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Light therapy is clearly enjoying a moment. You can now buy light-emitting tools for everything from complexion problems and aging signs as well as aching tissues and oral inflammation, the latest being a dental hygiene device equipped with small red light diodes, described by its makers as “a significant discovery for domestic dental hygiene.” Worldwide, the industry reached $1 billion in 2024 and is forecast to expand to $1.8 billion by 2035. You can even go and sit in an infrared sauna, where instead of hot coals (real or electric) heating the air, your body is warmed directly by infrared light. As claimed by enthusiasts, it feels similar to a full-body light therapy session, boosting skin collagen, soothing sore muscles, reducing swelling and long-term ailments while protecting against dementia.

Understanding the Evidence

“It appears somewhat mystical,” observes Paul Chazot, a scientist who has studied phototherapy extensively. Of course, certain impacts of light on human physiology are proven. Sunlight enables vitamin D production, essential for skeletal strength, immune function, and muscular health. Light exposure controls our sleep-wake cycles, as well, stimulating neurotransmitter and hormone production during daytime, and preparing the body for rest as darkness falls. Artificial sun lamps are a common remedy for people with seasonal affective disorder (Sad) to combat seasonal emotional slumps. Undoubtedly, light plays a vital role in human health.

Types of Light Therapy

Although mood lamps generally utilize blue-spectrum frequencies, consumer light therapy products mostly feature red and infrared emissions. In rigorous scientific studies, including research on infrared’s impact on neural cells, finding the right frequency is key. Light is a form of electromagnetic radiation, extending from long-wavelength radiation to high-energy gamma radiation. Therapeutic light application uses wavelengths around the middle of this spectrum, including invisible ultraviolet radiation, then visible light (all the colours we see in a rainbow) and then infrared (which we can see with night-vision goggles).

Ultraviolet treatment has been employed by skin specialists for decades to manage persistent skin disorders including eczema and psoriasis. It affects cellular immune responses, “and suppresses swelling,” notes a skin specialist. “Substantial research supports light therapy.” UVA reaches deeper skin layers compared to UVB, while the LEDs in consumer devices (typically emitting red, infrared or blue wavelengths) “generally affect surface layers.”

Safety Considerations and Medical Oversight

The side-effects of UVB exposure, such as burning or tanning, are understood but clinical devices employ restricted wavelength ranges – signifying focused frequency bands – which minimises the risks. “Therapy is overseen by qualified practitioners, so the dosage is monitored,” notes the specialist. Most importantly, the light sources are adjusted by technical experts, “to guarantee appropriate wavelength emission – as opposed to commercial tanning facilities, where regulations may be lax, and wavelength accuracy isn’t verified.”

Commercial Products and Research Limitations

Red and blue LEDs, he notes, “aren’t really used in the medical sense, but could assist with specific concerns.” Red wavelength therapy, proponents claim, enhance blood flow, oxygen absorption and dermal rejuvenation, and stimulate collagen production – a primary objective in youth preservation. “The evidence is there,” comments the expert. “However, it’s limited.” Nevertheless, with numerous products on the market, “it’s unclear if device outputs match study parameters. We don’t know the duration, proper positioning requirements, the risk-benefit ratio. Many uncertainties remain.”

Treatment Areas and Specialist Views

Initial blue-light devices addressed acne bacteria, microorganisms connected to breakouts. The evidence for its efficacy isn’t strong enough for it to be routinely prescribed by doctors – although, notes the dermatologist, “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 advise cautious experimentation and safety verification. Unless it’s a medical device, standards are somewhat unclear.”

Advanced Research and Cellular Mechanisms

At the same time, in a far-flung field of pioneering medical science, Chazot has been experimenting with brain cells, discovering multiple mechanisms for infrared’s cellular benefits. “Virtually all experiments with specific wavelengths showed beneficial and safeguarding effects,” he reports. Multiple claimed advantages have created skepticism toward light treatment – that results appear unrealistic. However, scientific investigation has altered his perspective.

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 created some devices so that we could work with them with cells and with fruit flies,” he says. “I remained doubtful. This particular frequency was around 1070 nanometers, that many assumed was biologically inert.”

Its beneficial characteristic, however, was its efficient water penetration, meaning it could penetrate the body more deeply.

Mitochondrial Effects and Brain Health

More evidence was emerging at the time that infrared light targeted the mitochondria in cells. Mitochondria produce ATP for cell function, generating energy for them to function. “All human cells contain mitochondria, including the brain,” explains the neuroscientist, who concentrated on cerebral applications. “It has been shown that in humans this light therapy increases blood flow into the brain, which is consistently beneficial.”

Using 1070nm wavelength, cellular power plants create limited oxidative molecules. In limited quantities these molecules, says Chazot, “activates protective proteins that safeguard mitochondria, preserve cell function and eliminate damaged proteins.”

Such mechanisms indicate hope for cognitive disorders: free radical neutralization, inflammation reduction, and cellular cleanup – autophagy being the process the cell uses to clear unwanted damaging proteins.

Current Research Status and Professional Opinions

Upon examining current studies on light therapy for dementia, he says, about 400 people were taking part in four studies, incorporating his preliminary American studies