There is a version of the red-light conversation that is all promise and no mechanism. This is not that. What follows is the actual biology — what the light does when it reaches a cell, which wavelengths do it, and where the published evidence is strong versus where it is still thin.
Your cells have a light receptor. Most people have never heard of it.
Inside almost every cell in your body sit mitochondria — the structures that convert oxygen and food into ATP, the molecule that powers everything you do. At the end of the mitochondrial electron transport chain is an enzyme called cytochrome c oxidase.
Cytochrome c oxidase absorbs light. Not metaphorically — measurably. Its absorption spectrum has substantial peaks in the red and near-infrared range, roughly 600 to 850 nanometres. This is the foundation of the entire field, and it is not controversial.
Professor Michael Hamblin, for two decades a principal investigator at the Wellman Center for Photomedicine at Massachusetts General Hospital and a faculty member at Harvard Medical School, has published more on this mechanism than almost anyone alive. In his 2018 review in Photochemistry and Photobiology, he sets out the leading explanation: nitric oxide, which under stress binds to cytochrome c oxidase and throttles it, can be dissociated by red and near-infrared photons. Remove the brake, and electron transport resumes. Mitochondrial membrane potential rises. ATP production increases.
The primary site of light absorption in mammalian cells has been identified as the mitochondria, and more specifically cytochrome c oxidase.
Hamblin's more recent work, including a 2022 paper with Ann Liebert, argues the picture is broader still — that light-gated ion channels and redox signalling are also involved, and that cytochrome c oxidase is not the whole story. That is what a healthy field looks like: the mechanism is being refined, not abandoned.
Why the dose matters more than the marketing
Here is the part most brands leave out. Photobiomodulation follows a biphasic dose response. Too little light does nothing. Too much can do less than nothing. The relationship between dose and benefit is a curve, not a ladder — and this is precisely why irradiance, session length and distance are specifications worth reading rather than numbers to skim past.
It is also why Hamblin's reviews repeatedly note that PBM can have apparently opposite effects depending on whether a cell is healthy or stressed. Light is a signal, not a nutrient. Signals can be under-delivered and over-delivered.
The eye study that made the mechanism impossible to dismiss
If you want a single experiment that demonstrates this is real biology rather than wishful thinking, look at the work of Professor Glen Jeffery at the UCL Institute of Ophthalmology.
The retina is the most metabolically demanding tissue in the human body, and it ages early — mitochondrial function in retinal cells begins measurably declining from around age 40. Jeffery's team tested whether 670nm light could shift that.
Published in Scientific Reports in 2021, the finding was striking: a single three-minute exposure to deep red light improved colour contrast sensitivity in participants aged 37 to 70 — and the improvement persisted for a week. In younger participants, it did nothing at all, which is exactly what the mitochondrial-decline hypothesis predicts.
That last detail is the one to sit with. A placebo effect does not politely skip the under-40s. An effect that appears only in the population with measurable mitochondrial ageing is an effect that behaves like a mechanism.
Five wavelengths, because tissue is not uniform
Different wavelengths reach different depths. Red light in the 600–660nm range is absorbed at and near the skin's surface. Near-infrared from roughly 800–950nm passes considerably deeper, reaching muscle, joint and connective tissue.
This is why single-wavelength devices are a compromise. A 660nm panel is working on your skin. An 850nm panel is working on tissue beneath it. Neither is wrong; each is partial.
Every BioHackX Labs bed fires the full clinical spectrum in a single session:
- 633nm — surface absorption; skin tone, texture, complexion
- 660nm — reaches the dermis; local circulation and collagen
- 810nm — near-infrared, penetrates into muscle
- 850nm — joints and deeper tissue; the workhorse for whole-body recovery
- 940nm — the deepest-penetrating wavelength in the range
The Apex Bed delivers this across 41,600 medical-grade LEDs at 129 mW/cm², with independent control of each wavelength and pulse frequency from 0 to 10,000 Hz. Those numbers exist because dose is the mechanism, and the mechanism is the point.
What we are not claiming
Photobiomodulation is one of the better-evidenced areas in the wellness category, and it is still a field with real gaps. Study protocols vary enormously in wavelength, dose and delivery, which makes pooled analysis difficult and means some outcomes rest on lower-certainty evidence than others. Anyone telling you the science is settled across every application is overselling.
Our beds are wellness tools, not medical devices. They are not intended to diagnose, treat, cure or prevent any disease. If you have a specific health condition, talk to your doctor before starting.
What we will say is this: the absorption spectrum is measured, the mechanism is published, and the effect shows up in populations where the biology predicts it should. That is a more honest foundation than most things you can buy.
References
- Hamblin MR. Mechanisms and Mitochondrial Redox Signaling in Photobiomodulation. Photochemistry and Photobiology, 2018. PubMed 29164625
- Hamblin MR, Liebert A. Photobiomodulation Therapy Mechanisms Beyond Cytochrome c Oxidase. Photobiomodulation, Photomedicine and Laser Surgery, 2022. Read
- Shinhmar H, Grewal M, Sivaprasad S, et al. (Jeffery G, senior author). Optically improved mitochondrial function redeems aged human visual decline. / Weeklong improved colour contrast sensitivity after single 670 nm exposures. Scientific Reports, 2021. Nature Scientific Reports
- UCL News. Morning exposure to deep red light improves declining eyesight. 2021. UCL
Neither Professor Hamblin, Professor Jeffery, UCL nor Massachusetts General Hospital has any affiliation with BioHackX Labs, and none has endorsed our products. We cite their published research because it is the evidence base for the technology, not because they are associated with us.