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Phototherapy is definitely experiencing a surge in popularity. Consumers can purchase glowing gadgets for everything from skin conditions and wrinkles along with sore muscles and oral inflammation, the latest being a dental hygiene device outfitted with tiny red LEDs, marketed by the company as “a breakthrough in personal mouth health.” Globally, 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 feels similar to a full-body light therapy session, stimulating skin elasticity, relaxing muscles, relieving inflammation and persistent medical issues and potentially guarding against cognitive decline.

The Science and Skepticism

“It sounds a bit like witchcraft,” notes a neuroscience expert, professor in neuroscience at Durham University and a convert to the value of light therapy. Certainly, we know light influences biological functions. Sunlight helps us make vitamin D, needed for bone health, immunity, muscles and more. Sunlight regulates our circadian rhythms, as well, activating brain chemicals and hormonal responses in daylight, and winding down bodily functions for sleep as it fades into night. Daylight-simulating devices are standard treatment for winter mood disorders to combat seasonal emotional slumps. So there’s no doubt we need light energy to function well.

Types of Light Therapy

Although mood lamps generally utilize blue-spectrum frequencies, consumer light therapy products mostly feature red and infrared emissions. During advanced medical investigations, such as Chazot’s investigations into the effects of infrared on brain cells, finding the right frequency is key. Light is a form of electromagnetic radiation, extending from long-wavelength radiation to the highest-energy (gamma waves). Light-based treatment uses wavelengths around the middle of this spectrum, including invisible ultraviolet radiation, then the visible spectrum we perceive as colors and finally infrared detectable with special equipment.

Ultraviolet treatment has been employed by skin specialists for decades to treat chronic skin conditions such as eczema, psoriasis and vitiligo. It modulates intracellular immune mechanisms, “and dampens down inflammation,” explains a dermatology expert. “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) “generally affect surface layers.”

Safety Protocols and Medical Guidance

UVB radiation effects, including sunburn or skin darkening, are recognized but medical equipment uses controlled narrow-band delivery – meaning smaller wavelengths – which minimises the risks. “It’s supervised by a healthcare professional, meaning intensity is regulated,” says Ho. Most importantly, the light sources are adjusted by technical experts, “to confirm suitable light frequency output – as opposed to commercial tanning facilities, where oversight might be limited, and wavelength accuracy isn’t verified.”

Commercial Products and Research Limitations

Colored light diodes, he says, “aren’t typically employed clinically, but could assist with specific concerns.” Red wavelength therapy, proponents claim, help boost blood circulation, oxygen utilization and dermal rejuvenation, and stimulate collagen production – an important goal for anti-aging. “The evidence is there,” states the dermatologist. “But it’s not conclusive.” Regardless, with numerous products on the market, “it’s unclear if device outputs match study parameters. We don’t know the duration, how close the lights should be to the skin, whether or not that will increase the risk versus the benefit. Many uncertainties remain.”

Targeted Uses and Expert Opinions

Early blue-light applications focused on skin microbes, a microbe associated with acne. The evidence for its efficacy isn’t strong enough for it to be routinely prescribed by doctors – even though, notes the dermatologist, “it’s commonly used in cosmetic clinics.” Some of his patients use it as part of their routine, he says, however for consumer products, “we just tell them to try it carefully and to make sure it has been assessed for safety. Unless it’s a medical device, oversight remains ambiguous.”

Advanced Research and Cellular Mechanisms

Simultaneously, in advanced research areas, Chazot has been experimenting with brain cells, 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 it’s too good to be true. But his research has thoroughly changed his mind in that respect.

Chazot mostly works on developing drug treatments for neurodegenerative diseases, however two decades past, a doctor developing photonic antiviral treatment consulted his scientific background. “He created some devices so that we could work with them with cells and with fruit flies,” he recalls. “I was quite suspicious. It was an unusual wavelength of about 1070 nanometres, that many assumed was biologically inert.”

Its beneficial characteristic, however, was that it travelled through water easily, 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. These organelles generate cellular energy, producing fuel for biological processes. “Mitochondria exist throughout the body, including the brain,” says Chazot, who concentrated on cerebral applications. “Research confirms improved brain blood flow with phototherapy, which is generally advantageous.”

Using 1070nm wavelength, mitochondria also produce a small amount of a molecule known as reactive oxygen species. In low doses this substance, says Chazot, “activates protective proteins that safeguard mitochondria, preserve cell function and eliminate damaged proteins.”

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

Ongoing Study Progress and Specialist Evaluations

When recently reviewing 1070nm research for cognitive decline, he reports, approximately 400 participants enrolled in multiple trials, comprising his early research projects