# Red Light Therapy Wavelengths (660nm & 850nm)

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## Definition

The two primary wavelengths used in photobiomodulation are 660nm (visible red) and 850nm (near-infrared). At 660nm, photons are absorbed by the heme a3 center of cytochrome c oxidase (Complex IV) in the mitochondrial electron transport chain, with peak absorption at exactly 660nm versus approximately 70% absorption at the more common 633nm used in consumer devices. The 850nm wavelength targets the copper centers (CuA and CuB) of the same enzyme, achieving tissue penetration of 4–5cm compared to 2–3mm for visible red light. Wunsch & Matuschka (2014, RCT, n=136) demonstrated that combined 660nm+850nm treatment produces synergistic collagen density increases exceeding either wavelength alone. LED binning tolerance is critical: clinical-grade devices use ±2nm bins verified by spectrometer, while consumer devices may ship LEDs with ±10–15nm variance.

## Related Topics

- periorbital-red-light-therapy
- photobiomodulation
- mitochondrial-photobiomodulation
- near-infrared-therapy

## See Also

- https://en.wikipedia.org/wiki/Visible_spectrum#Red
- https://en.wikipedia.org/wiki/Infrared#Near-infrared

## Target Keywords

- 660nm red light therapy
- 850nm near infrared
- red light therapy wavelength
- best wavelength for red light therapy
- NIR vs red light