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Light-based treatment is clearly enjoying a moment. Consumers can purchase illuminated devices designed to address skin conditions and wrinkles to sore muscles and periodontal issues, the latest being an oral care tool outfitted with tiny red LEDs, promoted by the creators as “a significant discovery in at-home oral care.” Worldwide, the market was worth $1bn in 2024 and is projected to grow to $1.8bn by 2035. You can even go and sit in an infrared sauna, where instead of hot coals (real or electric) heating the air, the thermal energy targets your tissues immediately. As claimed by enthusiasts, it’s like bathing in one of those LED-lit beauty masks, enhancing collagen production, easing muscle tension, relieving inflammation and persistent medical issues and potentially guarding against cognitive decline.

The Science and Skepticism

“It sounds a bit like witchcraft,” notes a Durham University professor, professor in neuroscience at Durham University and a convert to the value of light therapy. Naturally, we know light influences biological functions. Our bodies produce vitamin D through sun exposure, crucial for strong bones, immune defense, and tissue repair. Sunlight regulates our circadian rhythms, as well, triggering the release of neurochemicals and hormones while we are awake, and preparing the body for rest as darkness falls. Daylight-simulating devices are standard treatment for winter mood disorders to boost low mood in winter. So there’s no doubt we need light energy to function well.

Different Light Modalities

While Sad lamps tend to use a mixture of light frequencies from the blue end of the spectrum, consumer light therapy products mostly feature red and infrared emissions. In serious clinical research, such as Chazot’s investigations into the effects of infrared on brain cells, finding the right frequency is key. Light constitutes electromagnetic energy, extending from long-wavelength radiation to high-energy gamma radiation. Phototherapy, or light therapy uses wavelengths around the middle of this spectrum, the highest energy of those being invisible ultraviolet, followed by visible light encompassing rainbow colors and infrared light visible through night vision technology.

UV light has been used by medical dermatologists for many years to treat chronic skin conditions such as eczema, psoriasis and vitiligo. It modulates intracellular immune mechanisms, “and suppresses swelling,” notes a skin specialist. “Considerable data validates phototherapy.” UVA goes deeper into the skin than UVB, while the LEDs in consumer devices (usually producing colored light emissions) “typically have shallower penetration.”

Safety Protocols and Medical Guidance

UVB radiation effects, like erythema or pigmentation, are understood but clinical devices employ restricted wavelength ranges – meaning smaller wavelengths – that reduces potential hazards. “Treatment is monitored by medical staff, thus exposure is controlled,” explains the dermatologist. Essentially, the lightbulbs are calibrated by medical technicians, “to ensure that the wavelength that’s being delivered is fit for purpose – unlike in tanning salons, where oversight might be limited, and we don’t really know what wavelengths are being used.”

Consumer Devices and Evidence Gaps

Colored light diodes, he explains, “aren’t really used in the medical sense, though they might benefit some issues.” Red light devices, some suggest, help boost blood circulation, oxygen absorption and dermal rejuvenation, and promote collagen synthesis – an important goal for anti-aging. “Studies are available,” comments the expert. “But it’s not conclusive.” Regardless, given the plethora of available tools, “it’s unclear if device outputs match study parameters. Appropriate exposure periods aren’t established, how close the lights should be to the skin, the risk-benefit ratio. Numerous concerns persist.”

Targeted Uses and Expert Opinions

One of the earliest blue-light products targeted Cutibacterium acnes, a microbe associated with acne. Scientific backing remains inadequate for regular prescription – although, explains the specialist, “it’s frequently employed in beauty centers.” Some of his patients use it as part of their routine, he says, though when purchasing home devices, “we just tell them to try it carefully and to make sure it has been assessed for safety. Without proper medical classification, the regulation is a bit grey.”

Advanced Research and Cellular Mechanisms

Simultaneously, in advanced research areas, scientists have been studying cerebral tissue, revealing various pathways for light-enhanced cell function. “Pretty much everything I did with the light at that particular wavelength was positive and protective,” he states. Multiple claimed advantages have created skepticism toward light treatment – that claims seem exaggerated. Yet, experimental evidence has transformed his viewpoint.

The researcher primarily focuses on pharmaceutical solutions for brain disorders, however two decades past, a GP who was developing an antiviral light treatment for cold sores sought his expertise as a biologist. “He developed equipment for cellular and insect experiments,” he says. “I was pretty sceptical. It was an unusual wavelength of about 1070 nanometres, which most thought had no biological effect.”

What it did have going for it, however, was its ability to transmit through aqueous environments, allowing substantial bodily penetration.

Mitochondrial Effects and Brain Health

Additional research indicated infrared affected cellular mitochondria. Mitochondria produce ATP for cell function, generating energy for them to function. “All human cells contain mitochondria, even within brain tissue,” says Chazot, who, as a neuroscientist, decided to focus the research on brain cells. “Studies demonstrate enhanced cerebral circulation with light treatment, which is generally advantageous.”

With 1070 treatment, cellular power plants create limited oxidative molecules. In limited quantities these molecules, explains the expert, “activates protective proteins that safeguard mitochondria, protect cellular integrity and manage defective proteins.”

These processes show potential for neurological conditions: free radical neutralization, anti-inflammatory, and cellular cleanup – autophagy representing cellular waste disposal.

Ongoing Study Progress and Specialist Evaluations

Upon examining current studies on light therapy for dementia, he reports, about 400 people were taking part in four studies, comprising his early research projects