level.  Visible Red light, at wavelengths from 630-660 nanometers penetrates tissue to a depth of 8-10 mm.  LED light is very beneficial in treating problems close to the skins surface such as wounds, cuts, and scars. 
Skin layers, because of their high blood and water content, absorb red light very readily and deliver enough energy to stimulate a response from the body to heal itself.

LED Photons must be absorbed to produce a biological response.  All biological systems have a unique absorption spectrum, this uniqueness determines which wavelengths of light 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 restorative effects in living tissues.  It is thought that light photons are absorbed by the skin and underlying tissue and triggers biological changes within the body in a process know asphotobiomodulation.  Although the exact mechanism of action is still undergoing study, what is know is that monochromatic light increases oxygen and blood flow, facilitating wound healing.

More Scientific Studies

Curing with light was known and used in medicine in ancient times. Red or ultraviolet light was successfully used in the 19th century for the treatment of pockmarks and lupus vulgaris by Danish physician, N. R. Finsen, the father of contemporary phototherapy. 

Biological phenomena induced by ultraviolet light have been intensively investigated in photobiology and photo medicine for several decades. Ultraviolet light as a phototherapy for some dermatological diseases (mainly psoriasis) has been used since the early twenties. However, ultraviolet light is an ionizing radiation, and therefore has a damaging potential for biomolecules and has to be used in photomedicine with certain precautions. 
Biological and healing phenomena induced by optical wavelength (visible) and infrared (invisible) light have been intensively investigated in the last decade. Electromagnetic waves with optical (visible light) and near infrared (invisible irradiation) wavelengths (.lambda.=400-2,000 nm) provide non-ionizing radiation and have been used in vivo, in vitro and in clinical studies, as such radiation does not induce mutagenic or carcinogenic effects. 

Low energy photon therapy (LEPT), also known as LED photobiomodulation, is the area of photomedicine where the ability of monochromatic light to alter cellular function and enhance healing non-destructively is a basis for the treatment of dermatological, musculosketal, soft tissue and neurological conditions. 

Low energy photons with wavelengths in the range of 400nm-2,000 nm have energies much less than ultraviolet photons, and therefore, low energy photons do not have damaging potential for biomolecules as ionizing radiation photons have. 

The area of LEPT research is controversial and has produced very variable results, especially in clinical studies. Almost every mammalian cell may be photosensitive, e.g. could respond to monochromatic light irradiation by changes in metabolism, reproduction rate or functional activity. Monochromatic light photons are thought to be absorbed by some biological molecules, primary photoacceptors, presumably enzymes, which change their biochemical activity. If enough molecules are affected by photons, this may trigger (accelerate) a complex cascade of chemical reactions to cause changes in cell metabolism. Light photons may just be a trigger for cellular metabolism regulation. This explains why low energies are adequate for these so called "photobiomodulation") phenomena. However, it is difficult to induce and observe these phenomena both in vivo and in vitro using the same optical parameters. Specific optical parameters are required to induce different photobiomodulation phenomena (Karu, Health Physics, 56:691-704, 1989; Karu, IEEE J. of Quantum Electronics, QE23:1703-1717, 1987). The range of optical parameters where "photobiomodulation" phenomena are observed may be quite narrow. The specificity and narrowness of the optical parameters required for "photobiostimulation" in LEPT therapy distinguishes LEPT therapy from the photodestruction phenomena induced by hot and mid power lasers (e.g. in surgery and PDT). 

To meet the changing requirements for optical parameters for different experimental and clinical applications, there is a need for an optical system for "photobiomodulation" having flexible parameters, adjustable for particular applications. In particular, there is a need for an apparatus capable of treating a range of biological disorders by reliably providing light to the affected three dimensional biological tissue, which light has the optical parameters necessary for inducing the appropriate photobiomodulation for the particular disorder and tissue to be treated. There is also a need for a method for reliably providing light having such parameters to a biological tissue having a disorder in order to effect healing.

Intensity (Power Density) 

Intensity is the rate of light energy delivery to 1 cm.sup.2 of skin or biotissue. Intensity is measured in milliwatts per cm.sup.2 (mW/cm.sup.2). Real intensity on the skin surface depends on light reflection and scattering from the skin and underlying tissue layers. The light intensity on the skin surface can be calculated with the following formula 

I=(I-R).times.4.times.P/.pi.d.sup.2 (3) 

where P (or Pav for pulsed mode) is the optical power, d(cm) is the beam diameter and R is the reflection coefficient. Coefficient R can vary from 0.4 up to 0.75 for different wavelengths and depends also on the skin type and condition. For applications using non-contact techniques a portion of the optical power (and dose) equal to R.times.P is lost because of the reflection. Back scattering has to be taken into account for LEPT dosimetry as well. For contact technique applications, less power is lost due to the repeating light reflection back to the skin surface from optical source parts. Therefore, for the same optical source LEPT dosimetry would be different depending on the type of technique used (contact or noncontact). Particular "photobiomodulation" phenomenon can best be activated within narrow ranges of parameters (e.g. see Tables 2, 5, which appear later in this description). For example, collagen type 1 production is thought to be affected by LEL in an inverse manner to fibroblast proliferation: when cell proliferation is increased, collagen type 1 production is decreased and vice versa (van Breugel and Bar, 1992, Laser Surg. Med. 12:528-537). In cell culture experiments thin cell layers are usually uniformly exposed to light therefore intensity does not change significantly within the sample. For biotissue stimulation, the whole picture is different because light intensity (and dose) decreases with depth z. In the skin and subcutaneous tissue layers light intensity can be approximately described by the following formula (Beer's law): 

I(z)=I.sub.o (I-R)exp(-.alpha.z) ##EQU1## 

where I(z) (w/cm.sup.2 or mw/cm.sup.2)--is the fluence rate (intensity or power density) at the depth z (mm); I.sub.o =P/S--incident intensity; P--beam power; S=.pi.d.sup.2 /4 is a beam area for a cylindrical parallel beam of diameter d (cm); and .alpha. (mm.sup.-1) is the attenuation coefficient which depends on light absorption and scattering. This formula may be used to calculate intensity and dose for every particular tissue layer. 

Suitable intensities for biostimulation are in the range of from 0.1 to 5,000 mW/cm.sup.2. For stimulating healing of chronic ulcers or wounds intensity may preferably be in the range of from 0.2 to 10 mW/cm.sup.2, for ulcers or wounds in acute inflammatory stage a preferred range is from 10.0 to 30 mW/cm.sup.2 and for infected wounds a preferred range is from 50 to 80 mW/cm.sup.2. Table 2 below shows suitable ranges of intensities for different tissue pathologies. 

Beam Diameter and Divergence 

Beam diameter and divergence are important features of single optical sources. Beam size affects light intensity values on the skin surface and within the tissue in accordance with formulae (3, 4). Beam divergence affects light distribution and dosimetry for different tissue layers. For non-contact techniques light spot size and irradiated area S on the skin surface depend on the distance to the irradiated surface h as follows: 

S=.pi./4.times.(d+2h.times.TAN .alpha.).sup.2 (5) 

where d is the beam diameter near the probe tip, 2.alpha. is the diverging angle, 2h.times.TAN .alpha. is the additional beam diameter due to beam divergence. 

Different optical sources (lasers, laser diodes, light emitting diodes, etc.) have different beam divergences. Lasers usually have small beam divergency, laser diodes and LED's have bigger divergences. For different applications particular beam divergences are more convenient. For example, for the treatment of wounds and ulcers, almost parallel beams are less desirable because of the large areas to be treated, and optical sources with some particular divergence are more convenient. 

The beam diameter and divergence should be selected based on the three dimensional size and shape of the tissue area affected. Preferably, the beam diameter and divergence should be selected such that the area receiving LEPT is just slightly larger in size than the area affected. The appropriate radius of the beam may be calculated by the following formula: 

(R+1).sup.2 /R.sup.2 

where R (cm) equals the radius of the area affected by the disorder. In the case of lesions, such as ulcers or other open skin wounds, it is particularly important that too large an area not be illuminated as, where the illuminated area is much larger than the lesion, the skin ulcer (wound) healing rate is not optimized. As the ulcer is treated and healed the area requiring treatment and the beam diameter will have to be reduced. 


The dose D is the light energy provided to the unit of surface (1 cm.sup.2) during a single irradiation and measured in J/cm.sup.2 or mJ/cm.sup.2. The light dose received by the skin surface is 

D=I.times.t (6) 

where I is the intensity on the skin surface, and t is the exposure time (s). The dose received by subcutaneous tissue layer at the depth z for a parallel beam can be calculated by the following formula: 

D=I(z).times.t (7) 

where I(z) is given by formula (4). 

As mentioned above, the dose alone does not ensure particular photoeffect or healing phenomenon. Only proper selection of the whole set of optical parameters including dose will provide the desirable therapeutic effect. The selection of optical parameters depends on the medical condition, location of the affected areas, person's age, etc. 

Frequency and Pulse Duration 

Low range frequencies of 0-200 Hz may sensitize release of key neurotransmitters and/or neurohormones (e.g. endorphins, cortisol, serotonin). These frequencies correspond to some basic electromagnetic oscillation frequencies in the peripheral and central nervous system (brain). Once released these neurotransmitters and/or neurohormones can modulate inflammation, pain or other body responses. Analogous phenomena can be expected with "photobiomodulation" within the same range of low frequencies. Certainly, the interaction between living cell and pulsed electromagnetic wave depends on wavelength as well as pulse duration. Pulse repetition rates within the range 1,000-10,000 Hz with different pulse durations (milli-, micro- or nanoseconds) can be used to change average power. 

Three Dimensional Light Distribution 

Depending on the target tissue for LEPT (e.g. skin, muscle, ligament) a proper three-dimensional light distribution should be provided to get the desirable physiologic and therapeutic response. For single optical sources important parameters affecting light distribution are beam size, divergence, light wavelength as well as biotissue optical properties (reflection, absorption, scattering, refraction). Total reflectance is equal to the sum of the regular reflectance from the skin surface and the remittance from within the tissue (see FIG. 4). 

For cluster probes, additional contributive parameters are the distance between diodes and the cluster probe's three-dimensional shape. All these parameters should be physiologically justified to provide optimal biotissue response and requirable three-dimensional light distribution. For example, the distance between diodes can affect vasoactive blood vessel response and average energy density delivered to the treated area. For proper vasoactive response a definite distance between diodes has to be provided depending on particular parameters of a singular diode (power, beam, diameter, divergence). 

The three-dimensional light distribution in tissues such as the skin and underlying tissue layers may be calculated based on diffusion approximation and/or the Monte Carlo approach (L. Wang and S. Jacques, Hybrid model of Monte Carlo Simulation and diffusion theory for light reflectance by turbid media, J. Opt. Soc. Am. A/Vol. 10, No. 8, 1993, pp 1746-1752; A. Welch et al., Practical Models for Light Distribution in Laser-Irradiated Tissue, Lasers in Surg. Med. 6: 488-493, 1987). Wavelength 


Wavelength.lambda. (nm) is the basic electromagnetic wave feature which is directly linked to the energy of an individual light quantum (photon). The more wavelength the less photon energy. Wavelength is also linked to the monochromatic light color. Visible monochromatic light changes its color with wavelength, increasing from violet and blue (shorter wavelengths) to orange and red (longer wavelengths). Cell culture experiments have indicated that there is a selectivity in photoinduced phenomena related to wavelengths. Experiments on different cell cultures (microbe and mammalian) have revealed the ranges of wavelengths (360-440 nm, 630-680 nm. 740-760 nm) where photoinduced phenomena are observed (Karu, Health Physics, 56:691-704, 1989; Karu, IEEE J. of Quantum Electronics, QE23:1703-1717, 1987). Photoeffect can be induced by monochromatic light, only in cases, where a cell contains photoacceptors, substances which are able to absorb monochromatic light of this particular wavelength. No photoinduced cell phenomena can be observed if there are no wavelength specific photoacceptors in a cell. 

The following factors have to be taken into account when considering LEPT dosimetry for monochromatic light of a particular wavelength .lambda.. The dose required for "photobiomodulation" strongly depends on the wavelength. In general, the longer the wavelength the more dose is required to induce photoeffect. For example, in experiments on cell cultures, doses required for DNA synthesis stimulation are 10-100 times less with blue light (.lambda.=404 nm) than with red (.lambda.=680 nm) or near infrared (.lambda.=760 nm) light. 

Wavelengths in the range of from 400 to 10,000 nm may be used for LEPT, preferably from 500 to 2,000, more preferably from 600 to 1,100, most preferably from 600 to 700 nm and 800-1,100. There appears to be some optimal wavelength range to induce every particular photoeffect or healing phenomenon. For example, light having a wavelength of from 600 to 700, preferably from 630-680 nm, may be used for wound and ulcer healing. For chronic soft tissue pathology monochromatic light in near infrared wavelength range (800-1,100) is more suitable. 

Biotissue optical parameters (reflection, scattering, refraction, absorption and depth penetration) depend on wavelength. Therefore, light wavelength affects three-dimensional light distribution in biotissue. For example in a specific wavelength range, the longer wavelength the more light penetration depth. The darker skin the more light absorption, therefore the dose for a black skin has to be less then for a white skin. 

Monochromaticity (Bandwidth) 

Light source is described by its spectrum, which shows the range of wavelengths of the emitted light. Strictly monochromatic light source is a source of radiation with exactly the same wavelengths. This is never achieved in practice even with a laser. Every light source can be described by its spectrum bandwidth .DELTA..lambda.(nm). The smaller the bandwidth the more monochromaticity of the light source. The following considerations are important in regards to light source monochromaticity. 

Biological objects became adapted to wide-band solar radiation through evolution. Therefore, pronounced photoinduced phenomena in living cells can be observed only under irradiation by a light source with narrow enough bandwidth. The exact restrictions on light bandwidth may differ for various biological objects. 

Simultaneous irradiation by wide bandwidth and monochromatic light can lead to decrease or even disappearance of "photobiomodulation" effect. Therefore, it is recommended to provide some LEPT treatments in a darkened room. 

Difference in wavelengths emitted by optical source is leading to dispersion in light reflection, scattering, refraction and absorption which can affect three-dimensional light distribution and LEPT dosimetry. 

Bandwidth of the optical source can affect optimal intensity and dose values required to induce a particular healing phenomenon. The full bandwidth of monochromatic light to activate healing phenomena should not exceed 30-40 nm. 

Michael Braukus
Headquarters, Washington
(Phone: 202/358-1979)

Jerry Berg
Marshall Space Flight Center, Huntsville, Ala.
(Phone: 256/544-0034)
November 13, 2003
RELEASE : 03-366
NASA Light-Emitting Diode Technology Brings Relief In Clinical Trials
A nurse holds a strange-looking device, moving it slowly toward a young patient's face. The note-card-sized device is covered with glowing red lights, but as it comes closer, the youngster shows no fear. He's hopeful this painless procedure using an array of lights will help ease or prevent some of the pain and discomfort associated with cancer treatment. 

The youngster is participating in the second phase of human clinical trials for this healing device. The first round of tests, by Medical College of Wisconsin researchers at Children's Hospital of Wisconsin in Milwaukee, was so encouraging doctors have expanded the trials to several U.S. and foreign hospitals. 

"We've already seen how using LEDs can improve a bone-marrow transplant patient's quality of life," said Dr. Harry Whelan, professor of neurology, pediatrics and hyperbaric medicine at the Medical College of Wisconsin. "These trials will hopefully help us take the next steps to provide this as a standard of care for this ailment." 

The light is produced by light emitting diodes, or LEDs. They are used in hundreds of applications, from electronic clock displays to jumbo TV screens. 

LEDs provide light for plants grown on the Space Station as part of commercial experiments sponsored by industry. Researchers discovered the diodes also had many promising medical applications, prompting NASA to fund this research as well, through its Marshall Space Flight Center in Huntsville, Ala.

Biologists have found that cells exposed to near-infrared light from LEDs, which is energy just outside the visible range, grow 150 to 200 percent faster than cells not stimulated by such light. The light arrays increase energy inside cells that speed up the healing process. 

In the first stage of the study, use of the LEDs resulted in significant relief to pediatric bone-marrow transplant patients suffering the ravages of oral mucositis, a common side effect of chemotherapy and radiation treatments, according to Dr. David Margolis, an associate professor of pediatrics at the Medical College, working with Dr. Whelan on the study at Children's Hospital.

Many times young bone-marrow transplant recipients contract this condition, which produces ulcerations in the mouth and throat, severe pain and in some cases, inflammation of the entire gastro-intestinal tract. Chewing and swallowing become difficult, if not impossible, and a child's overall health is affected because of reduced drinking and eating.

"Our first study was very encouraging, and using the LED device greatly reduced or prevented the mucositis problem, which is so painful and devastating to these children," said Whelan. "But we still need to learn more. We're conducting further clinical trials with larger groups and expanded control groups, as required by the U.S. Food and Drug Administration, before the device can be approved and available for widespread use." 

The treatment device was a 3-by-5-inch portable, flat array of light-emitting diodes. It was held on the outside of a patient's left cheek for just over a minute each day. The process was repeated over the patient's right cheek, but with foil placed between the LED array and the patient, to provide a sham treatment for comparison. There was no treatment of the throat area, which provided the control for the first study. 

The researchers compared the percentage of patients with ulcerative oral mucositis to historical epidemiological controls. Just 53 percent of the treated patients in the bone-marrow transplant group developed mucositis, considerably less than the usual rate of 70-90 percent. Patients also reported pain reduction in their mouths when compared to untreated pain seven days following bone marrow transplant.

The clinical trials are expected to take approximately three years with a total of 80 patients. Participants currently include the Medical College of Wisconsin in Milwaukee; Roswell Park Cancer Institute in Buffalo, N.Y.; and Instituto de Oncologia Pediatrica, in Sao Paulo, Brazil. Other domestic and international hospitals have asked to join the multi-center study.

Quantum Devices of Barneveld, Wis., makes the wound-healing LED device. The company specializes in the manufacture of silicon photodiodes, or semiconductor devices used for light detection, and light emitting diodes, for commercial, industrial and medical applications. 

Supporting materials, including photographs, for this release are available on the Internet at:



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