What is red light therapy and how does it work?

What happens during red light therapy?

During red light therapy, a device with LEDs shines red light — and sometimes near-infrared light — onto the skin. Part of this light is absorbed by the skin, which starts biological processes. This response to light is called photobiomodulation.[1][2]

Curious what photobiomodulation can mean for your skin? Read the skin article.

What is the difference between LED, red light and near-infrared?

• LED stands for Light Emitting Diode. This is the technology inside the device that produces the light.
• Red light is visible light. It has shorter wavelengths than near-infrared light.
• Near-infrared light is almost invisible light. It has longer wavelengths than red light and can therefore usually penetrate the skin more deeply.[3]

Many devices combine red light and near-infrared light, because both types of light may contribute to visible skin improvement.[1][2]

What do wavelengths mean?

A wavelength indicates the type of light that the LED emits. nm stands for nanometre, the unit of measurement for the length of a light wave.

On red light devices you therefore often see numbers such as 633 nm, 660 nm, 830 nm or 850 nm.

• Wavelengths around 630 to 660 nm belong to red light.[3]
• Wavelengths around 830 to 850 nm belong to near-infrared light.[3]

Different devices can use one or more wavelengths. The nm figures indicate which light types a device emits.

This basic article helps you understand the terms in product information and technical specifications more easily.