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Phototherapy is clearly enjoying a wave of attention. You can now buy light-emitting tools designed to address dermatological concerns and fine lines to sore muscles and gum disease, the newest innovation is an oral care tool outfitted with small red light diodes, described by its makers as “a breakthrough for domestic dental hygiene.” 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, where instead of hot coals (real or electric) heating the air, the infrared radiation heats your body itself. According to its devotees, the experience resembles using an LED facial mask, stimulating skin elasticity, easing muscle tension, reducing swelling and chronic health conditions as well as supporting brain health.

Understanding the Evidence

“It sounds a bit like witchcraft,” notes a Durham University professor, who has researched light therapy for two decades. Certainly, we know light influences biological functions. Our bodies produce vitamin D through sun exposure, essential for skeletal strength, immune function, and muscular health. Light exposure controls our sleep-wake cycles, too, triggering the release of neurochemicals and hormones while we are awake, and preparing the body for rest as darkness falls. Daylight-simulating devices frequently help individuals with seasonal depression to boost low mood in winter. Clearly, light energy is essential for optimal functioning.

Types of Light Therapy

Although mood lamps generally utilize blue-spectrum frequencies, consumer light therapy products mostly feature red and infrared emissions. In serious clinical research, like examinations of infrared influence on cerebral tissue, identifying the optimal wavelength is crucial. Photons represent electromagnetic waves, spanning from low-energy radio waves to the highest-energy (gamma waves). Phototherapy, or light therapy employs mid-spectrum wavelengths, with ultraviolet representing the higher energy invisible light, followed by visible light encompassing rainbow colors and then infrared (which we can see with night-vision goggles).

Dermatologists have utilized UV therapy for extensive periods to manage persistent skin disorders including eczema and psoriasis. It affects cellular immune responses, “and suppresses swelling,” says a skin specialist. “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) “tend to be a bit more superficial.”

Safety Considerations and Medical Oversight

The side-effects of UVB exposure, such as burning or tanning, are recognized but medical equipment uses controlled narrow-band delivery – indicating limited wavelength spectrum – which decreases danger. “It’s supervised by a healthcare professional, meaning intensity is regulated,” notes the specialist. And crucially, the lightbulbs are calibrated by medical technicians, “to ensure that the wavelength that’s being delivered is fit for purpose – different from beauty salons, where oversight might be limited, and we don’t really know what wavelengths are being used.”

Home Devices and Scientific Uncertainty

Colored light diodes, he says, “don’t have strong medical applications, but they may help with certain conditions.” Red light devices, some suggest, improve circulatory function, oxygen utilization and cell renewal in the skin, and promote collagen synthesis – a key aspiration in anti-ageing effects. “Research exists,” states the dermatologist. “But it’s not conclusive.” Nevertheless, given the plethora of available tools, “it’s unclear if device outputs match study parameters. Optimal treatment times are unknown, ideal distance from skin surface, the risk-benefit ratio. Numerous concerns persist.”

Specific Applications and Professional Perspectives

One of the earliest blue-light products targeted Cutibacterium acnes, bacteria linked to pimples. Scientific backing remains inadequate for regular prescription – despite the fact that, notes the dermatologist, “it’s often seen in medical spas or aesthetics practices.” Some of his patients use it as part of their routine, he observes, but if they’re buying a device for home use, “we recommend careful testing and security confirmation. Without proper medical classification, standards are somewhat unclear.”

Innovative Investigations and Molecular Effects

Meanwhile, in innovative scientific domains, scientists have been studying cerebral tissue, identifying a number of ways in which infrared can boost cellular health. “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. Yet, experimental evidence has transformed his viewpoint.

Chazot mostly works on developing drug treatments for neurodegenerative diseases, though twenty years earlier, a physician creating light-based cold sore therapy requested his biological knowledge. “He developed equipment for cellular and insect experiments,” he recalls. “I was pretty sceptical. It was an unusual wavelength of about 1070 nanometres, that many assumed was biologically inert.”

The advantage it possessed, however, was its efficient water penetration, allowing substantial bodily 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, particularly in neural cells,” notes the researcher, who, as a neuroscientist, decided to focus the research on brain cells. “It has been shown that in humans this light therapy increases blood flow into the brain, which is consistently beneficial.”

Using 1070nm wavelength, cellular power plants create limited oxidative molecules. At controlled levels these compounds, explains the expert, “activates protective proteins that safeguard mitochondria, protect cellular integrity and manage defective proteins.”

Such mechanisms indicate hope for cognitive disorders: antioxidant, anti-inflammatory, and pro-autophagy – self-digestion mechanisms eliminating harmful elements.

Current Research Status and Professional Opinions

Upon examining current studies on light therapy for dementia, he reports, several hundred individuals participated in various investigations, comprising his early research projects