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Phototherapy is definitely experiencing a surge in popularity. Consumers can purchase illuminated devices for everything from complexion problems and aging signs as well as sore muscles and oral inflammation, recently introduced is a toothbrush equipped with small red light diodes, promoted by the creators as “a major advance for domestic dental hygiene.” Internationally, 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, that employ light waves rather than traditional heat sources, your body is warmed directly by infrared light. According to its devotees, it feels similar to a full-body light therapy session, enhancing collagen production, relaxing muscles, alleviating inflammatory responses and chronic health conditions as well as supporting brain health.

Understanding the Evidence

“It sounds a bit like witchcraft,” says a Durham University professor, professor in neuroscience at Durham University and a convert to the value of light therapy. Certainly, some of light’s effects on our bodies are well established. Sunlight helps us make vitamin D, essential for skeletal strength, immune function, and muscular health. Sunlight regulates our circadian rhythms, as well, stimulating neurotransmitter and hormone production during daytime, and signaling the body to slow down for nighttime. Artificial sun lamps are a common remedy for people with seasonal affective disorder (Sad) to boost low mood in winter. Undoubtedly, light plays a vital role in human health.

Various Phototherapy Approaches

While Sad lamps tend to use a mixture of light frequencies from the blue end of the spectrum, most other light therapy devices deploy red or infrared light. During advanced medical investigations, such as Chazot’s investigations into the effects of infrared on brain cells, determining the precise frequency is essential. Photons represent electromagnetic waves, spanning from low-energy radio waves to high-energy gamma radiation. Therapeutic light application employs mid-spectrum wavelengths, including invisible ultraviolet radiation, 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 affects cellular immune responses, “and reduces inflammatory processes,” explains Dr Bernard Ho. “Considerable data validates phototherapy.” UVA reaches deeper skin layers compared to UVB, in contrast to LEDs in commercial products (typically emitting red, infrared or blue wavelengths) “tend to be a bit more superficial.”

Safety Considerations and Medical Oversight

UVB radiation effects, such as burning or tanning, are understood but clinical devices employ restricted wavelength ranges – indicating limited wavelength spectrum – which decreases danger. “It’s supervised by a healthcare professional, so the dosage is monitored,” says Ho. Most importantly, the devices are tuned by qualified personnel, “to confirm suitable light frequency output – 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

Red and blue light sources, he notes, “aren’t really used in the medical sense, though they might benefit some issues.” Red wavelength therapy, proponents claim, enhance blood flow, oxygen absorption and cell renewal in the skin, and promote collagen synthesis – a primary objective in youth preservation. “The evidence is there,” states the dermatologist. “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, whether or not that will increase the risk versus the benefit. There are lots of questions.”

Treatment Areas and Specialist Views

Initial blue-light devices addressed acne bacteria, microorganisms connected to breakouts. Research support isn’t sufficient for standard medical recommendation – despite the fact that, says Ho, “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, oversight remains ambiguous.”

Innovative Investigations and Molecular Effects

Simultaneously, in a far-flung field of pioneering medical science, researchers have been testing neural cells, identifying a number of ways in which infrared can boost cellular health. “Virtually all experiments with specific wavelengths showed beneficial and safeguarding effects,” he says. Multiple claimed advantages have created skepticism toward light treatment – that results appear unrealistic. However, scientific investigation has altered his perspective.

Chazot mostly works on developing drug treatments for neurodegenerative diseases, however two decades past, a physician creating light-based cold sore therapy requested his biological knowledge. “He created some devices so that we could work with them with cells and with fruit flies,” he says. “I was quite suspicious. The specific wavelength measured approximately 1070nm, that nobody believed did anything biological.”

What it did have going for it, though, was its ability to transmit through aqueous environments, enabling deeper tissue penetration.

Mitochondrial Effects and Brain Health

Growing data suggested infrared influenced energy-producing organelles. Mitochondria are the powerhouses of cells, generating energy for them to function. “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 always very good.”

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

Such mechanisms indicate hope for cognitive disorders: antioxidant, inflammation reduction, and pro-autophagy – autophagy being the process the cell uses to clear unwanted damaging proteins.

Current Research Status and Professional Opinions

The last time Chazot checked the literature on using the 1070 wavelength on human dementia patients, he reports, about 400 people were taking part in four studies, comprising his early research projects