The Science · Topic
How light works
Every article we’ve written on this topic, newest first, with the research behind it and the limits stated plainly.
The library
Everything we’ve written, sorted by what you want to know.
Seven topics, from the basics of how light works to research that is still early. Pick a topic, or search for the thing you’re curious about.
How light works
The fundamentals: wavelengths, depth, dose, and what happens inside a cell when light arrives.
The Science of the Stack
Why Combining 415nm Blue and 660nm Red Light is EssentialModern skincare is moving away from "single-focus" solutions. Just as a complete regimen requires both cleansing and protection, effective light therapy relies…
The Ultimate Guide to Photobiomodulation
How Red and Blue Light Therapy Actually Transform Your Skin, Hair, and BodyIntroduction: Beyond the Glow If you’ve spent any time researching modern wellness, you’ve likely asked: "Does red light therapy work?" It’s a…
Red Light Therapy for Inflammation
How Light Helps Calm Your Body, Backed by ScienceEmerging research suggests that red light therapy (photobiomodulation) may help reduce inflammation by influencing cellular energy production, balancing inflammatory signals, and supporting…
Red Light Therapy vs Infrared Therapy for Anti-Aging
What Works Best for Your Skin?Introduction Aging skin is a universal concern: from fine lines and sagging to loss of glow and firmness. But with the rise…Nothing on that yet.
Try a broader word: “skin”, “hair”, “recovery” or “wavelength”.Myth or fact
Six things people say about red light. Call it, then flip.
Tap Myth or Fact on each card. Every answer comes with the science, and a link if you want the long version.
0/6
called right-
Myth or fact?
Red light therapy is basically UV light.
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Myth or fact?
Longer sessions give better results.
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Myth or fact?
Blue and red light do different jobs.
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Myth or fact?
You’ll see a difference within a week.
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Myth or fact?
You can use red light alongside retinol.
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Myth or fact?
A bigger irradiance number always means a better device.
Glossary
Speak fluent light.
The words that unlock every article in the library. Start at the top: each one builds on the last.
01 / 14Glossary
The scientific name for red light therapy: specific wavelengths of red and near-infrared light used to influence how cells behave, without heating or damaging the skin.
It’s the word the research uses. Search for it and you’ll be reading studies, not marketing.
02 / 14Glossary
The distance between the peaks of a light wave, measured in nanometres. It sets the colour you see, and how far light travels into skin.
Blue 415 → Green 520–560 → Red 630–660 → Near-infrared 830–850 nm
Different wavelengths do different jobs, and longer wavelengths generally travel deeper.
03 / 14Glossary
Light just beyond what the eye can see, from about 700 nm. Light-therapy devices typically use 810–850 nm.
It reaches deepest of the wavelengths in most devices, and because it’s invisible, a near-infrared LED can look dim or even off while it’s working.
04 / 14Glossary
How much light power lands on each square centimetre of skin, measured in milliwatts per square centimetre. It always depends on distance.
A number quoted without a distance means very little, and a bigger number isn’t automatically better.
05 / 14Glossary
The total light energy delivered in a session: irradiance multiplied by time. Researchers also call it fluence.
30 mW/cm² × 900 seconds = 27 J/cm²
It’s why sessions are timed. Twice the time means twice the dose, which isn’t always better.
06 / 14Glossary
Too little light does nothing, the right amount helps, and too much can cancel the benefit out. The curve rises, peaks and falls.
Too little → the effective window → too much
It’s why an Aeterna mask session is timed at fifteen minutes, on purpose.
07 / 14Glossary
Structures inside almost every cell that turn food and oxygen into usable energy. They are the best-studied target of red and near-infrared light.
Helping mitochondria work more efficiently is the leading explanation for why light affects skin, hair and muscle at all.
08 / 14Glossary
An enzyme inside the mitochondria, thought to be where photobiomodulation begins: it absorbs red and near-infrared light.
Its absorption bands sit in the red and near-infrared, part of why device wavelengths aren’t arbitrary.
09 / 14Glossary
The molecule cells spend as energy. Light-stimulated mitochondria are thought to make more of it.
More available energy is thought to help cells with their everyday work: repairing, renewing and building.
10 / 14Glossary
A signalling molecule that relaxes blood vessels. Light is thought to release it from cytochrome c oxidase, where it can slow energy production.
Freed nitric oxide may improve local circulation, one reason light is studied for recovery.
11 / 14Glossary
The cells in the dermis that build collagen and elastin: skin’s scaffolding.
Most skin-focused light research is really about these cells.
12 / 14Glossary
The protein that gives skin its structure and firmness. We make less of it with age, and sun exposure breaks it down faster.
Red light is studied for its effect on collagen, with changes measured over months, not days.
13 / 14Glossary
Light-sensitive molecules made by the bacteria involved in acne (C. acnes). They absorb blue light strongly at around 415 nm.
When they absorb blue light they produce reactive oxygen that is harmful to the bacteria, the basis of blue-light acne care.
14 / 14Glossary
The growth phase of a hair follicle. At any moment, most hairs on a healthy scalp are in anagen.
Light therapy for hair is studied for helping follicles enter and stay in this phase, which is why results take months.
Fifteen minutes of the light you’ve just read about.
The Aeterna mask brings red, blue, green and near-infrared light to every plane of the face and neck: FDA 510(k) cleared, wireless, and timed at fifteen minutes.
Meet the mask