5 min read · Launch edition
660 nm and 850 nm, explained without the hype
Two numbers appear on almost every red light product sold. They are not grades or quality tiers — they describe where in the spectrum the light sits.
What a nanometre figure describes
A wavelength in nanometres describes the position of light in the electromagnetic spectrum. Visible red sits roughly between 620 and 700 nm. Near-infrared begins past about 780 nm and is largely invisible, which is why a panel running near-infrared alone can look almost switched off.
A higher number is not a better number. It is a different part of the spectrum with different absorption behaviour in tissue.
Why both bands appear together
Published photobiomodulation research spans both the red and near-infrared ranges, and absorption behaviour differs between them — red is absorbed nearer the surface, near-infrared passes further before it is absorbed.
Manufacturers combine the two so one device covers both. It is a coverage decision, not evidence that combining them produces any particular result.
Dose is intensity multiplied by time
The figure that actually describes an exposure is dose, expressed in joules per square centimetre. Dose is irradiance multiplied by the number of seconds you are exposed.
That means a lower-intensity device held closer for longer and a higher-intensity device further away for less time can deliver a comparable dose. It also means an irradiance figure quoted without a distance tells you nothing you can act on.
More is not automatically better
Photobiomodulation research frequently describes a biphasic dose response, where increasing the dose past a certain point does not continue to increase the observed effect. This is a finding about the literature, not a promise about any device.
Practically: long sessions are not obviously superior to short ones, and consistency is the variable most people are actually short of.
Go deeper
The Red Light Dosing Guide
The practical companion to this article: how to set distance and duration together, and how to tell a measured irradiance figure from a marketing one.
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Skyluxe devices are general wellbeing products. They are not intended to diagnose, treat, cure or prevent any disease. Information on this site is general in nature and is not medical advice. Consult a qualified health practitioner before starting any new routine, particularly if you have a medical condition, are pregnant, or take photosensitising medication.