Summary
Hosts Tegan Taylor and Dr. Norman Swan walk through the electromagnetic spectrum from infrared to ultraviolet, examining the health claims around different colors of light. They cover infrared saunas and how they use light rather than steam to create heat, experimental near-infrared cancer treatments that activate tumor-targeting antibodies, and the NASA observation that led to red and blue LED therapy for wound healing and skin rejuvenation. The episode takes a skeptical, evidence-based approach to light therapy claims. They discuss how red light may stimulate fibroblasts for collagen production but note the evidence is thin with few randomized trials. Blue light shows a small effect on acne but existing treatments work better. White light therapy has some evidence for seasonal affective disorder through circadian rhythm reset. UV light is used for psoriasis treatment but carries skin cancer risk. The most well-established use of light therapy discussed is phototherapy for neonatal jaundice, which breaks down bilirubin in the skin to prevent brain damage.
Key Points
- Infrared saunas use light rather than steam to create heat, perceived by the body as warmth through increased molecular movement
- Near-infrared light is being experimentally used in cancer treatment to activate tumor-targeting antibody-drug combinations
- NASA scientists observed faster wound healing in hands exposed to red and blue light while growing potato plants in space
- Red light may stimulate fibroblasts for collagen production, but evidence from randomized controlled trials is thin
- Blue light shows a small effect on acne by sterilizing skin bacteria, but existing therapies have larger effect sizes
- White light therapy can help prevent seasonal affective disorder by resetting circadian rhythm and melatonin production
- UV light therapy (PUVA) is used for psoriasis but increases skin cancer risk, requiring careful dosing
- Phototherapy for neonatal jaundice is the most well-established medical use of light, breaking down bilirubin to prevent brain damage
Key Moments
Near-infrared light for experimental cancer treatment
Near-infrared light is being used experimentally to activate tumor-targeting antibody-drug combinations, offering a way to treat tumors inaccessible to surgery or standard chemotherapy.
"Yeah, it's experimental at the moment, but you get a chemical that's activated by near-infrared light. You attach an antibody to it, and that antibody is specific to the tumour you're trying to attack. But it's relatively inactive until it's exposed to near-infrared light. So you inject the drug into the body, you then expose the person to near-infrared light. So you inject the drug into the body, you then expose the person to near-infrared light, it gets activated, goes to the tumour and helps to destroy the tumour."
NASA discovery of red light wound healing
NASA scientists growing potato plants in space noticed cuts on their hands healed faster under red and blue LED light, sparking research into light therapy for skin healing and the development of LED face masks.
"it was an observation from NASA scientists working in space where they were growing potato plants in zero gravity. And to help the potato plants to grow, they expose the plants to red and blue light because that's part of the spectrum of light that doesn't get reflected by the leaves. That's why leaves look green to us is because they're reflecting the green light. And so the scientists were working with their hands on these potato plants and they seem to notice that any cuts on their hands healed faster when they were under the light."
Limited evidence for red light collagen stimulation
While red light theoretically stimulates fibroblasts to produce collagen, the evidence from randomized controlled trials remains thin and the hosts caution against expensive purchases.
"The evidence is thin. Theoretically, it could work, but there have been very few randomized trials."
White light therapy for seasonal affective disorder
Bright white light exposure in the morning can help prevent seasonal affective disorder by resetting melatonin and the body clock, though research quality in this area is mixed.
"It's usually in winter. Some people can get it in other seasons as well. And what light therapy does there is readjusts the circadian rhythm and in a sense extends the day. And it's usually exposure to bright white light in the morning. And this can be through a light box, which comes on and simulates the dawn. There's different ways of doing this. And sometimes it's used to prevent seasonal affective disorder, which is essentially depression and low mood."
