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Light therapy is certainly having a moment. Consumers can purchase light-emitting tools for everything from dermatological concerns and fine lines as well as sore muscles and gum disease, recently introduced is a dental hygiene device outfitted with small red light diodes, marketed by the company as “a major advance for domestic dental hygiene.” Worldwide, the industry reached $1 billion in 2024 and is forecast to expand to $1.8 billion by 2035. There are even infrared saunas available, where instead of hot coals (real or electric) heating the air, the thermal energy targets your tissues immediately. According to its devotees, the experience resembles using an LED facial mask, boosting skin collagen, easing muscle tension, alleviating inflammatory responses and long-term ailments while protecting against dementia.

Research and Reservations

“It appears somewhat mystical,” notes a neuroscience expert, professor in neuroscience at Durham University and a convert to the value of light therapy. Certainly, certain impacts of light on human physiology are proven. Sunlight helps us make vitamin D, crucial for strong bones, immune defense, and tissue repair. Sunlight regulates our circadian rhythms, additionally, stimulating neurotransmitter and hormone production during daytime, and winding down bodily functions for sleep as it fades into night. Artificial sun lamps are standard treatment for winter mood disorders to elevate spirits during colder months. Undoubtedly, light plays a vital role in human health.

Various Phototherapy Approaches

Although mood lamps generally utilize blue-spectrum frequencies, most other light therapy devices deploy red or infrared light. In serious clinical research, such as Chazot’s investigations into the effects of infrared on brain cells, finding the right frequency is key. Photons represent electromagnetic waves, which runs the spectrum from the lowest-energy, longest wavelengths (radio waves) to the highest-energy (gamma waves). Light-based treatment uses wavelengths around the middle of this spectrum, with ultraviolet representing the higher energy invisible light, then visible light (all the colours we see in a rainbow) and infrared light visible through night vision technology.

Ultraviolet treatment has been employed by skin specialists for decades for addressing long-term dermatological issues like vitiligo. It affects cellular immune responses, “and reduces inflammatory processes,” explains Dr Bernard Ho. “There’s lots of evidence for phototherapy.” UVA reaches deeper skin layers compared to UVB, in contrast to LEDs in commercial products (which generally deliver red, infrared or blue light) “tend to be a bit more superficial.”

Risk Assessment and Professional Supervision

Potential UVB consequences, including sunburn or skin darkening, are understood but clinical devices employ restricted wavelength ranges – indicating limited wavelength spectrum – which minimises the risks. “Treatment is monitored by medical staff, thus exposure is controlled,” notes the specialist. And crucially, the light sources are adjusted by technical experts, “to guarantee appropriate wavelength emission – unlike in tanning salons, where oversight might be limited, and wavelength accuracy isn’t verified.”

Consumer Devices and Evidence Gaps

Colored light diodes, he says, “don’t have strong medical applications, but could assist with specific concerns.” Red wavelength therapy, proponents claim, improve circulatory function, oxygen absorption and dermal rejuvenation, and activate collagen formation – a primary objective in youth preservation. “The evidence is there,” states the dermatologist. “But it’s not conclusive.” Nevertheless, with numerous products on the market, “we don’t know whether or not the lights emitted are reflective of the research that has been done. Appropriate exposure periods aren’t established, how close the lights should be to the skin, the risk-benefit ratio. Many uncertainties remain.”

Treatment Areas and Specialist Views

One of the earliest blue-light products targeted Cutibacterium acnes, microorganisms connected to breakouts. Scientific backing remains inadequate for regular prescription – although, explains the specialist, “it’s often seen in medical spas or aesthetics practices.” Some of his patients use it as part of their routine, he mentions, but if they’re buying a device for home use, “we advise cautious experimentation and safety verification. Without proper medical classification, the regulation is a bit grey.”

Advanced Research and Cellular Mechanisms

Meanwhile, in a far-flung field of pioneering medical science, 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 says. It is partly these many and varied positive effects on cellular health that have driven skepticism about light therapy – that results appear unrealistic. Yet, experimental evidence has transformed his viewpoint.

The researcher primarily focuses on pharmaceutical solutions for brain disorders, but over 20 years ago, a physician creating light-based cold sore therapy requested his biological knowledge. “He designed tools for biological testing,” he recalls. “I remained doubtful. This particular frequency was around 1070 nanometers, that many assumed was biologically inert.”

The advantage it possessed, however, was its efficient water penetration, enabling deeper tissue penetration.

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, producing fuel for biological processes. “Mitochondria exist throughout the body, including the brain,” explains the neuroscientist, who concentrated on cerebral applications. “Research confirms improved brain blood flow with phototherapy, which is generally advantageous.”

With specific frequency application, mitochondria also produce a small amount of a molecule known as reactive oxygen species. In limited quantities these molecules, notes the scientist, “triggers guardian proteins that maintain organelle health, look after your cells and also deal with the unwanted proteins.”

All of these mechanisms appear promising for treating a brain disease: antioxidant, anti-inflammatory, and pro-autophagy – autophagy being the process the cell uses to clear unwanted damaging proteins.

Present Investigation Status and Expert Assessments

Upon examining current studies on light therapy for dementia, he states, approximately 400 participants enrolled in multiple trials, including his own initial clinical trials in the US