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Done For You: How to Copy a Light Therapy Study (Part III)

How long should I use my red light?
How long should I use my red light?

You might be confused  about how long to use your light, what distance it should be from you, and how often to do sessions. The scientific data grows every day, but we don’t yet have standard, rule of thumb dosing for red light therapy. This section of the website is here to help you use YOUR light therapy device to copy successful light therapy studies.

In this section I list successful studies, as well as treatment time per session using various red light therapy devices. For example, researchers did a study red light study significantly reducing the subjects’ acne lesions.  They used 635 nm wavelength light delivering 20 joules/cm^2 for two sessions per week, for four weeks. Now you want to copy this study, but you don’t know where to begin. That’s what I’ll teach you below.

Learn to copy the successful acne reduction study using your red light therapy device
Learn to copy the successful acne reduction study using your red light therapy device

This is Part 3 of 3.

Use a Recommended Lamp to Copy a Successful Treatment at Home

If you have a GembaRed Spazer or GembaRed SAIDI red light therapy device, and you want to copy the acne reduction protocol used in the study below, then:

  1. find your device in the table
  2. decide how far to hold the device from the target
  3. read across to the “time per session”

Along with the number of treatments per week, and the number of weeks per protocol, you will now have everything y ou need to copy the study’s protocol using your device.

In Study Information, record the:

  1. Treatments per week
  2. Weeks per study

Find your device:

  1. Decide how far to be from your device
  2. Find the instructions for the time per session at that distance

The Study to Copy

Study Treatment Goal

Reduce acne vulgaris lesions

Study Joules/cm^2


Study Treatments per Week


Weeks per Study


Study Wavelength

630-700 nm

GembaRed Spazer light therapy device

Translate the study above to the GembaRed Spazer Handheld Panel

Light Therapy Device

EMF Channel Device Profile

The Spazer's Irradiance at a Given Distance

Time using the Spazer to get the 20 J/cm^2 dose in the acne study

68 mW/cm^2 irradiance at zero inches

Use the Spazer for 54 seconds at zero inches

28 mW/cm^2 irradiance at 1 inch

Use the Spazer for 11 minutes and 54 seconds at 1 inch

25 mW/cm^2 at 3 inches

Use the Spazer for 13 minutes 20 seconds at 3 inches

13 mW/cm^2 at 6 inches

Use the Spazer for 25 minutes and 39 seconds at 6 inches

gembared saidi red light therapy device

Translate the study above to the GembaRed SAIDI Handheld Panel

Light Therapy Device

EMF Channel Device Profile

The SAIDI's Irradiance at a Given Distance

Time using the SAID to get the 20 J/cm^2 dose in the acne study

48 mW/cm^2 at 1 inch

Use the SAIDI for 6 minutes 57 seconds at 1 inch

26 mW/cm^2 at 3 inches

Use the SAIDI for 12 minutes 49 seconds at 3 inches

14 mW/cm^2 at 6 inches

Use the SAIDI for 23 minutes 49 seconds at 6 inches

Is Your Light Therapy Device on Our List?

Each lamp has its own wavelengths and power densities. So we have to figure out the protocol based on what your lamp can do. If you use a red light therapy device I include the in the dose tables, just copy the dose where your light is listed.

Here are the studies I’ve documented so far. If you want to copy the protocols in one of these studies, click the link for that study, and see if your light therapy device is listed there. If it is, use the instructions for your light to copy that study’s protocol. If it is not, continue reading this article.

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My Light is Not on the List

If you want to copy a study but don’t have one of the lights listed, we need to calculate your treatment time per session based on your light’s specifications. I will show you how to calculate treatment time per session below.

How to Calculate Your Treatment Time per Session

The information I need from you is:

  1. your lamp’s wavelengths
  2. your lamps irradiance

Light Therapy Wavelengths

The wavelengths are the numbers that end in “nm,” such as 635 nm, which is a shade of red. “nm” stands for “billionths of a meter.” A 635 nm light is a one with a distance of 635 billionths of a meter between each wave peak.

Your lamp must have the wavelength used in the study you want to copy.  If your lamp’s wavelengths are NEARBY to the study’s wavelengths, you can still copy the study. You’re safe within 20 nm either way. So if the study calls for 635 nm, and your lamp is 650 nm, you can still use your lamp to copy the study’s treatment parameters.

Get Your Light’s Irradiance

Your lamp outputs photons. If you put the lamp on your body, we say it is “zero inches” from the target. If the lamp is a foot away, we say it is “12 inches” from the target.

The lamp outputs the same amount of photons at zero and twelve inches away. But your body receives MANY MORE PHOTONS at zero inches than it does at twelve inches. You get a bigger dose of energy when the light is close, and a smaller dose of light when the light is farther away.

So we need to know the power output of the light, and we need to know the distance the light will be from your body.

You get maximum photons when the lamp is zero inches away. Even one inch distance causes a drop off in how must energy you receive.

Get Your Light’s Power Density

Power density is how much energy the light emits onto a square centimeter of the target. Whether the lamp is right on the body (zero inches away) or 20 feet away, it emits the same power density. Power density describes the light’s output power, not input power. When you see something like “600 watts,” that’s how much energy it takes from the wall outlet to run the lamp. It is the input power, not the power density.

If a lamp can output 55 milliwatts of photons to a one square centimeter target in one second, we express it like this:

55 mW/cm^2

We don’t know from that notation how much energy your body absorbs. We just know how much the lamp can output. The “per second” is implied, it’s usually not written out.

Irradiance is Power Density at a Specific Distance

The irradiance we need to get from your light’s information is how powerful it is at a given distance. For example, this is how to express that the body receives 55 milliwatts of photons per second in a one square centimeter spot on the target when the lamp is 3 inches from that target.

55 mW/cm^2 at 3 inches

The “per second” part is almost always left off, but it’s implied. The 55 mW is 55 milliwats of energy. The cm^2 is square meter. So an irradiance of 55mW/cm^2/second at 3 inches says: if you hold this lamp at 3 inches from the target, the it will send 55 milliwatts of energy per second to a square centimeter of the target.

Get the Irradiance from Your Lamp Vendor

Hoepfully you can get the light’s irradiances from the vendor’s website, or from the literature that came with your lamp. This can be tricky because some vendors do not really understand light therapy dosing. They either do not publish the irradiance or they OVERSTATE it to make their lamps sound stronger than they really are. This is a probelm in the light therapy industry.   This is why I encourage readers to buy light therapy devices from vendors who publish the lamp irradiance values.

With the luck of having purchased from a knowledgable vendor, you should now have your lamp’s wavelengths and irradiance values. Now you will calculate your treatment time per session so you get the same joules (photon energy) as the subjects did each session.

Sample Lamp and Study to Copy

Let’s make an example to show you how it’s done.

  • Assume your lamp outputs wavelengths of 635 nm and 850 nm.
  • Further assume that it has an irradiance at zero inches (on your skin) of 48 mW/cm^2.
  • The study we want to copy treated each subject with  20 J/cm^2  (joules) of 635 nm light each session
  • Researchers treated subjects 2 times per week, for 4 weeks.

We now have everything we need to use the calculator to determine your dose time. Take these two values to the calculator:

  1. You confirm that your lamp has a 635 nm (or nearby) wavelength
  2. Go to the treatment time calculator.
  3. Enter the 48 from the 48 mW/cm^2 power density in the mW box
  4. Enter the 20 from the 20 J/cm^2 per session in the Joules box

The calculator will tell you that each session should be 7 minutes long.

  1. each session is 7 minutes
  2. hold the lamp directly on your skin (zero inches)
  3. do 2 sessions per week
  4. do four weeks of sessions total

See if Your Device is Here

Check the articles below to see if there’s a study you want to copy, and if I’ve documented how to use your specific light to copy that study’s protocols. If you find your lamp in the table, use the table’s information to determine:

  1. the length of each session
  2. the distance of the lamp from the target
  3. how many sessions a week
  4. how many weeks per treatment period