The Science
Everything we’ve written on red light and skin: what it does, what it doesn’t, and what the research actually says. Sorted by topic, searchable, and written for the curious.
The light explorer
Wavelength decides everything: the colour you see, and how far light travels into skin. Slide from blue to near-infrared, or tap a stop.
415 nm
520–560 nm
630–660 nm
830–850 nm
Illustrative, not to scale. Real depth varies with skin type, thickness and device; the layers shown are simplified from published optical studies of human skin.
The library
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.
The fundamentals: wavelengths, depth, dose, and what happens inside a cell when light arrives.
Lines, firmness, breakouts, tone and calm: the reason Aeterna exists, and the best-studied use of red light.
How red and near-infrared light are studied for thinning hair, and why hair results take months, not weeks.
Joints, muscles, back pain and inflammation: where near-infrared’s extra depth matters most.
Routines, seasons, skincare pairings and longevity: how light fits into an ordinary week.
Irradiance claims, price tags and form factors: how to read a spec sheet without being sold to.
Early, promising and unproven: where scientists are looking next. Interesting reading, not a treatment claim.
These articles summarise early research. Aeterna devices are not intended to diagnose, treat, cure or prevent any disease, including the conditions discussed here. Please speak with your doctor about any medical condition.
Nothing on that yet.
Try a broader word: “skin”, “hair”, “recovery” or “wavelength”.Myth or fact
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 rightRed light therapy is basically UV light.
Longer sessions give better results.
Blue and red light do different jobs.
You’ll see a difference within a week.
You can use red light alongside retinol.
A bigger irradiance number always means a better device.
Glossary
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.
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