LED Light Therapy

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Introduction

Red and near-infrared light immediately relieve pain and speed healing. This is not bad science or a new-age flakey thing. I was first told about it by an orthopedic surgeon way back in 2000. He said "It's going to be huge." He was trying to get me interested in "low-level laser therapy", but I ignored it because I thought it sounded really flakey. Light doesn't even penetrate the skin, right? Wrong.

Red and near-infrared light are in a "window" of wavelengths that are able to pass through tissue up to 1 inch deep (not 6 inches like some web sites claim). Eventhough it goes only 1 inch deep, I am getting excellent feedback from those with knee and shoulder injuries. Red and near-infrared have beneficial effects on cells by "kick-starting" them into immediately creating more ATP (cellular energy) and increasing DNA and RNA activity. This effect has been carefully measured in many experiments since 1987. The positive effects occur in injured cells, but there is no benefit to healthy cells. In the past, lasers were thought to be needed to provide the light, but it's been known since 1989 that LEDs provide the same benefit. The ideal wavelengths are 610-625, 660-690, 750-770, and 815-860 nm (see below).

LED light arrays are a means to provide the best wavelengths. A company may claim that lasers and pulse rates are important, but the only important things are the total amount of light energy and the proper wavelengths (for example, 880 nm is a bad choice). Bright noon-time summer Sun has half as much light energy as LED devices in the optimum wavelengths and it covers the entire body (which is great for those with fibromyalgia). The advantages of LEDs over sunlight are: 1) LEDs can be applied at any time, 2) LEDs require only one hour instead of two hours for injuries beneath the skin, 3) LEDs don't get you hot and they don't cause sunburn.

Halogen lights emit a spectrum of light that is very similar to sunlight (see this chart or this) but they have more unnecessary far-infrared heat and not as much UV. Like bright sun, halogen provides an inexpensive source of "healing light energy" in the 600 to 900 nm wavelengths, but not at the best specific wavelengths as LEDs.

Heat lamps have long been used to reduce pain. It was usually believed the heat was what was beneficial. Now we know the near-infrared portion of heat lamps may provide the greatest benefit, despite the problems caused by too much heat in the far-infrared.

Conditions and Injuries Helped by LEDs

See the skin section for more information on wrinkles, spots, and acne. FDA allows advertising red and infrared for minor pains and mild arthritis. Red has been used to help halt wet macular degeneration but I don't know if it has FDA approval. The following have FDA approval for specific devices: infrared 880 nm for diabetic peripheral neuropathy, 660 nm red for mouth ulcers in children on a type of chemo, "Titan" intense infrared device for wrinkles in a clinical setting, very intense (harmful) infrared devices for spots, and blue or blue/red for acne. There may be other conditions that have FDA approval. I have heard excellent results for tendonitis, shoulders, knees, small joints, and fibromyalgia. For most soft-tissue injuries I've tested, I am generally told that the pain goes from an 8 to a 2 (on a scale of 10). Skin tissue seems optimized for healing, so that for healthy wounds closing good, LEDs do not seem to speed up the process very much in my experience, but some research disagrees. The pain relief can be amazing in burns, cuts, and other wounds even if wound healing is not faster. The benefits can be observed and the speed of healing can be measured in other living tissue in vivo like rabbit retina exposed to laser burns. I have not noticed any results for bruises. I have seen a small stubbed toe go from purple-black to pink in one treatment. 10 hours later, the purple returned and the LED turned it pink again. Serious injuries seem to benefit from 3 to 6 treatments/day (as the pain returns) instead of one treatment/day. Strangely, tendons sore from working-out seem to not receive any pain relief, but chronic tendinitis seems to benefit greatly. I have not see very good results in vertebra back pain or wound closure, but some research strongly disagrees with me. I've heard of scars disappearing, but I'm skeptical. Companies have made claims that I can't verify and don't believe: yellow for wrinkles, green for cancer, and blue for wrinkles. Most companies, doctors, and physical therapist are not using the devices long enough. For typical weak units sold on the internet, it requires an hour if the injury is beneath the skin and 3 minutes for shallow skin problems and up to 15 minute for deep skin. More than these doses per day WILL decrease and nullify the benerfits, although some very recent injuries can benefit from treatments being more than once a day.

From T. Karu, 1996 and 2005
The first and most important way is that we can provide injured cells with a larger amount of light in the beneficial range and at times when the sun is not available. The second is that we can reduce the heat and thereby provide higher concentrations that reach deeper cells (the sun is limited to about 1/2 to 1 inch of depth like most LED and laser units). Thirdly, in the future an inexpensive device will be made that is specifically tuned to the CCO set of proteins, having a specific sequence of pulse times of specific wavelengths and pauses, forcing CCO through each step of its pumping action with minimal heat and maximum depth.

A single wavelength may work as good as full spectrum by causing an electrostatic push or pull on neighboring electrons when moving only one electron (into or out of one of the two copper atoms in CCO). The electrostatic push and pull may cascade all the way through the electron transport chain. Indeed, complex II activity has been shown to increase even though it does not absorb these wavelengths.

Many different wavelengths have been used, but very few studies have compared different wavelengths. The figure above indicates wavelengths 610-625, 660-690, 750-770, and 815-860 nm are the best wavelengths. Considerations other than how well they activate CCO are: 1) which wavelengths penetrate the best (see section on absorption), 2) which LEDs provide the strongest light output (keep in mind 850 nm has 30% more photons per watt than 630 nm), and 3) possibly 630 nm being usefully absorbed and reflected as (aka "converted to") an 825 nm photon to be used again.

Inexpensive LEDs typically come in 630, 660, 850, and 880 nm with a hard-to-find (expensive) gap between 710 and 830 nm. The peaks of the LEDs and optimum wavelengths are not exact, but spread out about +/- ~10 nm so there is an overlap of available LEDs and the biologically optimum wavelengths. The 630 nm LED can affect the 620nm peak in the chart, and 660 nm LED touches the 680 nm peak, and 850 nm is directly on one peak, but does not cover the nearby peak 820-830 nm as well.

Ability of Light to Penetrate Tissue

Red and near-infrared light penetrate tissue because they are not blocked by blood or water as much as other wavelengths. A doubling of the light intensity at any particular wavelength will double the amount of light energy that reaches a particular depth. Also, doubling the time of application will double the amount of light energy. So if you use a device that is half as strong, you simply have to apply it twice as long. Skin, fat, and muscle all have different absorption and scattering coefficients that change depending on the wavelength which causes this to be a very difficult subject. Visible and infrared light does NOT travel through bone.

The question of what percentage of light is allowed through a particular tissue at a particular wavelength is very important, highly varied, and very complex. For example, there are 5 layers in the epidermis and dermis that have distinctly different absorption and scattering properties that change based on the location and color of the skin. All those variables change again based on the wavelength. An even bigger problem is that usable and reliable data to plug into the equations is non-existent. This is the situation for skin, which is always 1 mm or 1 to 4 mm thick, depending on which source you quote. I have a excel spreadsheet that tries to follow the methods of Steven L. Jacques and The Science of Phototherapy" but it's pretty much useless. Those sources state anywhere from 5% to 50% of the light in the 600-900 nm range is blocked by the epidermis and 5% to 95% is blocked by the dermis, and the only number for fatty tissue I have results in 99% being blocked by 1 cm.

The graph below shows that wavelengths over 900 nm start to get blocked more and more by water.

The graph below shows not much light is able to pass through oxygenated blood (HbO2) when the wavelength is less than 600 nm.

Below is the same data, but INVERTED and expanded in our area of interest.

To use the absorption coefficient to find percent of light transmission through blood, use T = 2.718^(-d*A) where d is depth in cm and A is absorption coefficient. This is simple absorption equation where light scattering coefficient is not taken into account (negligible for blood). If there is scattering, replace A with SQRT(3A(A+0.8S)) where S is scattering coeff and 0.8 is anisotropy assumption.

Below is another interesting graph that shows that each mm of melanin in skin is very effective at blocking light, but that layer is very thin (less than 0.005 cm) compared to the small fiber collagen and hemoglobin in the dermis layer (0.1 cm).

For the best info on HbO and Hb in blood see this. and also S Wray. Even if you understand the math, percent light transmission through tissue cannot be calculated unless you can find the %HbO and %Hb (or mM concentrations) in any particular tissue, along with the "baseline" (no blood) absorption and scattering of that tissue. Do that first and please email me the link(s).

Useful Charts:
Water Absorption Factors, 200 nm to 990 nm
Absorption Factor Chart

Comparing LED Wavelengths

660 nm verses 850 nm
Wavelengths greater than 800 nm penetrate tissue a little better than wavelengths shorter than 700 (see Light Penetration section). The effect is much larger in dark skin which will benefit more from 850 than from 660. The question is complicated by different wavelengths having stronger or different biological responses (see Optimum Wavelengths section). I don't know if one is better than the other, but I currently have a preference for 850 nm over all others. I am in the process of testing other wavelengths to see if I can find anything better than my best 850 device (shown below).

660 nm verses 630 nm
There is evidence that 630 could be as beneficial as 660. 660 nm will penetrate a little deeper because 630 is blocked more by blood and collagen. 630 nm red is slightly orange and 660 nm red is a "deeper" red. Since 660 nm is almost infrared, the human eye is not able to see it as well. 630 nm red is used in key rings, traffic lights, and car tail-lights because it's 6 times easier to see than 660 nm (see the photopic response factor - chart ). The eye doesn't suddenly stop sensing light at 700 nm, but it is a gradual decline in sensitivity. You might find some LEDs on key rings that appear brighter than 660 LEDs, but they are not putting out more light energy or having a larger healing effect.

880 nm verses 850 nm
There are some companies that claim 880 is "the best" frequency. I do not think that opinion is based on any scientific evidence. It appears 850 nm is able to put out more light energy with less heat compared to 880 nm. 880 LEDs are putting out frequencies in the range of 870 to 890 and are getting blocked 25% more by water absorption than 850. The biological response to 880 nm appears to be much less than at 850 nm (see Optimum Wavelengths section).

930 nm and above
It appears any wavelength longer than 930 nm will start to have too much of its energy blocked by the water in tissue. See the non-ablative part of the skin section for how 1000-1500 nm can be used to burn the color out of spot and have other beneficial effects.

Laser Light verses LEDs

There has been a lot of interest and money in low laser light therapy (LLLT) for healing, but there is no reason to believe that the coherent light from a laser is any better than LEDs, sunlight, or halogen lights. Laser light does not penetrate more deeply and cells do not know the difference: all photons are the same and the benefits are based on the action of each individual photon, not on bulk properties such as all the photons having the same polarity and coherency. The word "laser" has a superior marketing appeal for companies because it sounds interesting and mysterious. It also costs a lot which means patients can't do it on their own. These are the reasons there has been much more research in LLLT for healing than LEDs and halogens: companies and researchers have expected more profit. Light therapy is ancient and took on various new forms in the 1900's before lasers were invented. At least since 1989 definitive statements were being made in journal articles that lasers are not needed. To quote the most recognized researcher in LLLT, Professor Tiina Karu: "An analysis of published clinical results from the point of view of various types of radiation sources does not lead to the conclusion that lasers have a higher therapeutic potential than LEDs. ...The coherent properties of light are not manifested when the beam interacts with a biotissue on the molecular level....The conclusion was that under physiological conditions the absorption of low-intensity light by biological systems is of purely noncoherent (i.e., photobiological) nature....specially designed experiments at the cellular level have provided evidence that coherent and noncoherent light with the same wavelength, intensity, and irradiation time provide the same biological effect. Successful use of LEDs in many areas of clinical practice also confirms this conclusion." (Biomedical Photonics Handbook, 2003). Thankfully, Dr. Karu is a Russian Professor so we can expect her research to be more honest and scientific compared to U.S. medical research based on corporate profit. From a journal article: "...according to all available data, does not depend on the coherence of radiation." Reference: "Photobiological Principles of Therapeutic Applications of Laser Radiation" published by Yu. A. Vladimirov, et al in Biochemistry (Moscow) Volume 69, Number 1 / January, 2004.

Blue, Yellow, and Green

See the skin section for information about how blue can help acne (it's really violet, near UV-A) . Blue is about 430 to 485 nm. Green is 510 to 565 nm. Yellow is 570 to 590. None of these penetrate the deeper than the skin. See the skin section for how blue can help. There are some companies that claim yellow helps remove wrinkles. I haven't found any research that's not funded and conducted by the people who profit from it.

Design info: Comparing LEDs

Designers trying to select LEDs or arrays will have trouble comparing LED brightness from different manufacturers. The plastic encasings can focus the light and make mcd ratings much higher, but the amount of light coming out is the same. A 100 mcd LED at +/- 10 degrees (20 degrees angle of output) has the same total amount of light output as a 2,000 mcd LED at +/- 5 degrees (10 degrees). The equation is: Milliwatt output of an LED = mcd / (683 x P) x 2 x pi x (1-cos(1/2 Angle of output)). Companies are not exactly consistent in how they measure mcd (millicandela) and the angle output. Be careful in determining if they are stating 1/2 angle or full angle. P is the "photopic response factor" ( graph ) that depends on the wavelength. mcd and P are only meaningful for visible wavelengths (not infrared). P=1 for 555 nm and P=0.061 for 660 nm. For infrared, the measurement has to be mW/SR where SR=steradians. SR units are the percentage of a sphere's surface area, but divide SR by 4π (12.566) to get the percentage. SR is to a sphere as radians are to a circle. Replace mcd/(683 x P) with mW/SR for infrared LEDs. In practice all this is not very useful. You just have to buy the LEDs and compare them. All 850 nm LED lamps I've tested had the exact same efficiency. As a rough estimate, the light output energy of an LED is 30% of the input energy. Strong LEDs use 50 to 100 mA continuously. But 20 mA red LEDs can put out enough light and are very common. A good and strong 850 nm LED will use 50 mA continuously, but the device will get too hot if you pack the LEDs closely (22 LEDs per square inch for 5 mm packages) and run them anywhere near their max. 0.8 watts per square inch is the maximum energy you can apply to any device that touches skin unless a fan or heat sink is used in order to the skin temperature below 105 F (FDA guideline). Kind of like a high fever on the skin, except the blood is able to take away the heat. So at a typical spacing of 12 LEDs per in^2 (2 LED per cm^2) you can apply 66 mW per LED. That's 45 mA at 1.55 V for the common 850 nm lamp and 35 mA at 1.9 V for a good 660 nm. LED spectrums can be generated with this spreadsheet.

Despite all the above, in directly measuring LED strength as described below, I measure only half the intensity reported by the datasheets. Datasheets report very roughly 1/3 of the energy input coming out as light output. I measure only half as much, 1/6th.

You may think the following is crazy, so let me first say the results come out EXACTLY equal to the results expected for my quality assurance check, the Sun. So here it is: it's possible for anyone to directly measure the light intensity of something using a styrofoam cup, cocoa powder, and a home digital thermometer (accurate to 0.1 or 0.2 degrees C), based on the heat capacity of water. The equation is: mW/cm^2 = 2 cm x C x 4.18 / seconds where 2 cm is the depth of water with dark cocoa powder to make it black water, C is increase in the water's temp, 4.18 is converting from calories to Joules, and seconds is the time the light was applied (200 seconds works best for high power device, up to 600 seconds for typical low power). The styrofoam cup needs to be cut off at 3 cm and LEDs can't be too close because air currents cause direct heating from the LEDs. For LED devices too small to cover the surface of the water, apply the light for longer amount of time and multiply the results by the water surface area divided by the surface area of the LED array. Do not take temp measurements in the sun or while the LED device is being applied because the metal absorbs the light and heats up. Water temp must be exactly at room temperature, or more precisely, ending water temp should be above room temp by the same amount that beginning temp was below room temp. Using this direct measurement method, I typically get half of what LED manufacturer's spec sheets say and I know for self-consistency reasons that spec sheets are wrong. To calculate sun intensity at any time at any location on a sunny day, use this spreadsheet. I originally planned to use the Sun to calibrate this device and method, but it comes out so close to the predicted value for the Sun, no calibration or correction is needed.

Safety Concerns

Heat generation is the primary concern. Skin temperature should never be more than 41 C (105.8F) to meet FDA regs. There is no way to know how hot an array will get until it is wrapped as snuggly as possible. No matter how "cool" a heat-producing device operates, if it's wrapped good enough and long enough, it can get hot. It's not just how much energy goes in, but also how much goes out. I've found around 0.8 Watts per square inch to be the maximum energy that can be put into a device that touches the skin without a fan or special heat sinking. Eye Safety: Strong blue LED's are dangerous to your eyes! White LEDs have been studied for safety, but they have the harmful blue wavelengths in them. Strong green LEDs have 1/15th the risk of blue. Strong and focused Red and yellow LEDs appear safe, but I would not stare directly at them for more than a minute. A 10,000 mcd 660 nm red could be dangerous.

The following section has contradictions and will be improved at a later date

The ACGIH does not seem to have a safety factor based on time of exposure (TLV) for simple LEDs, but it has two categories that can apply to them. One is the TLV for laser light, but lasers are different because they focus the light in one spot which is much more likely to cause harm. The link at the bottom of this paragraph is a well-researched article that strongly claims you don't need to treat LEDs as lasers when it comes to safety. The other TLV is for light at a range of wavelengths and time exposures. Blue LEDs may harm the eyes from a photochemical injury called the "blue light hazard" that can cause loss of vision wherever the blue light strikes the retina. Distance from such a narrow-beam, strong blue LED only makes the AREA of damage on your retina smaller, not that damage is less likely to occur. Red, yellow, and green also have photochemical risks, but for LEDs, only green has the remote possibility of causing harm (if it's high power with a narrow emission angle). Bright visible light may also harm the retina from thermal activity. Blue is thermally 10 times more dangerous than the others. Reasonably powerful LEDs in red, yellow, and green are also thermally safe. But they are brighter at narrow wavelengths than we have evolved to cope with, so I still consider staring at them for more than a minute to be risky. Infrared light > 770 nm may harm the retina and lens from thermal activity, but has more risk for the lens. Damage to the lens may take the form mainly of cataracts. Infrared should be less than 10 mW/cm^2 if it's applied for greater than 15 minutes. For less than 15 minutes, mW/cm^2 should be < 1800 t^(-0.75). This means 83 mW/cm^2 is safe to the the lens for up to one minute. An excellent 50% efficient LED at its maximum power dissipation of 100 mW has 100x0.50=50 mW light output, but if you shine it directly on the eye, it's an exposure in an area of only about 5 mm in diameter, or 0.20 cm^2, so 50/0.2= 250 mW/cm^2 light intensity. So by using the TLV equation above, it appears up to 15 seconds is safe when shining one of the most powerful types of 5 mm infrared LEDs directly to the eye. So, it's possible to increase the risk of cataracts when treating macular degeneration with red and infrared LEDs. From another source: "Near-infrared thermal hazards to the lens (associated with wavelengths of approximately 800 nm to 3,000 nm) with potential for industrial heat cataract. The average corneal exposure to infrared radiation in sunlight is of the order of 1 mW/cm^2. By comparison, glass and steel workers exposed to infrared irradiances of the order of 80 to 400 mW/cm^2 daily for 10 to 15 years have reportedly developed lenticular opacities (Sliney and Wolbarsht 1980). These spectral bands include IRA (700-1400 nm) and IRB (1.4 �m-3.0 �m). In contrast to blue light, IR-A is very ineffective in producing retinal injuries (Ham, et al., 1982, 1976). The American Conference of Governmental Industrial Hygienists (ACGIH) guideline for IRA exposure of the anterior of the eye is a time-weighted total irradiance of 10 mW/cm^2 for exposure durations exceeding 1,000 s (16.7 min) (ACGIH 1992 and 1995). Pitts, et al. (1979) showed that the threshold radiant exposures to cause lenticular changes from IR-A were of the order of 5000 W*s/cm2." Note: For visible LEDs, Use L= 1000 x mcd/(683 x P) in place of L x (change in wavelength) in the TLV equations. For infrared, use mW/(SR x 1000). The distance from the LED does not change the danger for equations with L in them. The reason for this is because the ACGIH values each and every rod and cone in the retina, and light from a further distance has the same strength for each rod and cone it hits - it is weaker only because it affects a smaller number of them. See also retinal eye safety (but they don't address lens safety, do not give an mcd example for blue, and don't discuss focusing that new LED plastic cases use).

Halogen lights contain a lot of blue light and are very dangerous to the eyes.

Sunshine

Bright sun at midday in the southern U.S. in summer has as much energy in the red and near-infrared (600-900 nm) as LED arrays (about 29 mW/cm^2 - see chart below which has an error in saying '39'). But only about 50% of the light in the 600-900 nm range from the Sun is at the best wavelengths, so it requires mirrors and sunscreen to increase the amount of Sun to equal the best LEDs devices which have all their energy concentrated at the best wavelengths. If mirrors are not used, treatment time is doubled or tripled to get the same benefit as a good LED device, but then getting hot becomes a problem if you don't have a fan and a mist of water to keep cool.

Halogen, Incandescent, and Infrared Heat Lamps

The Sun, Halogen lamps, incandescent lamps, and infrared heat lamps all emit light based on the black body radiation principle (see this excel spreadsheet if you like physics). Halogen lamps have a curve half way between the ones shown for incandescent and the Sun (see this chart). The Sun has 29% of its energy in the 600 to 900 nm range and halogens have 28%. Incandescents have 15% to 21% and heat lamps have about 10%. Halogen, incandescent, and infrared heat lamps all heat up a metal filament of tungsten to produce light. The filament "incandesces" which means it produces light by black body radiation. The only difference is that a halogen gas can allow the filament to get hotter than regular incandescent bulbs and heat lamps have a cooler operating tungsten filament. They operate at approx the following temperatures: Sun - 5780 K, halogen - 4100 K, incandescent - 2800 to 3200 K, heat lamp - 2400 K. The cooler filaments emit more energy in the far-infrared which is easily absorbed by water which heats the water in the skin, concentrating the energy in a small volume of skin tissue that has pain and heat sensors. This is how operating at a lower temperature can produce a stronger feeling of heat in the skin.

In summary, halogen lamps will produce light like the Sun and it can provide more light energy in the healing (tissue penetration) range of wavelengths than regular incandescent and heat lamps. This will be much more energy than LEDs can provide and the energy will be spread out over a larger range of wavelengths (see chart above comparing LEDs and Sun). The halogen is closer to the Sun's natural spectrum. Halogen lamps usually have glass covers that block UV light so that desk lamps do not cause sunburn to hands. The strong blue wavelengths of halogens can be very harmful to the eyes. As with typical LEDs that have about 30% efficiency in converting power input to light output, and as with the wide-spectrum of the sun, halogen lamps also put out about 30% of the energy they use as light energy in the tissue penetration range. So a 50 W Halogen spot-light that concentrates it's light in a 10x10 cm area close to the bulb will produce 50*0.30/10^2= 0.16 W/cm^2 = 160 mW/cm^2 of light intensity in the tissue penetration range, but the heat from the far-infrared in the skin will be too powerful to keep it there for more than a few seconds. This is about 3 times the best LED array and 5 times the healing range of sunlight. To get as much light from a halogen as you can from very bright sun, simply compare the heat you feel from a halogen to the heat you would feel from the sun and the healing dosage should be about the same. Plexiglass can block some of the far-infrared that heats the tissue. Well-designed LEDs will not have the heat problem at all and are not supposed to be harmful to the eyes (I'm still researching it) which are two important reasons they are being used. LEDs are more powerful over a short range of wavelengths which appears to be just as beneficial as having the wattage spread over a wider range of wavelengths as occurs with halogens and the Sun. Here are more comments on using halogen lights.

Halogen lights contain a lot of blue light and are very dangerous to the eyes.

Does Pulsing LEDs Help?

Some companies claim pulsing the light is important, but i haven't seen any data to support it. Pulsing increases the light at all depths for a brief period of time. But a constant light source can provide the same amount of total light energy per minute when operated at lower intensity. Pulsing probably does not provide more light per minute to the deeper tissue. 50 mW/cm^2 applied for half a second during each second of application will not provide more light at 1 cm depth than 25 mW/cm^2 applied for the full 1 second. It generates the same amount of heat. There are four ways pulsing may help:

If there is a "light power threshold effect" in cells. By this I mean there could be something in tissue that requires a certain amount of "activation energy" to cause a reaction to occur. But there is no research to support this.
If there is something interesting in tissue that responds to certain rates of pulsing. It would take an enourmous amount of clever research to determining what kind of pulsing is best (duration, waveform shape, and/or pauses).
By flooding absorption sites in shallow tissue with short strong pulses, there may be a higher percentage of light energy available to deeper tissue.
Pulsing may reduce some sort of instantaneous local heating of the LED chip that improves efficiency

In summary, I know of ways it MAY help, but I do not have any data to support the idea. I have seen 2 web sites claim that pulsing makes the LEDs more efficient, but the light output verses power input curves I have seen for typical LEDs indicate that being constantly on at a lower power input is slightly more efficient, probably due to having a lower operating temperature. If an LED is pulsed it has to have higher current to generate more light during the pulse to compensate for being off half the time and this could decrease efficiency, but item 4 above could still have larger positive effect.

Skin: Wrinkles, Acne, Scars, and Spots

Light devices that you can use at home are probably not going to reverse the signs of aging...at least not very much. Red and infrared light helps injured cells a great deal, but wrinkles and scars are not injured cells. I found only one journal article (see below) that indicated simple red and infrared light energy can help. Please email me if your skin has benefited from something you can use at home.

Low Power Devices for wrinkles and aging:

This article reported red (633 nm at 126 J/cm^2) and near-infrared (850 nm at 66 J/cm^2) for two treatments per week for 5 weeks resulted in 67% of the patients reporting good to excellent results. Using sunscreen and two mirrors, you can face the noon-time summer sun for 1 hour 4 times a week to get the same treatment. An $8 PAR38 75 W halogen light from WalMart can also do it in an hour for one side of the face.
There's an FDA-approved "Titan" device that uses strong infrared to tighten skin, available only through a doctor.
I saw an article claiming pulsed blue was good for wrinkles, but the research was so bad, I'm not providing the link.
See also non-ablative below (medium power devices that require a doctor visit)

Acne: Researchers (Tremblay, Morton) have used 48 J/cm^2 (20 minutes of 40 mW/cm^2) of 415 nm blue to treat acne vulgaris twice a week for 4 weeks (mild to moderate cases, propionibacterium acnes, but not Staphylococcus epidermidis). They call it "blue" but it's really a violet that borders on UV-A. It would take 2 hours of the brightest sunlight without sunscreen (or one hour by using a mirror to double the light intensity) to equal the one of these 20 minute treatments. Alternating red 633 nm once a week with blue 415 nm once a week may have worked better "particularly for papulopustular acne lesions" for mild to severe cases as reported by DJ Goldberg and SY Lee. P Papageorgiou used 415 nm and 660 nm. Doses were always about 48 J/cm^2 for blue up to 100 J/cm^2 for red. I would expect better results if they had used the red everyday and the blue twice a week, in addition to plenty of sunlight.

Spots:

Non-ablative devices are not as serious in terms of risk as ablative (destructive) and they may soon be as good as the older ablative techniques. The non-ablative devices usually use high-energy focused spots of laser light that cannot be duplicated by LED devices sold on the Internet. Wavelengths from 500 to 3000 nm (blue to mid-infrared) have been used, but 1000 to 1500 is being researched the most. These techniques are improving, but are still not as good as ablative. Usually, between >1000 nm and < 1500 nm wavelengths, long or short pulsed, are used to heat the water in the skin to cause heat damage to the cells. Therefore this technology is much different than the 600-900 nm healing wavelengths that the rest of this page is concerned with. Studies have used three to eight treatments typically one month apart. Cryogenic cooling may also be used to minimize harm. At Reliant Technologies, the ablative areas are a about 0.5 mm deep into the skin and twice as thick in diameter as a human hair. "Fractional rejuvenation" or "fractional photothermolysis" is the non-ablative version of the grid pattern used in ablative techniques.

Fractional photothermolysis (FP) has been recently introduced as a new concept in dermatologic laser medicine. FP employs an array of small laser beams to create many microscopic areas of thermal necrosis within the skin called microscopic treatment zones (MTZ). Even though FP completely destroys the epidermis and dermis within these MTZ, the 3-dimensional pattern of damage heals quickly and with few side effects. FP is currently used to treat fine wrinkles, photodamaged skin, acne scars, and melasma. Due to its clinical efficacy and limited side effects FP has established itself in the past two years as an alternative treatment modality to the conventional ablative and non ablative laser therapy. 2007 German article

And here's another review from 2006:

Ablative lasers (CO2 and Er:YAG) provide the greatest improvement in photoaging, but significant adverse effects limit their use. Nonablative lasers have reduced adverse effects, but limited efficacy. Fractional photothermolysis (FP) produces arrays of microscopic thermal wounds called microscopic treatment zones (MTZs) at specific depths in the skin without injuring surrounding tissue. Wounding is not apparent because the stratum corneum remains intact during treatment and acts as a natural bandage. Downtime is minimal and erythema is mild, permitting patients to apply cosmetics immediately after treatment. As with other nonablative laser modalities, multiple treatments are required. FP represents an alternative for treatment of dermatologic conditions without the adverse effects of ablative laser devices and can be used on all parts of the body. FP can be used for the treatment of facial rhytides, acne scars, surgical scars, melasma, and photodamaged skin.

To quote an outdated 2002 MedScape article to show the initial skepticism of non-ablative techniques 6 years ago:

Unfortunately, clinical data in support of nonablative lasers and light sources [including LED devices] for wrinkle and acne scar treatment remain unimpressive. Despite a series of lectures and dozens of research presentations dedicated to the subject, results at this year's ASLMS often failed to impress the audience. Some before-and-after slides elicited puzzled expressions, while others triggered sporadic laughter. As one attendee murmured during a presentation, 'I can't tell any of the befores from the afters.'

Since this quote, many postive articles have been published. One study used 14 J/cm^2 with a 0.3 ms short pulse at 1064 nm for improving scars. Another used a combination of blue and infrared: 7 to 15 J/cm^2 with 7 to 50 ms pulses at 535 nm and 24 to 30 J/cm^2 with 30 to 65 ms pulses at 1064 nm. 1300 nm and 1500 nm lasers are also commonly used.

Ablative (destructive) energy levels use lasers (also not available to patients for home use) that can destroy uneven pigment colors and cause the skin to heal itself in a way that reduces wrinkles. They have a recovery period that has to monitored by a dermatologist. "Fractional resurfacing" is a new ablative technique that applies the destructive energy in a close grid pattern that is not continuous, but alternates between harmed (ablated) and unharmed sections of skin. The unharmed cells help heal the adjacent ablated cells faster and better. More than one treatments can be used.

Misc Comments

In hindsight, we can say "people have always known sunlight is good for you". It seems intuitively clear to most people that sunlight helps sick people and enables people to be more active. Now we know why from a chemical and biological viewpoint. Injured cells need the extra ATP, etc to repair themselves. Healthy cells generate enough ATP from the red and near infrared of sunlight to enable more activity. If the ATP is not used (as occurs when resting in bright sunlight) it causes an increase in available glucose for which causes a slight "glucose high" that causes relaxation and sleepiness we all feel after 30 minutes in the sun. We know UV creates vitamin D that prevents colon, prostate, and breast cancer and greatly improves the immune system and bone strength. Skin cancer from UV is not a significant problem compared to the benefits of UV. The current fear of UV may cause more cancer than it prevents. 10 minutes a day of strong UV from summer sunlight is safe and the best source of vitamin D.

Effects of LED Light Therapy - Highlights of Journal Articles

"But if the rats were treated with LED light with a wavelength of 670 nm for 105 seconds at 5, 25 and 50 hours after being dosed with methanol, they recovered 95 per cent of their sight. Remarkably, the retinas of these rats looked indistinguishable from those of normal rats. 'There was some tissue regeneration, and neurons, axons and dendrites may also be reconnecting,' says Whelan."

"We believe that the use of NASA Light-Emitting Diodes (LED) for light therapy will greatly enhance the natural wound healing process, and more quickly return the soldiers to a pre-injury/ illness level of activity. The use of LED in combat with self-healing patches in future may enable the soldiers even after they are wounded to persist in combat better and longer."
http://www.asc2002.com/Abstracts_only/d/DA-06.pdf

"LED produced improvement of greater than 40% in musculoskeletal training injuries in Navy SEAL team members, and decreased wound healing time in crew members aboard a U.S. Naval submarine. LED produced a 47% reduction in pain of children suffering from oral mucositis. CONCLUSION: We believe that the use of NASA LED for light therapy alone, and in conjunction with hyperbaric oxygen, will greatly enhance the natural wound healing process, and more quickly return the patient to a preinjury/illness level of activity. " "ATS treatments improve sensation in the feet of subjects with DPN, improve balance, and reduce pain."
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=11776448

"This technology may be the answer for problem wounds that are slow to heal....diabetic skin ulcers and other wounds in mice healed much faster when exposed to the special LEDs in the lab. Laboratory research has shown that the LEDs also grow human muscle and skin cells up to five times faster than normal...."

"Light close to and in the near-infrared range has documented benefits for promoting wound healing in human and animals. "
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=11568632

"ATS treatments improve sensation in the feet of subjects with diabetic peripheral neuropathy, improve balance, and reduce pain."
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&list_uids=14693984

"Near-infrared irradiation potentially enhances the wound healing process, presumably by its biostimulatory effects."
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&list_uids=11722751

" It was found that laser exposure resulted in more pronounced restoration of functional state of nervous fibers than conventional therapy. Application of laser irradiation of low intensiveness was effective while in combined therapy of distal diabetic polyneuropathy as well as monotherapy."
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&list_uids=9677693

"exposure of volunteers to visible and infrared polarized (VIP) light leads to a fast increase in the growth promoting (GP) activity of the entire circulating blood for human KCs in vitro, which is a consequence of the transcutaneous photomodification of blood and its effect on the rest of the circulating blood volume."
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&list_uids=14743286
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&list_uids=14521091

"The method of monochromatic near infrared stimulation can be used for selective stimulation of several regions of the external auditory canal,.."
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&list_uids=14999583

LED and LLL irradiation resulted in an increased fibroblast proliferation in vitro. This study therefore postulates possible stimulatory effects on wound healing in vivo at the applied dosimetric parameters.
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&list_uids=12928819

Wound healing was significantly more rapid with than without FIR. Skin blood flow and skin temperature did not change significantly before or during far-infrared irradiation.
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&list_uids=12773705

Although more studies are needed, LED therapy appears useful in the prevention of OM in pediatric BMT patients.
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi

News articles on the NASA Study:
http://garm.dyndns.org/whelan_lab/01/html/%20/whelan.html
http://www1.msfc.nasa.gov/NEWSROOM/news/releases/2000/00-336.html
http://healthlink.mcw.edu/article/975450257.html
http://www.hypography.com/article.cfm?id=29173
http://www.viahealth.org/via_news/news2002/april/woundstudy.htm
http://www.engr.wisc.edu/industry/atwork/vol5/WCSAR.html
http://www.scienceblog.com/community/older/archives/D/archnas202.html

A wound-healing device was placed on the USS Salt Lake City submarine, and doctors reported 50 percent faster healing of crewmember's lacerations when exposed to the LED light. Injuries treated with the LEDs healed in seven days, while untreated injuries took 14 days.

second daily infrared (JR) laser (820 nm, 25mW) and visible red laser (670 nm, 10 mW) at 1 J/cm2 and 5 J/cm2 on chronic pain. ...five treatment sessions over a two-week period. ...significant reductions in pain over the duration of the study with those groups which received infrared (820nm) laser a 1 J/cm2 and 5 J/cm2

904 nm three times weekly for 2 weeks, ......tendonitis of the shoulder

3.5-inch by 4.5-inch (89-millimeter by 114-millimeter), portable flat array of LEDs, arranged in rows on the top of a small box. ......places the box of LEDs on the outside of the patient's cheek about one minute each day. The red light penetrates to the inside of the mouth, where it seems to promote wound healing and prevent further sores in the patient's mouth.

All 176 patients received six treatments during a period of 3-4 weeks. ..GAAs laser therapy for tendinitis and myofascial pain

A 40 year-old woman presented at the Abe Orthopedic Clinic with a 2-year history of lower back pain and pain in the left hip and leg diagnosed as a ruptured disc between the 5th lumbar/1st sacral vertebrae. .....The gallium aluminum arsenide (GaAlAs) diode laser (830 nm, 60 mW) was used in outpatient therapy, and after 7 months, the patient's condition had dramatically improved, demonstrated by motility exercises. This improvement was confirmed by further MRI scans, which showed clearly the normal condition of the previously herniated L5/SI disc.

Influence of low-level (810nm, GaAlAs semiconductor) laser on bone and cartilage during joint immobilization was examined with rats' knee model. .......The hind limbs of 42 young Wistar rats were operated on in order to immobilize the knee joint. One week after operation they were assigned to three groups: irradiance 3.9W/cm2, 5.8W/cm2, and sham treatment. After 6 times of treatment for another 2 weeks both hind legs were

myofascial pain in the cervical region. The patients were submitted to 12 sessions on alternate days to a total energy dose of 5 J each.

RA:From July 1988 to June 1990, 170 patients with a total of 411 affected joints were treated using a GaAlAs diode laser system (830 nm, 60 Mw C/W). Patients mean age was 61 years

890 nanometer (nm)....Venous ulcers, diabetic ulcers, and post-amputation wounds....It recently has been demonstrated that application of this particular MIRE device to the skin for 30 minutes increases plasma NO in nondiabetic subject volunteers, as measured with a Sievers Instrument, Model 280, Nitric Oxide Detector

© 2008 heelspurs.com LLC
Author: Scott Roberts
scott@heelspurs.com

Index

Introduction
Conditions Helped
How Does It Work?
Device Strength
Optimum Dosage
Best Wavelengths
Light Penetration
LED Wavelengths
Laser vs. LED
LED Designers
Safety
Sunlight
Halogen and Heat Lamps
Pulsing LEDs
Skin: Wrinkles, Spots, Acne
Misc Comments
Journal Abstract Summaries

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