Red Light Therapy

How It Works, Wavelength, Irradiance & Dose

Red light therapy, also called photobiomodulation (PBM) or low-level light therapy, uses specific wavelengths of visible red light from 620nm to 750nm to deliver energy to the body's tissues. Joylux uses the 620 nm wavelength because clinical research demonstrates that this range corresponds with one of the peak absorption regions of cytochrome c oxidase (CCO), a key mitochondrial enzyme involved in cellular energy production. In simple terms, this means your cells are particularly good at absorbing red light in this range and using that light to help produce the energy they need to function, repair and recover. 

Unlike a heat lamp or a tanning bed, it uses no UV light. Red-light therapy has been studied for decades, with thousands of published studies exploring how specific wavelengths of light interact with the body. Today, the technology has moved well beyond the research lab and is widely used in professional and at-home devices for applications ranging from skin rejuvenation and healthy aging to muscle recovery, pain relief and overall wellness.

The following information summarizes research available online from peer-reviewed publications on light energy for various health applications. Joylux offers several light-based devices, and each has a different application, FDA regulatory status, and approved claims. vFit® is an FDA-registered Low-Risk General Wellness Device. ILYEO™ body is an FDA-registered Class II, 510(k)-exempt medical device. Please refer to each device's page for its specific application and approved claims.

More Than a Decade of Red‑Light Expertise

Joylux didn't discover red light because it became trendy. We've spent more than a decade developing light-based technologies for women's health, conducting clinical research, engineering medical and wellness devices, and precisely measuring how light is delivered to the body.

That expertise is built into every Joylux red-light device.

More Than Red Light

Joylux devices combine precisely measured red light with gentle heat and vibration, three technologies working together in one treatment. vFit pairs 662 nm red light with warmth that boosts blood flow and natural lubrication, and customizable sonic vibration for comfort. ILYEO body pairs 662 nm red light with soothing heat up to 43°C and gentle vibration that adds comfort to every session.

  • 662 nm red light

    Precisely measured dose

  • Gentle heat

    Built into every session

  • Vibration

    Added comfort

What is red light therapy?

Red-light therapy has been studied for decades, with thousands of published studies exploring how specific wavelengths of light interact with the body. Today, the technology has moved well beyond the research lab and is widely used in professional and at-home devices for applications ranging from skin rejuvenation and healthy aging to muscle recovery, pain relief and overall wellness.

How does red light therapy work?

Think of red light as energy your cells can use.

Specific wavelengths of red light are absorbed by components within your cells, including cytochrome c oxidase in the mitochondria, the structures responsible for producing cellular energy. This interaction can support the production of ATP, the fuel cells use to function, repair and recover.

In simple terms: the right red light helps support your cells in doing what they already do, only more efficiently.

Red light is also believed to support the release of nitric oxide (NO), which supports blood flow and helps nutrients and oxygen travel through the body.¹ Published research on photobiomodulation has explored effects including:

  • Increased circulation
  • Increased collagen and elastin production
  • Reduced inflammation
  • Improved cellular energy and repair
  • Increased antioxidant activity
¹ Chung H, Dai T, Sharma SK, Huang YY, Carroll JD, Hamblin MR. The Nuts and Bolts of Low-Level Laser (Light) Therapy. Annals of Biomedical Engineering, 2012; 40(2):516–533.

What is irradiance in red light therapy?

Irradiance is the strength of light reaching the skin, measured in milliwatts per square centimeter (mW/cm²). It describes how much light power lands on a given area at any moment. Irradiance depends on the LEDs, how many are focused on the area, and how close they sit to the skin. A device held directly against the skin typically delivers more of its light to the target area than one held at a distance.

What does J/cm² mean in red light therapy?

J/cm² (joules per square centimeter) measures the total light energy delivered to an area over a session. It's also called energy density or fluence, and it is the closest thing red light therapy has to a "dose." Fluence equals irradiance multiplied by time. For example, an average irradiance of 47 mW/cm² for 10 minutes delivers approximately 28 J/cm².

Irradiance (mW/cm²)  ×  Time (seconds)  =  Fluence (J/cm²)

How much red light therapy do you need?

The right amount depends on the device and what it's designed for. Session length, how often you use it, and the device's output all work together, so follow the protocol for your specific device. vFit sessions range from 6 to 12 minutes depending on the model and setting. ILYEO body uses one 10-minute session per treatment area. For darker skin tones, start ILYEO body at two minutes and gradually ramp up treatment time.

What determines a red light therapy dose?

A red light therapy dose is the total light energy delivered to an area, measured in J/cm². It depends on the wavelength of the light, how much light the device produces, how concentrated that light is when it reaches the skin, and how long the session lasts. If any one of these is off, the dose changes.

  1. Wavelength (nm)

    The type of light. Joylux devices use red light centered around 662 nm.

  2. Total optical power (mW)

    How much light the device produces overall, measured as total optical power in milliwatts (mW).

  3. Irradiance (mW/cm²)

    How concentrated that power is when it reaches your skin, measured in mW/cm².

  4. Treatment time

    How long each session lasts in minutes.

  5. Total Light Energy/Fluence (J/cm²)

    The dose: how much light energy your skin receives over the entire treatment, measured in J/cm². Too little dose may do nothing, and too much may not mean you get a better result. The right dose is based on clinical evidence.

That's why Joylux devices are engineered to deliver a measured red-light dose, with wavelength, irradiance, and fluence specified by device. You don't just want any red light. You want the right light, delivered with the right power.

Why Some Red-Light Devices Are More Effective Than Others

Seeing red LEDs doesn't necessarily mean you're getting an effective red-light treatment.

What matters is the wavelength, the amount of light actually reaching your body, and the total dose delivered during treatment.

LED count alone tells you very little. A device can contain dozens, or even hundreds, of LEDs and still deliver relatively little energy to the treatment area.

That's why Joylux measures what matters: wavelength, total optical power, irradiance and dose.

How Joylux Uses Red Light Technology

Joylux applies the same 662 nm red-light expertise to two different areas of women's health. vFit is designed for intimate wellness. ILYEO body is designed for targeted relief of minor muscle and joint pain. Each device has its own design, dose, and regulatory status.

  • vFit: Intimate Wellness

    662 nm ± 5 nm red light from 6 high-powered LEDs, paired with gentle warmth and sonic vibration. Delivers up to 17 J/cm² (vFit) or 26 J/cm² (vFit PLUS) per session. Designed to support sensation, natural hydration, and pelvic floor health with consistent use.

    Learn about vFit

  • ILYEO body: Muscle & Joint Relief

    662 nm ± 5 nm red light from 12 high-powered LEDs, delivered directly against the skin with soothing warmth and gentle vibration. 47 mW/cm² average irradiance, delivering approximately 28 J/cm² during a 10-minute treatment.

    Learn about ILYEO body

The Science Behind Our Devices

Spec vFit / vFit PLUS ILYEO body
LEDs 6 high-powered LEDs 12 high-powered LEDs
Wavelength 662 nm ± 5 nm 662 nm ± 5 nm
Average irradiance 43 mW/cm² 47 mW/cm²
Light energy Up to 26 J/cm² in one 12-minute session Up to 28 J/cm² in one 10-minute session
Session 6 to 12 minutes, by model and setting One 10-minute session per treatment area. For darker skin tones, start at two minutes and gradually ramp up.
Safety testing Independently tested to IEC medical electrical and photobiological safety standards: IEC/EN 60601-1; IEC-60601-1; 60601-1-11; IEC/EN-62366--1; IEC/EN-60601-2-83; IEC/EN 60601-1-6; IEC/EN62471:2006; CAN/CSA C22.2 No 60601-2-83

Each device's dose is calibrated for its own application and treatment area.

“Consumers should not have to guess at treatment strength. What matters is the wavelength, measured output, treatment time and placement. Our devices combine measured 662 nm red-light energy, heat and vibration in one targeted treatment.”
 - Dr. Nicolas Loebel, Chief Technology Officer, Joylux

What does research say about red light therapy?

Built on decades of science. Advanced by Joylux.

Thousands of peer-reviewed publications have investigated photobiomodulation and the biological effects of red and near-infrared light. Joylux builds on that scientific foundation, and adds more than a decade of our own product development, clinical research and engineering expertise.

Regulatory status and claims vary by device, so findings in one area don't automatically apply to every product.

Learn More About Red Light Therapy

Frequently Asked Questions

What is photobiomodulation?

Photobiomodulation (PBM) is the scientific name for red light therapy. It describes how certain wavelengths of light interact with cells to support their natural processes.

What does 662 nm red light mean?

"662 nm" refers to red light with a wavelength of about 662 nanometers, a range widely studied in red light research. Joylux devices are centered around 662 nm.

Does red light therapy use UV light?

No. Red light therapy uses visible red light and does not emit UV light.

Does LED count matter in a red light device?

Not on its own. What matters is how much light energy reaches the area you're treating, measured in mW/cm² and J/cm².

How long is a red light therapy session?

It depends on the device. vFit sessions run 6 to 12 minutes, and ILYEO body uses one 10-minute session per treatment area. For darker skin tones, start ILYEO body at two minutes and gradually ramp up treatment time.

Is red light therapy safe to use at home?

At-home devices are designed for home use, and Joylux devices are independently tested to international safety standards. Always follow your device's instructions, and talk with your healthcare provider if you have questions about your health.

Is red light therapy FSA/HSA eligible?

ILYEO body is FSA/HSA eligible.

 Red Light Is Easy. Getting It Right Isn't. 

Anyone can put red LEDs into a device. What matters is delivering the right wavelength, at the right power, for the right amount of time.

Joylux engineers every device around those parameters, so you don't have to calculate wavelengths, watts or joules.

You press a button. We take care of the science.

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NATURAL INTIMATE WELLNESS

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