How Red Light Therapy Works
Four variables decide whether a device does anything at all. Wavelength, irradiance, distance, time. Everything else is packaging.
The short version
Red and near-infrared light occupy a narrow band of the spectrum — roughly 600 to 900 nanometres — that passes into skin more readily than other visible wavelengths. Researchers call the field photobiomodulation: how cells respond to specific wavelengths delivered at specific doses.
The most-discussed mechanism involves cytochrome c oxidase, an enzyme in the mitochondria that absorbs light in this range. The working hypothesis is that this absorption influences cellular energy production and signalling. It is an active area of research, not a settled one.
Two wavelengths, two depths
Most quality devices use both, because most of what you would point a device at is not a single depth.
The four variables that actually matter
Change any one of these and you change the dose. A device with perfect wavelengths, used at the wrong distance, delivers very little.
Wavelength
Determines how deep the light lands. Surface, or further in.
Irradiance
How much energy reaches a given area, in mW/cm². The honest spec.
Distance
Doubling the gap cuts delivered energy sharply. Follow your manual.
Time
More is not better. There is a window, and you can overshoot it.
Longer sessions are not better sessions
The photobiomodulation literature repeatedly describes a biphasic dose response: a window where the dose appears useful, above and below which the effect drops away. Doubling your session time can move you past that window rather than deeper into it. Short and regular beats long and occasional.
Being straight with you
PHŌRMA devices are wellness products. They are not medical devices, they do not diagnose or treat any condition, and nothing on this page is medical advice. Published results in this field vary considerably, and so does study quality — anyone promising guaranteed outcomes is overselling.
If you are pregnant, have a photosensitive condition, take photosensitising medication, have an eye condition, or are dealing with a genuine injury — speak to a doctor before adding light to the picture.