Red-light therapy may sound like the new biohacking kid on the block, but it’s older than the hills of ancient Greece.
It’s a modern form of heliotherapy (natural sunlight therapy). The word comes from the Greek helios (sun) and therapeia (treatment).
Long before Hippocrates extolled sunlight’s virtues for health, ancient Egyptians used it for chronic ulcers and skin problems. In India, as early as 1400 BCE, Ayurvedic texts described atapa snana (sunbathing) as a skin remedy.
Across Africa, belief in the sun’s regenerative power is embedded in cultural healing traditions. Globally, sunlight therapy persisted into the 20th century before antibiotics and synthetic drugs took over.
Today, red-light therapy is enjoying a renaissance, powered by rigorous science. It’s now a subset of photobiomodulation (PBM) — the therapeutic use of specific light wavelengths to stimulate biological processes, such as tissue repair, inflammation reduction and pain relief.
PBM includes blue, green and yellow light, though red and near-infrared (NIR) are the most studied and clinically validated. Delivery is via targeted devices using light-emitting diodes (LEDs) to isolate and amplify sunlight’s most regenerative wavelengths.
Medical specialists globally are catching on fast.
Sports physicians prescribe it for muscle recovery and joint pain. Psychiatrists explore its effects on mood and brain function.
Skin specialists are on board, says Cape Town dermatologist Dr Dagmar Whitaker, president of the Melanoma Society SA and vice-president of the World Melanoma Society.
She says about 20% of dermatologists use red LED light (630nm) for nonsurgical treatment of precancerous sunspots (actinic keratosis) and early basal cell carcinomas. They use red light with blue for acne and with brown for wound healing. Whitaker calls it “photodynamic therapy”.
Red-light therapy is also showing promise in treating wrinkles and other signs of ageing.
The most exciting advances by far are in ophthalmology. That’s important since the body’s fastest-ageing organ is the eye. Red light is proving a beacon of hope for chronic vision conditions, including age-related macular degeneration (AMD), for which orthodox medicine offers little to no help.
Other areas of advance include neurology and endocrinology.
A world leader in the research is Prof Glen Jeffery, neurobiologist at University College London’s (UCL) ophthalmic centre.
Jeffery says the biggest research obstacle is “starvation of red light” in modern living and the digital age. He says it’s “a serious public health concern”.
A major factor is widespread use of general-purpose LED bulbs in homes, offices and screens, with little or no red or infrared light.
“These bulbs are designed for brightness and energy efficiency, not cellular stimulation,” Jeffery says.
Most are heavy on blue wavelengths that disrupt circadian rhythms and impair mitochondrial function. Even “warm-white” or “cosy” LEDs mostly lack deep red wavelengths needed for optimal mitochondrial stimulation.
The combination of excessive blue and insufficient red light exacts a high price on health.
“The consequences go far beyond declining vision,” says Jeffery.
His research focuses on mitochondria, which he calls the body’s “battery”. Like all batteries, mitochondria eventually lose their charge.
Jeffery’s research shows the power of deep red (650nm-700nm) and NIR (780nm-2500nm) light to “recharge” mitochondria. That’s helpful, since “in almost every disease, mitochondria will play some role even if secondary”, he says.
Mitochondria are microscopic structures in most human cells. They generate energy by converting nutrients into adenosine triphosphate (ATP), which scientists call the body’s “universal energy currency”.
ATP powers most vital bodily process. Some body parts need more ATP energy than others, depending on mitochondrial density.
The retina is one. It’s the most mitochondria-dense region, with photoreceptor cells (rods and cones) that need vast energy to process light and maintain visual signalling.
Its macula, a small patch at the back of the retina, is even more energy demanding. It has the highest mitochondrial density in the retina, and likely in all human tissues.
Jeffery isn’t claiming red-light therapy cures AMD. His research shows that it can slow the condition and sometimes improve vision. He stresses early intervention and potential for reclaiming retinal function.
“Many retinal cells slip into a dormant state before dying. That’s when we need to catch them,” Jeffery says.
That dynamic applies to any chronic, degenerative condition caused by impaired mitochondrial function.
However, the real light revolution in health lies not in expensive gadgets but in basic environmental changes, says Jeffery. “Simply changing your kitchen lights and home lighting to bulbs closer to natural sunlight can help.”
He recommends incandescent or halogen bulbs with richer red-light components.
Jeffery has architects and designers in his sights. He urges them to be mindful when choosing interior lighting and window glass.
He is scathing about the new building for the internationally renowned Moorfields Eye Hospital under construction near his UCL lab. It will use glass that blocks infrared light to save energy and LED lights “that are cheap with a lot of blue in them”.
“I’ve spoken repeatedly to those responsible, but no-one is listening yet,” he says.
Beyond eye health, Jeffery’s research shows that red light can improve metabolic conditions, such as blood-sugar control. In a recent study, a single 15-minute exposure to 670nm red light reduced glucose spikes after meals by 27.7%.
In the US, Nasa research showed that astronauts exposed to conventional LED lighting 24/7 for months on the International Space Station had symptoms of premature ageing and prediabetes. Scientists attribute this to mitochondrial changes.
“This points to the crucial role of natural light balance in human health and longevity,” Jeffery says.
In the US, Dr Andy Rosenfarb brings red-light therapy into sharp clinical practice. Rosenfarb, a New Jersey-based doctor of naturopathy and traditional Chinese medicine (TCM), is also a licensed acupuncturist.
He has practised “integrative ophthalmology” for more than 20 years. He developed ophthalmic electro-acupuncture protocols used in research with Johns Hopkins University and Nova Southeastern University.
For the past five years, Rosenfarb has integrated red-light therapy into holistic protocols for degenerative eye diseases, including AMD, retinitis pigmentosa, glaucoma and diabetic retinopathy.
Protocols include red-light eyeglasses, which he developed for home use for a few minutes daily. In clinic and online consultations, Rosenfarb notes promising results showing improvements in lost vision.
In the UK in 2020, business person Stephen Allen extended his Planet Lighting company to develop red-light eyeglasses based on Jeffery’s research. In 2022, within six months of launch, Allen’s self-funded, spin-off Eyepower company sold more than 2,500 units globally.
Jeffery and his lab have no commercial interest in Eyepower.
Looking ahead, Jeffery, Rosenfarb and Whitaker envision red-light therapy as an accessible, noninvasive intervention for diverse health issues.
Jeffery encourages people with AMD to “go out in sunlight with its natural balance of blue and red between seven and 11 in the morning”.
He is cautiously optimistic about the growing popularity of infrared saunas. “It’s worth keeping an eye on,” he says. However, he defers judgment as he has “no real idea what the energy levels are and exactly what wavelengths [these saunas] use”.
Jeffery cautions against commercial misuse of “red-light therapy” devices as a panacea for ageing: “Few, if any, of these companies have the technology to test their devices. At best, some are ineffective and potentially harmful.”
Whitaker says professional devices are incomparable to home devices: “They have a much higher energy output and therefore need strict monitoring.”
Once devices go beyond strict medical use, it’s difficult to control reproducibility, she says. This leads to variable results and disappointment. It may just be from incorrect use, “like buying a car but never going for a driving lesson”.
Rosenfarb says biology “has not caught up to technology, specifically the quantity of blue-light radiation exposure”.
Blue-light protection from screens is critical, as cases of macular degeneration are showing up two decades earlier than before, he says. Putting screens on night mode, less screen time, eyedrops containing NAC (N-acetylcysteine) and carotenoid antioxidants can help.
Red-light therapy may not be a panacea for all ills. But evolving science is illuminating the power of light itself, and red light as a natural ally in combating mitochondrial wear and tear.
From mitochondria to macula, mobility and mood, red-light therapy is reshaping how we think about light, not just as illumination but as powerful medicine.
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