Sauna (Finnish sauna)

A Finnish sauna is a dry-heat bath, typically 80–100°C with low humidity, used as a passive heat-stress modality. Acute sessions raise core temperature and produce a cardiovascular response (e.g. increased heart rate and peripheral vasodilation) that overlaps with some aspects of exercise, but is not equivalent to aerobic training. Large Finnish cohort studies, often categorising sessions as 1, 2–3, and 4–7 per week, link frequent use with lower cardiovascular and all-cause mortality, with the lowest risk in the 4–7 group; data are observational and causal effects on longevity are not established.