How hot? How cold? For how long?
The two questions every session starts with, answered by experience level — with the honest caveat that colder and hotter are not automatically better.
Your experience level
Sauna
150–170°F (65–77°C)
8–12 min per round
Sit on the lower bench. Leave when your heart rate feels like a brisk walk.
Cold plunge
59–60°F (15–16°C)
1–2 min per round
Cold enough to feel hard, warm enough to stay calm. End before shivering takes over.
Weekly targets from the research conversation: ~57 total sauna minutes and ~11 total deliberate-cold minutes, split across 2–4 sessions. Build a full session in the Protocol Builder.
Why these numbers
Cold: the response you're after — the catecholamine surge, the mood lift, the alertness — kicks in well above the temperatures social media celebrates. Water at 59°F feels genuinely hard to a beginner and delivers the response; 39°F just gets you there faster with less margin for error. Progress by feel: when a temperature stops requiring willpower, drop a few degrees or add a minute.
Heat: the Finnish cardiovascular studies that made sauna famous used traditional saunas around 176°F+ with sessions of roughly 19 minutes and up, 4+ days a week. Infrared cabins run 60–80°F cooler — you'll still sweat and relax, but if replicating the studied dose is your goal, see infrared vs traditional.
Time beats temperature. Consistency across the week matters more than any single heroic session. The weekly totals — ~57 heat minutes, ~11 cold minutes — are better targets than chasing extremes on either dial.
Safety: never plunge alone or after alcohol; exit cold water before shivering becomes uncontrollable; clear regular heat/cold exposure with a doctor if you're pregnant or have cardiovascular conditions. Educational content, not medical advice.