The mice didn't cooperate. Or, more accurately, they cooperated in the most irritatingly useful way: a low-powered laser that failed at its original job seemed to make shaved lab animals regrow hair and heal wounds faster. That accidental clue helped launch photobiomodulation, which is science-speak for "maybe certain kinds of light can nudge cells," and also the reason your social feed now looks like a nightclub for cheekbones.

The Glow-Up With a Footnote

Red light therapy sounds like something invented by a spa with a fog machine and a very confident influencer. But under the marketing confetti sits a real idea: red and near-infrared wavelengths can pass into tissue without burning it, and cells may respond. The recent Nature piece by Shamini Bundell and Maren Hunsberger gets right to the awkward bit: glowing masks, helmets, vests, and fiber-optic needles are everywhere, while researchers are still sorting out which claims are biology and which are deluxe lamp enthusiasm (Bundell and Hunsberger, 2026).

In dermatology, photobiomodulation usually means red light around 620-700 nanometers or near-infrared light above that range, delivered by LEDs or lasers to trigger non-heating biological effects (Maghfour et al., 2024; Mineroff et al., 2024). Simple? Adorable thought. Biology heard "simple" and brought 17 cousins, a fog machine, and a mitochondrial enzyme.

The Mitochondria May Be Squinting Back

The lead suspect is cytochrome c oxidase, also called Complex IV, an enzyme in mitochondria. If mitochondria are your cells' battery packs, cytochrome c oxidase is one of the workers passing electrons down the line while muttering, "Please stop calling everything biohacking." It helps cells use oxygen to make ATP, the energy currency your body spends on repair, signaling, and remembering why you opened the fridge.

The hypothesis is that red or near-infrared photons affect cellular molecules, including cytochrome c oxidase, which can shift mitochondrial activity, nitric oxide signaling, inflammation, blood flow, and oxidative stress. That is the tidy version. The messy version: wavelength matters, dose matters, timing matters, tissue depth matters, device design matters, and skin and skull are not transparent sandwich bags.

That last part matters for brain claims. Transcranial photobiomodulation asks light to travel through scalp and skull to influence brain tissue. Bold commute. Reviews of neurodegenerative-disease PBM describe plausible mechanisms and early signals, but also small studies, inconsistent protocols, and the giant practical question of how much light reaches the target (Salehpour et al., 2024).

Not All Red Lights Are Playing the Same Game

The best human evidence is not one big glowing blob. Dermatology and wound-related uses have stronger footing than many wellness claims. A 2025 evidence-based consensus in the Journal of the American Academy of Dermatology concluded that PBM is safe for adults and identified evidence-supported uses including peripheral neuropathy, androgenic alopecia, wound ulcers, diabetic-foot-ulcer pain, decubitus ulcers, and acute radiation dermatitis (Maghfour et al., 2025).

That does not mean every red panel on the internet can fix your knees, tune your brain, reverse aging, and make your ex regret everything. Pub quiz answer: "FDA-cleared" is not the same as "proven for every claim on the box." It often means the device passed a regulatory pathway for a specific use or resembles an existing device. Useful information, yes. Magic wand, no.

For cognition, the evidence is intriguing but still wearing training wheels. A 2026 randomized, double-blind pilot trial in EClinicalMedicine tested home-based intranasal and transcranial PBM for post-COVID "brain fog" in 43 adults. It found the treatment feasible and safe, with hints of cognitive benefit, especially in younger participants, but the primary result did not clear the usual statistical finish line. Translation: suspicious footprint, not Colonel Mustard in the conservatory (Lim et al., 2026).

The Sensible Answer Is Annoying

If reproducible, PBM could be genuinely useful: noninvasive, relatively low risk, and potentially helpful for problems involving inflammation, tissue repair, pain, or cellular energy stress. Chronic wounds, neuropathy, radiation dermatitis, and brain fog are not tiny inconveniences. They are quality-of-life thieves wearing lab coats.

But light is not a pill with a tidy dose. It scatters, reflects, fades, and behaves differently across tissues. Too little may do nothing; too much may cancel the effect. Photobiomodulation has a Goldilocks problem, except Goldilocks is a mitochondrion and the porridge has wavelength settings.

So the sane position is neither "red light cures everything" nor "this is all nonsense." Some applications look promising. Some are overmarketed into orbit. The next round belongs to larger trials, clearer dosing, independent testing, and fewer claims that sound like they were written by a blender full of hashtags.

References

1. Bundell S, Hunsberger M. Red light therapy: the science behind the hype. Nature. 2026. https://doi.org/10.1038/d41586-026-01643-0
2. Maghfour J, Ozog DM, Mineroff J, Jagdeo J, Kohli I, Lim HW. Photobiomodulation CME part I: Overview and mechanism of action. Journal of the American Academy of Dermatology. 2024;91(5):793-802. https://doi.org/10.1016/j.jaad.2023.10.073
3. Mineroff J, Maghfour J, Ozog DD, Lim HW, Kohli I, Jagdeo J. Photobiomodulation CME part II: Clinical applications in dermatology. Journal of the American Academy of Dermatology. 2024;91(5):805-815. https://doi.org/10.1016/j.jaad.2023.10.074
4. Maghfour J, Mineroff J, Ozog DM, et al. Evidence-based consensus on the clinical application of photobiomodulation. Journal of the American Academy of Dermatology. 2025;93(2):429-443. https://doi.org/10.1016/j.jaad.2025.04.031
5. Lim L, Hosseinkhah N, Van Buskirk M, et al. Photobiomodulation for cognitive dysfunction (Brain Fog) in post-COVID-19 condition: a randomized double-blind sham-controlled pilot trial. EClinicalMedicine. 2026;92:103730. PubMed

Disclaimer: The image accompanying this article is for illustrative purposes only and does not depict actual experimental results, data, or biological mechanisms.