Was your post aimed at me? I was responding to Joseph, and he asked a question about a 180F sauna. So I assumed this was an infrared sauna (but I might have been wrong in that assumption). Infrared Sauna’s commonly use wavelengths in the FIR spectrum - albeit sometimes a hybrid combination of NIR and FIR is used.
Plus, as mentioned in my post: there are multiple publications discussing MMP activation upon excessive NIR (and/or MIR and/or FIR) exposure. I listed only a few of them, but as said: there are multiple other publications available.
I also mentioned that the problem with these publications is that in different studies very different parameters are used - including at moments very high doses of NIR (or MIR or FIR, or a combination). So as said: with all these different (combinations of) wavelengths, intensity levels and devices used, it’s difficult to draw conclusions, and I follow a personal approach out of caution that others might not agree with. I do so, since imo we simply don’t seem to know yet what doses and spectral wavelengths are optimal.
Indeed, the second publication used a combination of IRA and IRB. We’ve been discussing several things in this thread. Joseph mentioned a sauna (IR saunas as mentioned quite commonly use FIR). And in the first Podcast Scott Zimmerman pointed out that research suggests we are in fact ‘missing out’ on most of the IR spectrum with the LEDs most of us use indoors. He suggested that possibly not the blue light in itself, but this imbalance between blue and NIR light that a lot of people are constantly exposed to indoors, might be suboptimal for health. Thus I’ve bought a heat lamp to try to somewhat ‘replicate’ the solar spectrum. Besides emitting light in the IRA spectrum, this lamp also emits IRB and a small portion of IRC. So this differs from Photobiomodulation PBM, that you are referring to, and that indeed is also discussed throughout the thread. (In earlier studies mostly described as LLLT). I will say that over the years I’ve read publications discussing that IRA, IRB and IRC can increase MMP activation, not just IRB or IRC. So it’s not just as simple as ‘pick the right wavelenghts’, and my personal interpretation has been it’s more a question of ‘optimal dosing’ to avoid the biphasic response discussed in research.
Having said all that, concerning PBM, in the first Podcast Zimmerman also pointed out that it is unlikely that it is most optimal to only use these specific few wavelengths that are most commonly used in PBM (650, 680, 850nm 1050nm etc). But these are just the LED diodes that are readily available based on among others existing semiconductor technology. These are most often used in research as a result. He suggested balance was key, in other words, and how in that sense outdoor light is optimal.
All in all, I have been wondering myself about different wavelengths (including IRA but also IRB and IRC) and among others their effects on skin. And the studies I’ve seen over the years don’t give a solid answer, given all these different parameters that are used, as mentioned.
This study below for example uses IRA, but also in the spectrum 700 - 1400nm. Again, you can now argue that it also uses light in the 900-1000nm spectrum, which some, but not all PBM panels cover. Besides that, high doses were used. One would have to be out in the sun in summertime around the equator for hours to get similar amounts of NIR exposure. And that’s exactly what I said in my post: I haven’t been able to find a body of research wherein comparable parameters are used, and that thus more solid conclusions can be drawn from. But as said I have taken a personal approach with more moderate exposure than I see a lot of other people do, that I’m sure others may disagree with.
Frankly I also don’t want to get into long discussions about that, as we’ve been there before in the prior thread, and while I understand your criticism that you voiced in that thread also, since so many different parameters are used in available research: I’d rather have people would post and discuss more studies that could bring more clarity. Because I’ve looked over quite a few publications, also years ago, but I feel there are no solid conclusion to be drawn yet when it comes to optimal parameters, doses, and the biphasic response - and thus potential adverse effects.
[https://www.sciencedirect.com/science/article/pii/S0022202X15336241] Infrared Radiation-Induced Matrix Metalloproteinase in Human Skin: Implications for Protection)