IN THIS LESSON: MECHANISMS OF ACTION

Health Professional Version

The principal chromophore for NIR light in neural tissue is cytochrome c oxidase (CCO), the terminal enzyme of the mitochondrial respiratory chain. Photon absorption dissociates inhibitory nitric oxide (NO) from CCO, increasing mitochondrial membrane potential, oxygen consumption, and ATP synthesis. Laser-mediated NO release also relaxes vascular and lymphatic endothelium, increasing cerebral blood flow and activating the brain waste removal system via meningeal lymphatic vessels. Preclinical laser studies further demonstrate anti-inflammatory microglial polarization from M1 to M2 phenotypes, reduced oxidative stress, and upregulation of brain-derived neurotrophic factor (BDNF), supporting neurogenesis and synaptic plasticity.

Layperson Version

Near-infrared (NIR) light works in the brain mainly by stimulating a key enzyme inside your cells’ “power plants” (mitochondria) called cytochrome c oxidase.

In simple terms:

  • The light helps remove a natural “brake” (nitric oxide) from this enzyme, allowing cells to produce more energy (ATP).

  • This boosts overall cell activity and efficiency.

It also affects blood flow and fluid movement:

  • It relaxes blood vessels, which improves circulation in the brain.

  • It helps activate the brain’s waste-clearing system (similar to a drainage system), which may aid in removing toxins.

On a cellular and immune level:

  • It shifts brain immune cells into a more healing, anti-inflammatory state.

  • It reduces harmful oxidative stress (cellular “wear and tear”).

  • It increases levels of BDNF, a protein that supports the growth of new brain cells and strengthens connections between them.

You can think of NIR light like tuning up an engine—it helps brain cells make more energy, improves fuel delivery (blood flow), clears out waste, and supports repair and regeneration.

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