I have to wonder if sitting by a fire at night is analogous.
[1] "Measuring and predicting eyelid spectral transmittance" Journal of Biomedical Optics, Vol. 16, Issue 6, 067011 (June 2011) https://doi.org/10.1117/1.3593151
Bright enough to warm the body, but not thermally stress the cells.
And yeah, closing your eyelids would block UV light from getting in and cross linking proteins and causing cataracts, while still allowing for NIR light to get in and speed up the mitochondria.
Analogous for sure
Some believe that the reason red light helps is that cytochrome C oxidase can use the red light to convert serotonin to melatonin and that melatonin is the most important anti-oxidant in the human body. (Under this model, melatonin cannot get into the mitochondria, but serotonin can.)
What little I remember it sure fits your description. I might try hooking up a red heat lamp to a timer as an alarm clock to see what happens.
have occasional pain in my left knee, but resolved it by one or two really hot
sessions at the chimney(I nearly burned myself lol so it has to be really hot in
order to get rid of chronical pain). Knee pain is gone now. I have read a theory
of the vagus nerve sending harmful substances produced by the microbiome in the
bowels to the knee to prevent it going to the brain. The useful compounds get
teleported to the brain(we got no clue how the vagus nerve does it, but if you
lack a functioning vagus nerve the transportation ceases).
I suspect because the longer IR wavelengths just heat the body up, it's hard to get enough of the more "useful" wavelengths without overheating
It has UV, which stresses out the cells You can't PWM the sun, it's hard to get full naked coverage in front of it. Doesn't perfectly target NIR or NIR-II biological windows.
But for a base/starter, it can't be beat.
Simply put, light is better than no light.