Thomas DeLauer's argument is straightforward: when it comes to therapeutic heat exposure, temperature matters more than humidity. The sauna wins because it runs hotter — 160 to 200 degrees Fahrenheit versus the steam room's 100 to 120 — and that gap in temperature is not cosmetic. It's the difference between a stimulus your body truly has to adapt to and one it can largely shrug off.
The steam room feels intense. The humidity tricks your nervous system into perceiving more heat than is actually there. But perception and physiology are not the same thing. Your cells respond to actual temperature, not the sensation of it.
DeLauer references the Finnish population and their sauna culture as a foundation, and this is well-trodden scientific ground. The Finnish longitudinal studies are some of the most robust data we have on any lifestyle intervention. Nearly 1,700 men tracked over decades. Four to seven sauna sessions per week correlated with a 50 percent reduction in cardiovascular mortality and a 66 percent lower risk of Alzheimer's disease. These aren't small signals. They're the kind of numbers that, if they came from a pharmaceutical trial, would be front-page news.
The mechanisms align with everything DeLauer describes — improved blood flow, cardiovascular conditioning, the metabolic bump from elevated core temperature, and the serotonin production that makes you feel genuinely better in the hours after a session. None of this is disputed. The disagreement is really about thresholds: how much heat is enough to trigger meaningful adaptation?
The nuance DeLauer touches on — that you may sweat more in a steam room while getting less physiological benefit — is real, and it's underappreciated. Sweating is often used as a proxy for a productive session. It isn't. Heat shock protein activation, growth hormone release, and the cardiovascular training effect all correlate more closely with core temperature elevation than with sweat volume. High humidity at lower temperatures can produce tremendous sweat without fully triggering those deeper mechanisms.
That said, steam rooms are not without value. Respiratory benefits are real — warm, humid air soothes airways, supports mucosal health, and can be genuinely useful for people with chronic respiratory issues. For that specific application, steam has an edge. It's not that steam is bad. It's that sauna is doing more work at the cellular level.
If you have access to both, use both — but intentionally. Sauna first, 15 to 20 minutes at proper temperature, to trigger the full heat adaptation response. Steam afterward if you enjoy it, as a gentler cool-down or for respiratory benefit. If you only have access to one, the sauna is the clearer choice for longevity and performance outcomes.
The 32 percent increase in endurance output DeLauer cites is worth sitting with. That's not a marginal improvement. That's the kind of adaptation that athletes spend months in the gym chasing. And you get it by sitting still in a hot room, consistently, over time.
Here's what most people miss in the sauna-versus-steam conversation: both modalities ultimately work through the principle of hormesis, but the sauna pushes further into the productive stress zone. Your body's heat shock protein response — those molecular chaperones that clear misfolded proteins and protect against neurodegeneration — requires a genuine thermal challenge to activate meaningfully. A steam room at 110 degrees may not cross that threshold for many people. A sauna at 180 degrees almost certainly does.
The uncomfortable truth is that comfort and adaptation are in tension. The steam room is often preferred precisely because it feels more manageable. But the feeling of manageability is exactly the signal that your biology isn't being pushed hard enough to change. The sauna is a better tool not despite its intensity, but because of it.