Light is often described as the source of life鈥攁nd in many ways, that鈥檚 true. It drives photosynthesis, regulates our sleep鈥搘ake rhythm, and influences mood. In recent years, though, light has also been promoted as a medical treatment. Some claims make biological sense; others, like so-called intravenous light detox, do not.
As someone who has spent more than two decades studying and applying photobiomodulation (PBM), I鈥檝e seen both credible science and creative marketing. PBM can help, but only when the right wavelengths, doses, and treatment schedules are used.
What photobiomodulation actually is
PBM鈥攆ormerly called low-level laser therapy鈥攗ses low-energy red or near-infrared light, typically between 600 and 1100 nanometers, to influence cellular metabolism. Unlike surgical or cosmetic lasers, it doesn鈥檛 heat or destroy tissue. Instead, light interacts with cytochrome c oxidase, an enzyme in our mitochondria that helps cells produce energy. This interaction releases nitric oxide, increases ATP production, and adjusts oxidative signalling鈥攁ll steps that support repair and reduce inflammation.
In short, PBM is not 鈥渆nergy healing.鈥� It鈥檚 cell biology. But it works only when the dose and exposure are right.
Where the evidence is strongest
Over 6,000 scientific papers and hundreds of clinical trials have examined PBM. The most consistent benefits appear in wound healing - including diabetic ulcers, surgical incisions, and radiation-related skin injuries. PBM speeds tissue repair and calms inflammation by improving blood flow and collagen formation.
Another well-established use is oral mucositis, a painful mouth inflammation caused by cancer treatments. Here, PBM is now part of supportive care in oncology, helping patients eat and recover more comfortably.
There is also reliable evidence that PBM can reduce pain and inflammation in some joint and tendon conditions, such as arthritis and tendinopathies, when applied regularly over several weeks. The World Association for Photobiomodulation Therapy (WALT) provides evidence-based treatment guidelines used worldwide.
Where results are mixed
Not every claim stands up to scrutiny. Cosmetic effects鈥攕uch as smoother skin or fewer wrinkles鈥攁re possible, but only when the light has sufficient power and is delivered uniformly, conditions that most consumer devices on the market have yet to achieve.
Hair-growth helmets may stimulate follicles, yet results vary and depend on consistent use, often alongside other therapies like minoxidil.
Research into PBM for brain and mood health is promising but still early. These ideas need more controlled studies before entering mainstream practice.
For readers interested in the state of evidence, several Cochrane reviews summarize what is known and what remains uncertain.
Why dose matters
One reason PBM results vary so much is that dose matters. Light therapy isn鈥檛 about shining any red light and hoping for the best. The power density and energy delivered per square centimetre must fall within a narrow range. Too little light has no effect; too much can blunt the response.
Deeper tissues need higher intensity and dose than surface skin to deliver enough photons to the target. What truly matters is precise dosing and uniform light coverage鈥攏ot the device鈥檚 cost or whether it employs LEDs or lasers.
What PBM is not
PBM should never be confused with intravenous light therapy or so-called 鈥渂lood irradiation.鈥� Those procedures involve shining light directly into the bloodstream through a catheter and claim to treat everything from Lyme disease to fatigue. They are unsupported and physiologically implausible, and the infection risk outweighs any imagined benefit.
It鈥檚 also different from photodynamic therapy (PDT), which uses light to activate drugs that destroy cancer cells. Both use light, but their mechanisms and goals are completely distinct.
A balanced way forward
When applied correctly, PBM is one of the safest non-drug therapies available. Its side effects are minimal, and its potential continues to expand as studies refine the 鈥渟weet spot鈥� of wavelength and energy. The real challenge is ensuring PBM is used properly and communicated responsibly鈥攚ithout hype, and without dismissing solid science by association with pseudoscience.
Science communication should expose nonsense, yes鈥攂ut also recognize legitimate progress. Light sustains life, and under the right conditions, it can help repair it too.
Dr. Daniel Barolet is a clinician, researcher, and faculty lecturer in the Department of Medicine, Division of Dermatology, at 海角社区. He specializes in light鈥搕issue interactions and photobiomodulation and serves as Director of his Laser Dermatology Clinic and the RoseLab Skin Optics Research Laboratory in Laval, Qu茅bec鈥攂oth affiliated satellite centers of 海角社区.
