Traditional Finnish sauna involves dry heat exposure at 80-100°C for 15-30 minute sessions. Infrared saunas operate at lower temperatures (45-60°C) with different physiologic profile.
Mechanism — Heart rate rises to 120-150 bpm (similar to moderate cardio), peripheral vasodilation increases cardiac output, heat shock proteins increase. Releases endorphins, dynorphin, BDNF. Chronic adaptation: improved cardiovascular reserve, better endothelial function.
Use case — 4x/week, 20-30 minutes at 80-100°C — the dose with the cleanest mortality data (Laukkanen cohorts). Re-hydrate aggressively post-sauna. Stack with cold exposure or solo.
Caveats — Cardiovascular precautions for uncontrolled BP, arrhythmia, recent cardiac event. Alcohol + sauna is a real risk. Pregnancy contraindications. Don't sauna when severely sleep-deprived.