The science of light

Wavelength.
Tissue interaction.
Clinical application.

Photobiomodulation is one of the most rigorously investigated light-based interventions in contemporary photomedicine. Here is the science behind it.

What is
photobiomodulation?

Photobiomodulation (PBM) is the therapeutic use of specific wavelengths of non-ionising light — typically in the red and near-infrared spectrum — to modulate biological processes at a cellular level. Unlike thermal phototherapies, PBM works through photochemical mechanisms, not heat.

The primary cellular target is cytochrome c oxidase, a terminal enzyme in the mitochondrial respiratory chain. Photon absorption here initiates a cascade of downstream effects: increased ATP synthesis, modulation of reactive oxygen species, altered gene expression and a range of anti-inflammatory responses.

Because the mechanism is photochemical rather than thermal, PBM can be applied safely across skin, subcutaneous tissue, muscle and joint structures — with clinical outcomes that are increasingly documented in peer-reviewed literature.

Key mechanisms

  • Cytochrome c oxidase absorption
  • Increased mitochondrial ATP synthesis
  • Reactive oxygen species modulation
  • Anti-inflammatory cytokine shift
  • Nitric oxide release and vasodilation
  • Enhanced cellular proliferation
  • Modulated pain signalling
How it works

Photon → Cell → Response.

01

Photon delivery

A defined wavelength of light is delivered to tissue at a calibrated irradiance and dose. Wavelength selection determines depth of penetration and the chromophores targeted. Red wavelengths act primarily on superficial tissue; near-infrared reaches deeper structures.

02

Cellular absorption

Photons are absorbed by specific chromophores — primarily cytochrome c oxidase in the mitochondrial inner membrane. This absorption triggers conformational changes in the enzyme and initiates a photochemical cascade independent of thermal effects.

03

Biological response

Downstream effects include increased ATP production, changes in reactive oxygen species, shifts in inflammatory cytokine expression and modulation of cellular signalling. The clinical result depends on tissue type, dose parameters and treatment protocol.

Selective wavelengths used in photobiomodulation
Wavelength reference

Therapeutic
wavelengths.

630 nm

Red — superficial tissue, wound healing, skin

660 nm

Red — dermal penetration, tissue repair, inflammation

810 nm

Near-infrared — muscle, joint, neural tissue

830 nm

Near-infrared — deep tissue, bone, cartilage

1064 nm

Near-infrared — deep penetration, transcranial, dental

Therapeutic effect is wavelength-, dose- and tissue-dependent. Parameter selection should be guided by clinical evidence and professional training. The above is provided as a scientific reference, not a protocol guide.

Dose matters

The Arndt–Schulz
principle.

PBM follows a biphasic dose-response: too little light yields insufficient photon absorption; too much may inhibit the response or produce no additional benefit. Optimal dosing is a function of wavelength, irradiance, exposure time and tissue target — which is why engineering precision matters.

Explore the evidence base
Where it's applied

From principle
to practice.

Photobiomodulation has documented applications across clinical medicine, sports recovery, musculoskeletal rehabilitation, dermatology and human performance. See how we bring this science into professional settings.

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