How Does Red Light Therapy Work? The Cellular Energy Mechanism, Explained

Most red light therapy questions start with "does it work," but the more interesting question is often "how would it even work?" A 2020 review in Photobiomodulation, Photomedicine, and Laser Surgery lays out the leading scientific explanation.

What the research looked at

This narrative review examined decades of research into the cellular mechanism behind photobiomodulation, focusing on cytochrome c oxidase (CCO) — the final enzyme in the mitochondrial electron transport chain, responsible for producing ATP, the molecule cells use as energy currency.

What they found

The proposed mechanism: red and near-infrared light is absorbed by CCO and photodissociates inhibitory nitric oxide bound to one of its active sites, which can restore the enzyme's activity. In studies where this has been observed, it's associated with increased mitochondrial membrane potential, higher oxygen consumption, and greater ATP output — in short, cells producing more usable energy. Importantly, the review itself notes this mechanism remains debated, flagging reproducibility concerns in some prior studies.

What this means in practice

This is the most scientifically contested piece of the red light therapy picture — a plausible, well-studied proposed mechanism rather than a settled fact. It's worth understanding as context for why red and near-infrared wavelengths specifically are used in therapy devices, rather than treating it as proof of any particular health outcome on its own.