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Phototherapy is definitely experiencing a surge in popularity. There are now available light-emitting tools for everything from complexion problems and aging signs to aching tissues and gum disease, the newest innovation is a dental hygiene device outfitted with small red light diodes, promoted by the creators as “a breakthrough in at-home oral care.” 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 infrared radiation heats your body itself. Based on supporter testimonials, it feels similar to a full-body light therapy session, enhancing collagen production, soothing sore muscles, relieving inflammation and long-term ailments and potentially guarding against cognitive decline.

Understanding the Evidence

“It feels almost magical,” observes a Durham University professor, professor in neuroscience at Durham University and a convert to the value of light therapy. Naturally, some of light’s effects on our bodies are well established. Sunlight helps us make vitamin D, crucial for strong bones, immune defense, and tissue repair. Natural light synchronizes our biological clocks, too, activating brain chemicals and hormonal responses in daylight, and winding down bodily functions for sleep as it fades into night. Sunlight-imitating lamps are a common remedy for people with seasonal affective disorder (Sad) to boost low mood in winter. Clearly, light energy is essential for optimal functioning.

Various Phototherapy Approaches

While Sad lamps tend to use a mixture of light frequencies from the blue end of the spectrum, the majority of phototherapy tools use red or near-infrared wavelengths. In serious clinical research, such as Chazot’s investigations into the effects of infrared on brain cells, identifying the optimal wavelength is crucial. Photons represent electromagnetic waves, which runs the spectrum from the lowest-energy, longest wavelengths (radio waves) to high-energy gamma radiation. Therapeutic light application utilizes intermediate light frequencies, 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).

Dermatologists have utilized UV therapy for extensive periods to treat chronic skin conditions such as eczema, psoriasis and vitiligo. It works on the immune system within cells, “and suppresses swelling,” explains a dermatology expert. “There’s lots of evidence for phototherapy.” UVA reaches deeper skin layers compared to UVB, in contrast to LEDs in commercial products (typically emitting red, infrared or blue wavelengths) “typically have shallower penetration.”

Risk Assessment and Professional Supervision

UVB radiation effects, including sunburn or skin darkening, are recognized but medical equipment uses controlled narrow-band delivery – indicating limited wavelength spectrum – which minimises the risks. “It’s supervised by a healthcare professional, meaning intensity is regulated,” explains the dermatologist. Essentially, the devices are tuned by qualified personnel, “to confirm suitable light frequency output – different from beauty salons, where regulations may be lax, and emission spectra aren’t confirmed.”

Consumer Devices and Evidence Gaps

Colored light diodes, he notes, “aren’t really used in the medical sense, but could assist with specific concerns.” Red LEDs, it is proposed, improve circulatory function, oxygen uptake and cell renewal in the skin, and activate collagen formation – an important goal for anti-aging. “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, ideal distance from skin surface, the risk-benefit ratio. Many uncertainties remain.”

Targeted Uses and Expert Opinions

Early blue-light applications focused on skin microbes, microorganisms connected to breakouts. Research support isn’t sufficient for standard medical recommendation – even though, says Ho, “it’s frequently employed in beauty centers.” Certain patients incorporate it into their regimen, he says, however for consumer products, “we advise cautious experimentation and safety verification. Unless it’s a medical device, the regulation is a bit grey.”

Cutting-Edge Studies and Biological Processes

At the same time, in advanced research areas, scientists have been studying cerebral tissue, discovering multiple mechanisms for infrared’s cellular benefits. “Pretty much everything I did with the light at that particular wavelength was positive and protective,” 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, but over 20 years ago, a physician creating light-based cold sore therapy requested his biological knowledge. “He designed tools for biological testing,” he explains. “I was pretty sceptical. This particular frequency was around 1070 nanometers, that many assumed was biologically inert.”

Its beneficial characteristic, however, was that it travelled through water easily, 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 are the powerhouses of cells, producing fuel for biological processes. “Every cell in your body has mitochondria, even within brain tissue,” says Chazot, who concentrated on cerebral applications. “Research confirms improved brain blood flow with phototherapy, which is always very good.”

With 1070 treatment, mitochondria also produce a small amount of a molecule known as reactive oxygen species. In low doses this substance, notes the scientist, “triggers guardian proteins that maintain organelle health, protect cellular integrity and manage defective proteins.”

Such mechanisms indicate hope for cognitive disorders: free radical neutralization, swelling control, and waste removal – autophagy representing cellular waste disposal.

Ongoing Study Progress and Specialist Evaluations

Upon examining current studies on light therapy for dementia, he says, about 400 people were taking part in four studies, including his own initial clinical trials in the US