The core argument here is specific and worth stating plainly: near infrared light is not the same as far infrared light, and that distinction matters biologically. Far infrared saunas — the kind you'll find in most commercial wellness centers — heat the body from the surface inward. Near infrared light, operating at wavelengths between roughly 700 and 1400 nanometers, penetrates biological tissue up to 100 millimeters. That's not a marketing claim. That's physics. Water absorbs far infrared aggressively, which is why it can't go deep. Near infrared travels through water, through skin, through fat, into muscle tissue and organs.
The second claim — the one that connects this to mitochondrial health — is where it gets genuinely interesting. Mitochondria have light-sensitive proteins. Cytochrome c oxidase, the terminal enzyme in the electron transport chain, has absorption peaks in the near infrared range. When NIR light hits it, you get measurable improvements in electron flow, ATP production, and a reduction in reactive oxygen species. This isn't speculative. There's a substantial body of photobiomodulation research behind it.
The far infrared sauna literature is well established. The Finnish population studies — nearly 1,700 participants tracked over years — show dose-dependent reductions in cardiovascular mortality, all-cause mortality, and neurodegenerative disease. That data is for conventional Finnish-style dry saunas and commercial far infrared units. It's powerful evidence. But those studies measure outcomes, not mechanisms. They tell us that heat exposure works. They don't tell us which frequencies of light are doing the most work.
In our knowledge base, the Therasage interview with Rob Besner covers similar ground — the idea that infrared light is doing something distinct from simple heat transfer. Vic Riffel's conversation on sunlight saunas makes a parallel point about spectral quality. What they're all circling is the same truth: the biological response to a sauna isn't just about raising core temperature. The light itself carries information.
The honest disagreement in this space is about dose and delivery. Richards argues that incandescent bulbs are the optimal source — 250-watt lamps that produce a broad spectrum including significant NIR output. Other researchers prefer targeted LED panels at specific therapeutic wavelengths, typically 660nm red and 850nm NIR. The mechanism is the same. The delivery differs. Neither camp has enough head-to-head clinical trials to call it definitively.
There's also a reasonable question about whether the photobiomodulation effects you get from a lamp-based sauna are additive to the heat effects, or whether the heat is doing most of the heavy lifting regardless of spectral content. My read of the available evidence: probably both are contributing, and separating them cleanly is methodologically difficult.
If you have access to a near infrared sauna — use it. The mitochondrial mechanisms are real, the penetration depth is real, and the photobiomodulation research is credible. Three sessions per week, 20 to 30 minutes each. The temperature doesn't need to be as extreme as a traditional Finnish sauna; you're not relying purely on convective heat.
If you only have access to far infrared, don't stress. The outcome data is on your side. You're still getting substantial cardiovascular, metabolic, and neurological benefits.
Here's what strikes me most about this conversation: we've spent the last 30 years systematically removing near infrared light from our environment. We replaced incandescent bulbs — which emit substantial NIR — with fluorescent and LED lighting that produces virtually none. We moved indoors. We reduced our time in direct sunlight. Roughly 40 percent of natural sunlight is near infrared. Our cells evolved over millions of years in constant exposure to it.
Near infrared sauna therapy isn't some exotic biohack. It's a deliberate effort to restore a frequency of light that we've accidentally engineered out of modern life. That reframing changes the entire conversation. You're not adding something unusual to your protocol. You're replacing something that used to be ordinary.