Blue light-emitting diodes in hair regrowth: the first prospective study

What the authors concluded

An increase in hair density and hair shaft width was recorded in 90% of patients after 10 weeks. Photographic improvement was noted in 80% of the patients." " The only side effect consisted in a darkening of the hair, perhaps due to melanic stimulation due to blue light in 2 patients.

Devices that emit this wavelength

Matched on wavelength within 15nm, since LED bins vary by roughly that much and a tighter match would be false precision. Where we have an irradiance figure, the session length is the time needed to reach this study's dose of 120 J/cm² at that intensity.

Matching a wavelength is not the same as reproducing a trial. Session times assume the device's published irradiance is accurate at the distance it was measured, which on brand-claim figures is often optimistic. Where a device publishes both a peak and an average we use the average, and where it publishes a falloff curve we use the lowest figure, so these times run long rather than short. Clinical protocols also control for spot size, contact and skin type in ways a home device cannot.