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Light therapy is definitely experiencing a surge in popularity. You can now buy light-emitting tools for everything from skin conditions and wrinkles as well as aching tissues and gum disease, recently introduced is an oral care tool enhanced with small red light diodes, marketed by the company as “a major advance in personal mouth health.” Worldwide, the market was worth $1bn in 2024 and is projected to grow to $1.8bn by 2035. Options include full-body infrared sauna sessions, that employ light waves rather than traditional heat sources, the infrared radiation heats your body itself. According to its devotees, the experience resembles using an LED facial mask, boosting skin collagen, relaxing muscles, relieving inflammation and chronic health conditions and potentially guarding against cognitive decline.

Understanding the Evidence

“It sounds a bit like witchcraft,” notes a Durham University professor, a scientist who has studied phototherapy extensively. Certainly, some of light’s effects on our bodies are well established. Our bodies produce vitamin D through sun exposure, needed for bone health, immunity, muscles and more. Sunlight regulates our circadian rhythms, too, activating brain chemicals and hormonal responses in daylight, and signaling the body to slow down for nighttime. Daylight-simulating devices 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.

Types of Light Therapy

Whereas seasonal affective disorder devices typically employ blue-range light, most other light therapy devices deploy red or infrared light. In serious clinical research, including research on infrared’s impact on neural cells, determining the precise frequency is essential. Light constitutes electromagnetic energy, spanning from low-energy radio waves 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 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 modulates intracellular immune mechanisms, “and suppresses swelling,” explains Dr Bernard Ho. “There’s lots of evidence for phototherapy.” UVA penetrates skin more deeply than UVB, while the LEDs in consumer devices (typically emitting red, infrared or blue wavelengths) “tend to be a bit more superficial.”

Risk Assessment and Professional Supervision

The side-effects of UVB exposure, including sunburn or skin darkening, are understood but clinical devices employ restricted wavelength ranges – meaning smaller wavelengths – which decreases danger. “Therapy is overseen by qualified practitioners, thus exposure is controlled,” says Ho. And crucially, the lightbulbs are calibrated by medical technicians, “to confirm suitable light frequency output – unlike in tanning salons, where oversight might be limited, and emission spectra aren’t confirmed.”

Commercial Products and Research Limitations

Colored light diodes, he notes, “don’t have strong medical applications, but could assist with specific concerns.” Red wavelength therapy, proponents claim, help boost blood circulation, oxygen utilization and cell renewal in the skin, and activate collagen formation – a primary objective in youth preservation. “The evidence is there,” states the dermatologist. “But it’s not conclusive.” Regardless, amid the sea of devices now available, “we’re uncertain whether commercial devices replicate research conditions. Optimal treatment times are unknown, ideal distance from skin surface, if benefits outweigh potential risks. There are lots of questions.”

Specific Applications and Professional Perspectives

One of the earliest blue-light products targeted Cutibacterium acnes, bacteria linked to pimples. The evidence for its efficacy isn’t strong enough for it to be routinely prescribed by doctors – despite the fact that, notes the dermatologist, “it’s often seen in medical spas or aesthetics practices.” Individuals include it in their skincare practices, he observes, though when purchasing home devices, “we recommend careful testing and security confirmation. If it’s not medically certified, the regulation is a bit grey.”

Innovative Investigations and Molecular Effects

Simultaneously, in advanced research areas, researchers have been testing neural cells, revealing various pathways for light-enhanced cell function. “Virtually all experiments with specific wavelengths showed beneficial and safeguarding effects,” he states. It is partly these many and varied positive effects on cellular health that have driven skepticism about light therapy – that claims seem exaggerated. However, scientific investigation has altered his perspective.

The researcher primarily focuses on pharmaceutical solutions for brain disorders, however two decades past, a doctor developing photonic antiviral treatment consulted his scientific background. “He developed equipment for cellular and insect experiments,” he recalls. “I was pretty sceptical. This particular frequency was around 1070 nanometers, which most thought had no biological effect.”

What it did have going for it, nevertheless, 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, creating power for cellular operations. “All human cells contain mitochondria, even within brain tissue,” notes the researcher, who, as a neuroscientist, decided to focus the research on brain cells. “Research confirms improved brain blood flow with phototherapy, which is generally advantageous.”

With specific frequency application, energy organelles generate minimal reactive oxygen compounds. At controlled levels these compounds, notes the scientist, “activates protective proteins that safeguard mitochondria, protect cellular integrity and manage defective proteins.”

Such mechanisms indicate hope for cognitive disorders: oxidative protection, anti-inflammatory, and pro-autophagy – autophagy being the process the cell uses to clear unwanted damaging proteins.

Present Investigation Status and Expert Assessments

The last time Chazot checked the literature on using the 1070 wavelength on human dementia patients, he states, about 400 people were taking part in four studies, including his own initial clinical trials in the US