George Dagerotip/Unsplash
Better sleep, boosted mood, fewer wrinkles 鈥 these are just a handful of the supposed benefits of red light, delivered onto your skin via laser or light-emitting diodes (LEDs). Indeed, if the wellness industry is to be believed, simply bathing in a rosy glow for a few minutes a day can cure a whole host of ailments, from hair loss and acne to chronic pain and depression, and that is just scratching the surface.
Given the hype, you听would be forgiven for thinking this is just an expensive fad. After all, if something sounds too good to be true, it听probably is.
While evidence for most of these claims is thin at best,听there is听another world听of听red-light therapy that is far more exciting听than the prospect of a glow-up.听Emerging听evidence finds it may mitigate cognitive decline, and researchers are now trialling the technology for conditions such as Alzheimer鈥檚 and Parkinson鈥檚, with many more applications in the pipeline.听鈥淚t’s slowly starting to get traction,鈥 says听 at the University of Grenoble Alpes in France, who has been working on red-light therapy for 15 years. 鈥淲hen I started, there might have been 10 or 20 publications a year,听but now there听are听thousands.鈥澨听
Lighten up
Using electromagnetic radiation is commonplace in medicine. Doctors routinely deploy X-rays to peer at bones and ultraviolet light to ease certain skin conditions. Yet unlike these, red light falls within the visible spectrum, the narrow band of wavelengths detectable by the human eye. Its wavelengths are longer than other visible lights, like blue or green light, spanning between around 650 and 750 nanometres. This allows it to pass through the dead outer layer of our skin, penetrating a few millimetres beneath. The longer the wavelength, the deeper it travels.
Once consigned to dermatologist offices and spas, red-light therapy is now readily available via consumer devices such as face masks and full-body panels. Influencers peddle it on social media, and the US Food and Drug Administration has cleared devices for acne and hair loss, though they听aren鈥檛听yet approved as clinically effective.
Yet research on red-light therapy goes back to 1960, with the invention of the laser. Biomedical researchers quickly wondered whether these narrow beams of light had medical applications. They soon got their answer.
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In 1967, the听physicist听Endre Mester at Semmelweis University in Budapest, Hungary,听shone听red听lasers听with a wavelength of听694 nanometres听onto shaved mice听to see听if it听triggered听skin cancer. It听didn鈥檛听鈥 instead,听it听.
Mester later discovered the lasers enhanced wound healing and started using them to treat ulcers and other intractable wounds in people. A new branch of medicine, which Mester called low-level laser therapy (LLLT), was born. Other scientists discovered the light doesn鈥檛 have to be visible: near-infrared with wavelengths between 700 and 850 nanometres, just beyond the visible spectrum, also had healing effects. LEDs could also be used instead of lasers.
The science behind听LLLT 鈥撎齨ow rebranded as听photobiomodulation听鈥撎齣sn鈥檛听fully understood,听but we have the basics, says听听at University College London. When red or near-infrared light strikes the skin, it听acts on听specialised structures听in underlying cells听called mitochondria. It is here 鈥 the power packs of cells 鈥 that the light does its scintillating work.
Mitochondria听contain听light-absorbing molecules called chromophores. One,听cytochrome听c听oxidase, is especially important.听It is a key听component听in听the pathway听that听cells use to produce听the听energy-carrying molecule听ATP. Absorbing red or听near-infrared听light stimulates cytochrome听c听oxidase,听speeding up the process听and producing more ATP.
This is beneficial for听several听reasons. As we get older,听mitochondria鈥檚 efficiency听dwindles, and with it,听their听ability to produce sufficient energy. 鈥淏y the time you reach middle age, you’ve generally got an ATP deficit,鈥澨齭ays Jeffery.
This has another downside: the overproduction of reactive oxygen species 鈥 volatile chemicals that wreak havoc on nearby cells, spurring inflammation. 鈥淏y the time you鈥檙e 30, you鈥檝e got systemic inflammation, and systemic inflammation is one of those things that’s going to kill you in the end,鈥 says Jeffery. It contributes to all manner of chronic illnesses, including diabetes, heart disease and cancer.
Red light speeds up the process by which cells produce energy Bakhrom Tursunov/Alamy
Stimulating mitochondria with red light makes up the ATP deficit and dials down听reactive oxygen species听鈥 in other words,听it听rejuvenates.听It听,听such as prostaglandins.听鈥淯nquestionably ATP goes up,鈥 says Jeffery. 鈥淯nquestionably inflammation goes down.鈥澨齀t鈥檚听win, win.
The process听also听appears to boost听a mechanism by which cells heal one another,听called the biophoton effect.听Cells produce light, particularly in their mitochondria, and use it to communicate with听each听other.听鈥淐ells in distress issue听ultraviolet听or blue light. But if听it’s听happy and healthy,听it’ll听be red and听near-infrared,鈥 says听Mitrofanis. 鈥淭hey use this light to repair each other. If a cell is dying,听it communicates this,听and then nearby cells give it red and near-infrared light.鈥
Exogenous light听can听profoundly affect听energy metabolism. In 2024,听Jeffery and his colleague听 at City St George鈥檚, University of London, shone red light onto a small area of the upper backs of 15 people without underlying health conditions. The participants then drank sugary water and underwent periodic blood-sugar testing over the next 2 hours. On average, blood sugar was nearly听听in this group听than听in听a separate group of 15 people听who听hadn鈥檛听received听red light,听indicating听the light had stimulated their mitochondria, helping them听to听more efficiently听convert sugar听into ATP.
The research also suggests that the effects spread beyond the light-soaked mitochondria, as the small patch of skin cannot account for the large impact, says Jeffery. This may be related to the mysterious abscopal effect, a rare phenomenon in cancer radiotherapy where irradiation of a primary tumour can shrink secondary tumours located elsewhere, he says.
Healing at home?
Consumer companies touting red-light therapy for wellness have seized on this scientific explanation. In the early 2000s, plastic surgeons began using it to aid post-operative wound healing, and word spread of its healing powers. Clinics started offering it to people who hadn鈥檛 undergone surgery, and the first at-home devices soon followed.
Red-light therapy is now a booming business. According to fashion magazine听, the global market was worth around $520 million in 2021 and is forecast to reach $800 million by 2031. Salons, spas and gyms increasingly offer it alongside massages and facials. Consumers can buy at-home devices, ranging from hand-held wands and face masks to helmets and blankets, the cheapest of which cost around 拢100 ($135), but some go for thousands.
Companies market the products as an easy route to wellness and cosmetic improvement. The list of concerns they are purported to help with includes, but is not limited to, wrinkles, hair loss, acne, stretch marks, inflammation, pain, insomnia, obesity, athletic performance, erectile dysfunction, menstrual cramps, depression, brain fog, infertility and age-related deterioration.
Given the general rejuvenating and energy-burning effects of red light, these claims seem plausible. But in fact, most of them are 鈥渉ighly dubious鈥, says Jeffery. However, there are some bright spots.
In 2025,听a team led by dermatologist听听at Duke University in North Carolina reviewed听59 studies听鈥撎齟ncompassing听more than 1880 people听鈥撎齩n听using听, from actinic cheilitis to acne. When it came to cosmetic use, 鈥渢he strongest evidence is for acne, including with some home-use LED devices鈥, says Pavlis.
Pavlis found the therapy听can be听as good as, or sometimes better than,听standard听acne听drug treatments. For instance,听one study听showed听12 weeks of red-light therapy听, on average. In comparison, an oral antibiotic paired with topical adapalene 鈥 a standard acne treatment 鈥 led to just a 69 per cent reduction. Acne-specific devices often emit blue and red light, as both wavelengths can kill off pimple-causing bacteria.
The review also found the treatment evened out skin tone in people with psoriasis 鈥 an autoimmune condition 鈥 or rosacea, where skin becomes ruddy and bumpy. Both use cases, however, have been tested in only a single clinical trial.
What of wrinkles and general skin rejuvenation? Here the evidence is mixed. In听,听60 per cent of participants听saw听fewer听wrinkles听and an improvement in overall skin tone, as evaluated by a dermatologist. But听听found no听.
Some studies suggest that red-light therapy may prevent and even reverse hair loss Martin Parr/Magnum Photos
Hair growth is another area with promise. At any one moment, around 15 per cent of hair follicles are dormant, which precedes hair falling out. The vigorous fur regrowth Mester observed in his shaved mice was probably from hair follicles getting a red-light energy boost, jolting those that would have been resting into action.
The same appears听true in听humans.听In a听, researchers in South Korea used a helmet to beam red light onto the scalps of 30 adults with androgenetic alopecia, the most common form of hair loss. Participants used the device every other day for 25 minutes, while a separate group of 29 people did so with a mock version. After 16 weeks, hair density in those who got the real deal increased more than 57 per cent, on average, compared with the control group. Their hair strands also thickened, whereas those in the control group thinned. But it isn鈥檛 known how long this effect lasts.
Mester鈥檚 other application, wound healing, also听has some backing.听 have found red and near-infrared light can help heal burns, scars and diabetic foot ulcers. However, most of them included just a handful of participants, meaning the evidence isn鈥檛 definitive. Which wavelength works best also isn鈥檛 known, though some research points towards the 630-to-660-nanometre range.
Studies have听even听shown听that听the therapy may听, especially when combined with diet and exercise. Yet almost all of them had fewer than 100 participants. And claims that red-light therapy can remove fat from specific areas 鈥 known as 鈥渟pot fat鈥 reduction 鈥 are questionable. In 2016, researchers at Nicolaus Copernicus University in Poland illuminated one side of 24 people鈥檚 bellies with a consumer red-light device, leaving the other side untouched. After six sessions, there was .
As for the rest of the purported benefits, forget it. The evidence simply doesn鈥檛 exist.
So, does that mean that at-home red light therapies have got the, er, green light? Not necessarily. Even in cases where evidence backs red light, devices vary in how they deliver it, using different wavelengths for different durations, and research hasn鈥檛 settled on which combo is best.
More importantly, consumer devices are, on the whole, too powerful, says Jeffery, emitting an order of magnitude more power than the few milliwatts needed to nudge mitochondria. Consumer devices typically deliver 60 milliwatts per square centimetre. But the optimal power is around a tenth of that 鈥 and Jeffery has seen effects at less than 1 milliwatt per square centimetre.
Face masks have become a popular way of delivering red-light therapy Juli Konia/Alamy
鈥淭he [wellness] industry just loves the concept of more and more power,鈥 says Jeffery. And, in the case of red light, more isn鈥檛 better. Turbocharging cellular energy production can gum up the whole system, with potentially serious consequences, including a build-up of those havoc-wreaking reactive oxygen species, he says.
Such an influx might explain why red-light therapy seems to lessen wrinkles. Because these molecules cause inflammation, they may temporarily plump up skin. Jeffery worries that people who use powerful red-light devices regularly are storing up trouble. 鈥淲e don’t know what’s going to happen in 10 years鈥 time,鈥 he says. 鈥淢aybe your face is going to drop off.鈥
When it comes to buying your own red-light device, Jeffery鈥檚 advice is: don鈥檛 bother. 鈥淵ou鈥檙e doing more harm than good, and you鈥檙e wasting money.”
Beyond aesthetics
The hype around these potential cosmetic uses has outshone the ways red-light therapy is advancing into mainstream medicine.
More than 200 clinical trials听have tested the tech for听treating听15 illnesses. A听 found it showed promise for 12 of them, with the strongest evidence for fibromyalgia, osteoarthritis and cognitive impairment.
Fibromyalgia听is a poorly听understood听condition characterised by听, leading to insomnia, fatigue and depression. It has few treatments. Yet the review found red-light therapy can help alleviate its symptoms, including the primary one, pain. It also reduces pain and disability in knee osteoarthritis and, to a lesser degree, improves burning mouth syndrome, neck pain, diabetic foot ulcers and some kinds of tendinopathy. But for six conditions 鈥 rheumatoid arthritis, plantar fasciitis, Achilles tendinopathy, fractures, carpal tunnel syndrome and tinnitus 鈥 there is no effect.
Perhaps most surprisingly, it may slow age-related cognitive impairment. A 2023 review of 11 clinical trials, mostly involving people with Alzheimer鈥檚 and Parkinson鈥檚, but also some with traumatic brain injuries, found transcranial near-infrared light most promising. With this in-clinic treatment, light passes through the skull, into outer brain regions. 鈥淲e鈥檙e talking 20 to 30 millimetres, and that’s certainly enough to get to our best piece of brain,鈥 says Mitrofanis, referring to the cerebral cortex, which carries out functions such as planning and short-term memory. Red-light therapy can鈥檛 cure or even halt cognitive decline, but it could听, probably through boosting energy production in struggling brain cells.
While positive, the evidence remains uneven, with studies ranging from single sessions up to 72, each lasting between 30 seconds and 30 minutes. This underscores the need for larger, more standardised trials, some of which are already under way.
Mitrofanis and his colleagues are trialling an optical fibre that delivers near-infrared light deep into brain regions affected by Parkinson鈥檚 disease. He is also investigating its treatment potential for traumatic brain injury, stroke, Lewy body dementia and depression, and preliminary results are encouraging. 鈥淭he patients felt better, their get-up-and-go was better, they had less fatigue, their mood was better,鈥 he says. 鈥淏ut there is a long way to go.鈥 The technology must still undergo multiple clinical trials, and researchers must pinpoint the best delivery method for each condition.
If that pans out, in the long term, the sky may be the limit. 鈥淭his thing will potentially help any cell that’s in distress as long as it’s not too far in distress,鈥 says Mitrofanis. 鈥淚f mitochondria are too damaged, nothing will save [them]. But if you’ve got early signs of distress 鈥 the mitochondria are starting to get a bit wobbly 鈥 then you can save it.鈥
In other words, red-light therapy might help any condition in which cells are struggling 鈥 which is many of them. It may not be too long before we are all basking in a red glow, not because of social media hype, but because it is doctor鈥檚 orders.
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