Red Light Therapy Technical Guide

Red Light Therapy Technical Guide

For those who want to look beyond just 660nm, 850nm, or the number of LEDs. This technical guide clearly explains the key parameters of red light therapy.

1. Wavelength

Wavelength is expressed in nanometers (nm). Many consumer devices use red light around 630–660nm and/or near-infrared light around 830–850nm. Wavelength is important but does not solely determine the outcome.

2. Irradiance: mW/cm²

Irradiance describes how much optical power arrives per unit area. A value can only be properly interpreted when the measurement distance and method are also clear.

3. Dose: J/cm²

Dose describes the total energy per unit area. In a simplified model: dose (J/cm²) = irradiance (W/cm²) × time (seconds).

Example

50 mW/cm² = 0.05 W/cm². At 600 seconds, the theoretical dose is 30 J/cm².

4. Why more wattage isn't automatically better

Wattage is electrical power and not the same as irradiance on the skin. A larger or more powerful device is therefore not automatically the best choice.

5. Why LED count is limited

The number of LEDs means little without information about wavelength, optical output, distribution, distance, and treatment time.

6. Distance and positioning

Light exposure can change when the distance to a source changes. Therefore, follow the recommended distance for the specific device and do not use stated irradiance values independently of their measurement conditions.

7. How to compare two devices?

First, compare the purpose and treatment area.
Check the wavelengths.
Check irradiance and measurement distance when available.
Review treatment time and recommended frequency.
Assess treatment surface, comfort, and ease of use.
Check safety information and manual.

8. What you can't infer from a single number

No single number — not LED count, wattage, nm, or a claimed dose — proves that a device is better. The protocol and total light exposure should be considered together.

9. Science versus consumer product

Research into photobiomodulation (PBM) uses specific devices, parameters, and protocols. A research result should therefore not automatically be translated to every consumer device.