The Finnish have been doing this for 9,000 years. Not because they had access to research papers. Not because a wellness influencer told them to. Because generation after generation, they noticed something: the people who used the sauna regularly just seemed to do better. Live longer. Stay sharper. Carry less chronic disease.
Now science is catching up, and what it's finding is worth paying attention to. The Kuopio Ischemic Heart Disease Risk Factor Study — over 2,000 men, 20 years of follow-up — found that sauna use four to seven times per week is associated with dramatically lower rates of cardiovascular mortality. Not marginally lower. Dramatically. The kind of effect size you'd expect from a pharmaceutical intervention, not a hot room.
The article does a nice job explaining the physiological chain: heat detected by skin proteins, signals sent to the brain, heart rate climbs, blood vessels dilate, you sweat. Your body is working. Not as hard as a sprint, but closer to a moderate aerobic session than it might seem. Plasma volume increases. Vascular flexibility improves. And critically, heat shock proteins go to work — refolding or clearing misfolded proteins before they aggregate into the kind of cellular debris that accumulates with age.
This last point is where the research gets quietly extraordinary. In the knowledge base, a 2023 paper on sauna and neurocognitive disease documents a 65 percent reduced risk of Alzheimer's and 66 percent lower risk of dementia in frequent sauna users. That's almost certainly the same heat shock protein mechanism at play. You're not just protecting your heart. You're protecting your brain. The same 20-minute session is doing work across multiple organ systems simultaneously.
Max Levy is right to flag the limitation here: we haven't established definitive cause and effect. Observational data from a Finnish cohort tells us there's a strong association, but healthy people also tend to do more healthy things. The sauna users in this study may have had other lifestyle advantages that contributed to the outcomes.
That said, the plausibility of the mechanisms is high. We understand exactly how heat affects cardiovascular function, inflammatory markers, and protein homeostasis. The Finnish data isn't standing alone — it's being corroborated by emerging research on intermittent versus continuous heat protocols, on contrast therapy combining heat and cold, on dose-response relationships. The signal is consistent across different methodologies and populations.
Four to seven times per week, 15 to 20 minutes per session, traditional temperatures around 80 to 90 degrees Celsius. That's what the Finnish study was measuring. If you're new to this, start twice a week and let your body adapt before increasing frequency. The adaptation is the point. You want your cardiovascular system to get comfortable with the stress, then respond, then strengthen.
The surprising connection worth naming: this is the same hormetic principle underlying cold exposure, intermittent fasting, and resistance training. Short-term stress, appropriate dose, adequate recovery. The sauna is just another way to apply a controlled stressor and let biology do what it's designed to do. Nine thousand years of Finnish wisdom, confirmed one mechanism at a time.