‘It sounds like witchcraft’: can light therapy really give you better skin, cleaner teeth, stronger joints?

From infrared saunas to LED beauty masks, a billion-dollar market has grown around the healing power of light. But where does the science end and the hype begin?

Light therapy is certainly having a moment. You can now buy glowing gadgets for everything from skin conditions and wrinkles to sore muscles and gum disease, the latest being a toothbrush enhanced with tiny red LEDs, described by its makers 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, your body is warmed directly by infrared light. According to its devotees, it’s like bathing in one of those LED-lit beauty masks, boosting skin collagen, relaxing muscles, relieving inflammation and chronic health conditions while protecting against dementia.

“It sounds a bit like witchcraft,” says Paul Chazot, professor in neuroscience at Durham University and a convert to the value of light therapy following 20 years of research in the field. Of course, some of light’s effects on our bodies are well established. Sunlight helps us make vitamin D, needed for bone health, immunity, muscles and more. Sunlight regulates our circadian rhythms, too, triggering the release of neurochemicals and hormones while we are awake, 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. So there’s no doubt we need light energy to function well.