Hey guys, did you catch the post last night with the snippet from Brad Miller’s interview with Tucker Carlson. If you missed it, here it is!!! Go Brad!
As a starting point I asked perplexity AI to provide me with studies, here is the answer:
Your conclusion about receiving beneficial near-infrared (NIR) light exposure through a closed window on semi-overcast days, even while fully clothed, is partially supported by available research. Here are the key points from studies relevant to your observations:
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Ordinary glass allows significant transmission of NIR light, though the exact percentage depends on the type of glass. For instance, laminated glass transmits less NIR compared to tempered or ordinary glass113.
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Glass blocks most UVB radiation and transmits varying amounts of UVA depending on its composition. Laminated glass offers better UV protection than tempered glass111.
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NIR light can penetrate biological tissues and materials, including clothing, depending on factors like wavelength and material thickness. Studies show that wavelengths in the 750–900 nm range have minimal absorption by water and other tissue components, allowing deeper penetration23. However, dense fabrics like denim can significantly reduce NIR transmission.
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Clouds reduce incoming solar radiation, including NIR, but do not block it entirely. Depending on cloud thickness and type, up to 50% of NIR radiation may still reach the surface68. This aligns with your observation that semi-overcast conditions still allow for beneficial exposure.
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Photobiomodulation (PBM) using NIR light has been shown to improve cellular metabolism by stimulating cytochrome c oxidase in mitochondria. This process enhances ATP production and reduces oxidative stress49. Studies also suggest that regular exposure to NIR can improve mood, reduce inflammation, and support overall well-being, particularly in low-sunlight conditions like winter910.
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Removing screens or barriers behind windows may enhance NIR exposure since materials like metal or plastic can block or absorb solar rays.
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While clothing does not entirely block NIR light, lighter and thinner fabrics allow for better penetration compared to dense or dark materials. Green clothing may impede absorption due to its reflective properties in the NIR spectrum.
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While sitting behind a south-west-facing window can provide some heliotherapy benefits, the intensity of NIR exposure will depend on factors like time of day, angle of sunlight, and window properties.
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Certain studies suggest that low-level NIR penetration through skin is limited unless higher power densities are used (e.g., lasers)3. This might reduce the effectiveness of passive sunlight exposure compared to direct outdoor sessions.
In summary, your approach to heliotherapy through a closed window on semi-overcast days is reasonable for moderate benefits. However, for optimal results, direct sunlight exposure without barriers like glass or heavy clothing would be more effective.
Studies mentioned included
They seem to largely support your understanding.