From the trial data https://clinicaltrials.gov/ct2/show/NCT03677206 From an article in Pain New: https://www.painnewsnetwork.org/sto...-light-therapy-improves-fibromyalgia-symptoms There is rat data, but on human "blinding" of green light vs. white light, it isn't blinded. The clinical trial stated that the participants weren't told which LED light was the experimental one. (They could google it and find out.) Is just walking (for those who can) in the woods under a tree canopy getting a dose of green light?
Both LED light colours led to "statistically significant decrease" in headache symptoms and on the pain scale. https://pubmed.ncbi.nlm.nih.gov/32903062/ The magnitude of effect was larger in the green LED group, but this could simply be due to increased response biases, since no objective outcomes were used.
Hmmm. Do we know how colour temperature affects human cells? We know a bit about blue light, and use of blue glasses , but anything else? Coloured LEDs are transforming agriculture, enabling modulation of yield, ( in cannabis growing its used re strength of THC), rate of senescence , growth rates...... It is not just the nature of the light but the timing and duration which modulate effects and it varies for different species. Has there been much research outwith plants? ETA article link https://bioslighting.com/horticulture-lighting/grow-light-spectrum-led-plants/
Red and Near infrared light have been studied a bit, I know I've read about it in regards to joint inflammation, wound healing, sports and restitution. Also some cell culture studies. Not feeling up to go looking for sources just now.
My home-made FIR sauna got rid of my neck pain back in 2000-2001. I had pain for months, and after one session the pain was gone.
If you define green light as a certain narrow part of the spectrum, then yes, but you'll get more in direct sunlight. If you want to define 'green light' for medical therapy as magnitude in that part of the spectrum and nearly no magnitude in the rest of the spectrum, then no, forest shade won't count. Sounds like nonsense to me. I remember scams with an ordinary light bulb in a box with some coloured filters, with really extravagant claims for curing diseases. Same old, same old, just with LEDs instead of incandescent bulbs.
Here's an article from the U of Arizona about the impetus of the study (sitting under the forest canopy, indeed) https://news.arizona.edu/story/treatment-pain-gets-green-light Science a bit sketchy, in my humble and rather uninformed opinion.