Scott Nelson

Why Device Size and Coverage Area are Critical for Effective Red Light Therapy

When it comes to medical-grade light therapy, the size of a device matters, which directly correlates to the coverage area during a treatment. The distance a person stands from a device is also a crucial variable that impacts how effective a light therapy treatment can be.

As red light therapy has grown in popularity, some manufacturers are unfortunately promoting misleading claims about cheap devices delivering enormous amounts of power that can allegedly treat your entire body. Many of these marketing pitches totally avoid key questions about coverage area and delivered power, and some make erroneous statements about how close you need to stand to a device to receive a relevant dose of therapeutic energy.

This article explains the importance of device size, coverage area, and distance—and also gives background on how light therapy power is measured. We include independent, 3rd-party diagnostic testing laboratory data and graphs that illustrate the importance of the aforementioned specifications.

Measuring Light Therapy Power and Dosage: The Basics

If you want to go in-depth on measuring light therapy power, this article has you covered and includes a lot of independent testing data on Joovv and competing devices.

Here are the basics:

Irradiance: The power of light is often measured in irradiance, or the power per unit area, usually defined in milliwatts per square centimeter (mW/cm2). In terms of light therapy, you can think of irradiance as the rate of energy delivered by a device. Unfortunately, unlike Joovv, some light therapy manufacturers don’t provide independent, verified power measurements. When they do, it’s usually just an irradiance number without any context, which definitely doesn’t tell the whole story. You want to know how a treatment will impact you, the human using it. Irradiance just measures the device output, not how much energy it’s delivering to you or how much area it’s actually covering.

How Medical Researchers Measure Light Therapy: Inexpensive solar meters that you can buy on Amazon (like the Megger PVM210) can provide some basic comparisons, but they aren’t sophisticated enough to give accurate power readings for clinical light therapy devices. Medical scientists and researchers who run clinical trials with light therapy devices go beyond simple irradiance and take into account how much surface area is covered by the light in order to calculate a more holistic measurement of total delivered power.

Harvard Medical School photomedicine researcher Dr. Michael Hamblin, a member of Joovv’s scientific advisory board, explains why total delivered energy is needed:

Total light energy is the most accurate and comprehensive way to measure the power of light therapy devices and treatments,” says Dr. Hamblin. “If you only account for irradiance—versus how much total energy a device delivers—you miss the larger picture of how light therapy positively benefits the person using it.

The Most Powerful Light Therapy: Independent testing from ITL laboratories, one of the most respected photodiagnostic companies in the world, shows Joovv delivers by far the most total energy among consumer light therapy products. As you can see in the table below, which compares several light therapy brands, Joovv’s devices also offer a much larger coverage area. This is a crucial variable that we’ll discuss in the following section.

Joovv Red Light Therapy Power Comparison

Crucial Light Therapy Treatment Variables: Coverage Area and Distance from the Device

Total light energy delivered is the metric that matters in light therapy, and you can’t measure that without accounting for crucial variables, especially the coverage/size of the treatment area, and the distance a person is from the device.

Size + Uniformity = Treatment Effectiveness

How much surface area the light covers on your body is vital to measuring the effectiveness of a light therapy treatment. You want to figure out how much energy the device will deliver to your body, not the power it can create in a vacuum.

Full-body red light therapy is ideal for overall health & wellness, and generally speaking, the more coverage you can get, the more photons of light are able to reach your body’s cells to help them produce more energy. Naturally, a light therapy treatment that stimulates the cells across your whole body is going to have more clinical effect than treating a small area like your elbow, regardless of how powerful the device might be. Uniform, full-body coverage is optimal for the best light therapy results.

As an analogy, think about comparing the sizes of two snowstorms. Storm A dropped 12 inches of snow, but it only hit one city. Storm B blankets an entire 5-state region with 8 inches of snow. Storm A produced the most snowfall in any one place (the most snow producing power, in a vacuum). But it’s pretty clear Storm B is bigger in terms of how much total snow it produced (total delivered energy).

The larger your device, the larger the coverage area. That increases the total energy you receive exponentially over a smaller device. It also equates to much shorter treatment times to get the same amount of therapeutic energy. With a full-body Joovv device, like the Quad or Elite, 10 minutes a day has you covered. To get the same power from a small device, you’d have to shine it on different parts of your body all day, resulting in non-uniform doses of energy and a frustrating user experience.

Distance from the Device is Key

You simply can’t get a biologically-relevant dose from a light therapy treatment if you’re standing too far away. Misleading claims from some manufacturers have confused a lot of people about this key point. You need to be close to a device to get a clinical dose of light, ideally 4-12 inches. You cannot experience real red light therapy if you’re standing several feet (or further) from your device.

To demonstrate this, let’s look at the hard numbers from the prestigious, independent diagnostics testing laboratory, ITL. Check out the graphs below showing how distance matters a lot when it comes to the energy your body can absorb from a light therapy treatment.

Device A is from one of the manufacturers that promotes the misleading claim of full-body coverage when standing 3 feet from their small device. As you can see, at 12 inches away, the irradiance falls off dramatically from 20 mW/cm2 to only 1 mW/cm2.

Device B is another good example. At just over 6 inches away, the irradiance drops from 5 mW/cm
2 to 1 mW/cm2

These devices don't come close to offering full-body coverage, and can't deliver effective therapy at all from a distance greater than a foot. 

Compare that to the Joovv Quad shown at the bottom. It's much larger than Devices A & B and provides far greater coverage & power when you stand 4-12 inches away. This makes it possible to get full-body effects with relatively short treatment times. But despite its size, you still can't stand several feet away from the Joovv Quad and expect to receive the same therapeutic dose of energy in the same amount of time. Distance matters when it comes to effective light therapy, no matter what the irradiance is.

Based on 3rd party analysis, it’s clear that the distance you are from a light therapy device is directly correlated to the energy your body receives. The further you’re away, the longer you’ll need to use the device to receive a clinically-relevant dose of energy.

Red Light Therapy Isoline Graphs

The biggest takeaway from this data is that the total energy your body receives from a light therapy treatment is a function of:

  • Size & Coverage: The size of the device and its coverage area on your body are crucial (more coverage=more energy=better treatment).
  • Distance: You need to be close to the device (more distance=less energy received=less therapeutic effect).

Joovv is Trusted by the Best

Joovv’s devices have made medical-grade, personal red light therapy a reality. Our light therapy products outperform the rest in all the independent tests of power, size, coverage, and energy delivery. But you don’t have to take it from us. Only Joovv is being used by pro sports teams & athletes, world-class trainers & elite gyms, clinics, spas, salons, and by the leading skincare & natural health professionals.

Joovv is trusted by the world’s best trainers, like Ben Greenfield, Lacey Stone, Jorge Cruise, and the late great Olympic strength trainer Charles Poliquin. See the full list of training & fitness pros using Joovv.

NFL stars like Keenan Allen and Patrick Peterson are Joovvin’, and so is UFC champ TJ Dillashaw, NBA teams, MLB & NHL, and pro soccer players, and Olympians. Check out the elite athletes using Joovv.

Joovv is also the trusted light therapy brand of natural health leaders like Dave Asprey, Dr. Sarah Ballantyne, Wellness Mama, and many more.

Conclusion: Size, Coverage, & Distance are Crucial for Effective Red Light Therapy

You just can’t get an accurate light therapy measurement if you’re not factoring in the crucial variables of device size, coverage area, and distance from the device, in addition to the irradiance/power a device can deliver.

Beware of light therapy manufacturers making big claims about power with cheap devices that don’t have the size to do the job or the independent data to prove their numbers are real. If you see images of a device shining light on a person who’s more than a foot away, those aren’t clinical treatments.

Joovv light therapy products are indicated for use in the relief of muscle and joint pain, including arthritis and muscle spasm pain, and increasing of blood circulation, and relaxation of muscles. The information provided in this article is for educational purposes only and is not intended to support the safety or effectiveness of Joovv devices, or diagnose, treat, cure, or prevent any disease. It's not a substitute for a face-to-face consultation with your healthcare provider, and should not be construed as medical advice.

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