Dr. Shang's argument is deceptively simple: the sauna trains your vessels. Heat opens them. Cold closes them. Repeat this three or four times, and you've done something for your cardiovascular system that feels more like therapy than exercise — because it essentially is both.
What I find most interesting isn't the cardiovascular piece itself. It's the offhand comment he makes almost in passing: "If you train the cardiovascular system and the vessel regulation, you get also down to the immune system." He says it like it's obvious. But it's actually a profound statement about biological interconnection — that the same mechanism that lowers your blood pressure is also teaching your immune system to respond better to threat.
The knowledge base has a lot to say here. The 2023 paper on sauna and neurocognitive disease puts numbers on what Dr. Shang gestures toward — 65% reduced risk of Alzheimer's, 66% lower risk of dementia for regular sauna users. These aren't cardiovascular outcomes. They're brain outcomes. And yet the mechanism is the same: improved blood circulation, reduced inflammation, better vascular tone. The body is one system. When you improve the plumbing, everything downstream benefits.
Rhonda Patrick's work, which I've spent a lot of time with, reaches the same conclusion through a different lens. She focuses on heat shock proteins — the molecular janitors that clear misfolded proteins before they accumulate into plaques. Dr. Shang doesn't mention heat shock proteins, but they're part of the same story. Heat stress is a signal. The body reads that signal and responds by cleaning house, shoring up defenses, improving efficiency.
There's genuine consensus on the cardiovascular benefits. The Finnish longitudinal data is robust, replicated, and consistent across multiple research groups. The immune system connection is slightly softer — Dr. Shang describes it as "one of the secrets of the body," which is a graceful way of saying we observe the effect more clearly than we understand the exact mechanism. The disagreement isn't really disagreement — it's a difference in how much certainty different researchers are willing to claim.
Three to four sessions per week is where the data clusters. Twenty to thirty minutes at temperature. The type of sauna matters less than Dr. Shang's broader point suggests — Finnish dry heat, steam room, infrared — the research shows benefits across all formats. Pick the one you'll actually use consistently. Ritual sustained over months is worth more than the perfect protocol used twice.
Dr. Shang mentions that frequent long-term sauna users actually develop lower core body temperatures over time. This is counterintuitive. You'd expect repeated heat exposure to push baseline temperature up. Instead, the body becomes more economical — it learns to regulate with less. It's the same adaptation you see in endurance athletes, who often have lower resting heart rates precisely because their cardiovascular systems have become so efficient. The sauna doesn't just train your vessels for acute response. It teaches your thermoregulatory system to run leaner, quieter, more resilient. That's not a side effect. That's the whole point.