Step into the Light
Photobiomodulation (Red & NIR light therapy)
Step into the light
Introduction
The light bulb was invented in the late 19th century, it was possible to provide light locally to different parts of the body. The vision of laser light in the 1960s made it possible to centralize single-wavelength light and use it for therapeutic applications (LLLT; low-level laser therapy). The new LED light technology has made it possible to replace the soft laser with the most economical LEDs with sufficient luminous efficacy that can narrow the wavelength of light precisely enough.
The link between light and human health has inspired the research in different types of light therapy. Especially within recent years, lightweight devices that emit different wavelengths (colors) of light have been developed. These include red & near-infrared light (NIR) devices that have been noticed to support skin health, wound healing, tissue repair, and even contribute to neural health. This post lists the ways red light & NIR might improve various aspects of health. There are currently over 5000 published research articles on the effect of red light therapy on these effects.
The effects of low-level laser therapy (LLLT) and photobiomodulation are characterized by inverted U-shaped dose-response curves, in which linear responses may be seen only at shallow doses. Whereas linear effects may be negligible, maximal stimulatory effects are typically observed at intermediate doses. However, the linear relationship does not hold at high doses since inhibitory effects are observed instead.
Image: Hormetic effect of photobiomodulation (LLLT; low-level laser therapy).
How does photobiomodulation works?
Red light therapy uses light energy, a form of electromagnetic radiation (EMR). Human cells contain molecules whose functioning can be altered when receiving EMR. Indeed, the uptake of EMR is a necessary process that enables life on Earth. For example, the eye contains photoreceptors that absorb light and contribute to the vision. In addition, some cells contain molecules that are not related to the concept per se but have particular molecules that accept light waves (these are called photoreceptors). In these cells, the light waves cause biological chain reactions that contribute to energy production in the cell.
Photobiomodulation utilizes non-ionizing photonic energy to trigger photochemical changes within cellular structures that are receptive to photons, particularly in mitochondria. Red light and NIR light therapy are believed to mainly work through photo acceptors – the most critical photo acceptor being an enzyme called cytochrome c oxidase.
Red light therapy uses exclusively red- to near-infrared light waves (λ = 600–1100 nm). Red light waves penetrate through the skin and make their way to the cell's mitochondria, increasing the cells' energy production. For example, various events lead to the acceleration of mitochondrial respiration via cytochrome c oxidase. Red light also supports