Every term you need to read light like a clinician — from wavelength and dose to mitochondria and melatonin, defined in plain language and grounded in the science behind our devices.
A graph showing how strongly a biological response changes with wavelength. It tells you which colours of light a given effect actually “listens” to — for example, the cell’s energy machinery responds most around the red and near-infrared bands.
The molecule cells use to store and spend energy — often called the body’s energy currency. Red and near-infrared light is studied for its ability to support how mitochondria produce ATP.
The principle that there is a sweet spot for light. Too little does little, an optimal dose helps most, and far too much can flatten or reverse the benefit — so with light therapy, more is not always better.
The roughly 24-hour internal clock that governs sleep, alertness, hormones and metabolism. Light is its strongest signal: bright light by day and dimmer, warmer light by evening help keep the rhythm aligned.
A property of laser light in which the waves march in perfect step. For most cell-level light effects the wavelength and dose matter far more than whether the source is coherent, which is why well-designed LEDs can do the job of lasers.
The main structural protein that gives skin its firmness, bounce and smoothness. Red light around 660 nm is studied for supporting the fibroblasts that build collagen, which is why it is associated with skin tone and texture.
A hormone that naturally peaks in the morning to help you wake and wind down toward night. Morning light exposure is linked to a healthy cortisol curve and steadier daytime energy.
An enzyme in the mitochondria thought to be the main “antenna” that absorbs red and near-infrared light. Its sensitivity peaks in the red (~620 and ~680 nm) and near-infrared (~760 and ~825 nm) bands — the core of why those wavelengths are used.
The total energy delivered to an area, measured in joules per square centimetre. Dose = irradiance (mW/cm²) × time (s) ÷ 1000; it is the number biology actually responds to, not the minutes on the clock.
The low-level electromagnetic emission produced by a device’s electronics and power supply. Premium light devices are engineered to keep EMF low at the distances you actually sit, for comfortable everyday use.
The skin cell responsible for producing collagen and elastin. Stimulating fibroblast activity is one of the proposed routes by which red light supports skin firmness and repair.
Rapid, often invisible fluctuation in a light’s brightness caused by its driver electronics. High flicker can feel fatiguing, so quality panels are designed for low or flicker-free output.
Another word for light dose — the energy delivered per unit area, in J/cm². “Fluence” and “dose” are used interchangeably when describing how much light a session delivers.
Light made of many coordinated wavelengths rather than one. Where a single diode sends one signal, a spectrum spanning ultraviolet, violet, visible red and near-infrared more closely mirrors the layered light of natural sunlight. The distinction matters: almost every panel emits only red and near-infrared — reproducing the sun's ultraviolet and violet bands is what sets a true full spectrum apart.
The idea that a small, well-judged stress makes a system stronger. The biphasic response of light therapy is a form of hormesis: a sensible dose prompts a beneficial adaptation, while excess does not.
How much light power lands on a given area, measured in milliwatts per square centimetre (mW/cm²). Higher irradiance reaches a target dose faster — but it must always be quoted at a stated treatment distance to mean anything.
Two ways to deliver therapeutic light. Lasers are coherent and tightly focused; LEDs spread broad, even light over large areas. For whole-body and skin use, LED panels deliver comparable wavelengths and dose far more practically and safely.
A small semiconductor that emits light at a specific wavelength. Modern LEDs let a single device combine many precise wavelengths into one even, full-spectrum field.
A light-sensing pigment in special cells of the eye that reports daylight to the brain’s master clock. It is most sensitive to blue light around 480 nm, which is why blue light by day energises and blue light at night disrupts sleep.
The hormone that signals night and prepares the body for sleep. Its release is suppressed by blue light — the effect peaks near 464 nm — so warm, low-blue evening light helps protect it.
The tiny power plants inside almost every cell, where energy (ATP) is made. They are the main target of red and near-infrared light therapy, and the reason it is studied across skin, recovery and vitality.
A billionth of a metre, the unit used to measure wavelength. Visible red light sits around 630–700 nm and near-infrared above 700 nm — small differences in nanometres point light at different tissues.
Invisible light just beyond red, roughly 700–1400 nm. Because it penetrates more deeply than visible red, NIR (e.g. 810 nm) is associated with muscle, joint and deeper-tissue support.
A signalling molecule that helps relax blood vessels and support circulation. Red and near-infrared light is thought to release nitric oxide from the mitochondria, helping restore normal energy flow. Sunlight has a second route red + near-infrared-only devices miss: UVA (around 365 nm) mobilises a separate store of nitric oxide in the skin, associated with vasodilation and lower blood pressure.
The “therapeutic window” of roughly 600–1300 nm where light passes most readily through skin and tissue. Red and near-infrared sit inside it, which is why those bands are favoured for reaching cells beneath the surface.
How far light travels into tissue before being absorbed. It increases from red toward near-infrared, so 660 nm acts mainly at the skin while 810 nm reaches deeper structures.
The scientific name for red and near-infrared light therapy: using specific wavelengths of light to gently influence how cells work. “Photo” (light) + “biomodulation” (adjusting biology).
A single particle of light. Light therapy is, at heart, the delivery of photons of the right wavelength to cells that can absorb and respond to them.
A molecule or cell that absorbs light and turns it into a biological signal. Cytochrome c oxidase in mitochondria and melanopsin in the eye are two photoreceptors central to how the body reads light.
Switching the light rapidly on and off rather than running it continuously. Pulsed delivery is studied as a way to shape the dose and the cellular response, and features in some advanced devices.
Visible light roughly 630–700 nm. Absorbed mostly at and just under the skin, red light around 660 nm is most associated with skin tone, collagen and surface recovery.
How far you sit from the light source. Because irradiance falls off steeply with distance — close to an inverse-square law — the same panel delivers a very different dose at 15 cm versus 45 cm, so distance is part of the dose.
The longer band of ultraviolet light in sunlight (~315–400 nm; ~365 nm in our system). UVA is associated with mobilising nitric oxide in the skin — linked to wider blood vessels and circulation. Like UVB, it is absent from red + near-infrared-only devices; reproducing it, at brief and measured doses, is part of what a true full spectrum restores. Never enough to tan or burn.
The shorter, higher-energy band of ultraviolet in sunlight (~280–315 nm; the ~297 nm line is most active). UVB is what prompts the skin to make its own vitamin D — something red and near-infrared light cannot do. It is the band almost every panel skips, so only a true full-spectrum device reproduces it, in brief, controlled doses, never enough to burn.
A hormone-like nutrient the body makes when UVB light (around 297 nm) strikes the skin. It supports bone, immune and whole-body health. Crucially, red and near-infrared light cannot make vitamin D — only UVB can — which is why a full-spectrum device that includes a UVB band, rather than red + NIR alone, is what reproduces this part of the sun.
The distance between two peaks of a light wave, measured in nanometres, which determines its colour and how deep it travels. Choosing wavelengths — not just brightness — is what makes a light device effective.
Educational reference, not medical advice. These definitions describe general principles from the light-and-wellness literature; individual responses vary. Nothing here is intended to diagnose, treat or cure any condition — consult a qualified professional about your health.
REDelios ONE puts ten wavelengths, three circadian modes and a true full spectrum into a single panel — the vocabulary above, made physical.