Your LED Device May Be Causing PIH—Here's Why Dark Skin Is at Risk

Описание: Here are the referenced articles that back up all the information provided in this video. I’ve broken it down into sections so you can see the points clearly.

SECTION 1 — Melanin as a “Light Sink”

“Melanin absorbs light and reduces the number of photons reaching deeper layers.”

Reference:

Optical Absorption of Melanin - by Steven Jacques

https://omlc.org/spectra/melanin/

Visible-light reviews confirm that melanin is the dominant absorber in the epidermis and determines how deeply light penetrates.

Reference:

The Emerging Role of Visible Light in Melanocyte Biology and Skin Pigmentary Disorders: Friend or Foe?

https://www.mdpi.com/2077-0383/12/23/...

SECTION 2 — Wavelength Differences

Blue Light (415 nm)


“Blue light is strongly absorbed by melanin and penetrates the least.”

Melanin’s absorption is highest at shorter wavelengths.
Visible light induces stronger pigmentation in darker skin photo-types.

Red Light (630–660 nm)

“Red light penetrates deeper and is less affected by melanin.”

Red wavelengths experience lower melanin absorption and therefore penetrate more deeply into the dermis.
-Visible‑light reviews confirm that different wavelengths interact differently with melanin and skin photo-types.

Near‑infrared (810–850 nm) is least affected by melanin

Melanin absorption is “almost completely attenuated” above 700 nm, meaning NIR passes through the epidermis with minimal melanin interference.
NIR is the most consistent and predictable wavelength across darker skin tones.

References:

Same as section one and -

https://www.cl.cam.ac.uk/~jgd1000/mel...

Photochemistry and Photobiology, 2021, 97: 911–91
Role of Visible Light on Skin Melanocytes: A Systematic Review
Aparna Chauhan and Norbert Gretz*
Medical faculty of Mannheim, Medical Research Center, University of Heidelberg, Mannheim, Germany
Received 26 November 2020, accepted 10 May 2021, DOI: 10.1111/php.13454

https://onlinelibrary.wiley.com/doi/p...

SECTION 3 — Heat Diffusion

“Melanin absorbs light and heat, so darker skin may feel warmth sooner.”

Melanin is a major absorber that converts light into heat.

Reference:

Optical Absorption of Melanin - by Steven Jacques

https://omlc.org/spectra/melanin/

SECTION 4 — Biological Response Differences

“Darker skin has different baseline structures and may respond differently to LED.”

Visible‑light pigmentation responses differ significantly by phototype.
Melanin density alters how light is absorbed and how cells respond.

Reference:

Photochemistry and Photobiology, 2021, 97: 911–91
Role of Visible Light on Skin Melanocytes: A Systematic Review
Aparna Chauhan and Norbert Gretz*
Medical faculty of Mannheim, Medical Research Center, University of Heidelberg, Mannheim, Germany
Received 26 November 2020, accepted 10 May 2021, DOI: 10.1111/php.13454

https://onlinelibrary.wiley.com/doi/p...

SECTION 5 — Hyperpigmentation, PIH, Melasma


“Visible light can worsen pigmentation in darker skin; red/NIR are safer.”


Visible light induces pigmentation, especially in darker skin photo-types.
Blue‑violet wavelengths are particularly implicated in pigmentation responses.

Reference:

Same as above.

SECTION 6 — Safe LED Use

“Darker skin is more prone to PIH, so avoid irritation and start slow.”


Visible‑light pigmentation responses are stronger in darker skin.
Melanin absorbs more energy → more heat → more risk of irritation.

Reference:

Same as above.