# Narration and storyboard draft: Sauna and Cardiovascular Prevention

Authored draft, approximately 60–90 seconds; no rendered video claimed.

Sauna research contains real physiological effects and important observational findings. Frequent sauna users in Finnish cohorts had fewer fatal cardiovascular events. Those were prospective associations, not random assignments, and several papers reuse the same cohort family. Controlled heat studies provide a more detailed picture: exercise plus sauna improved blood pressure and estimated fitness, while a coronary-disease trial achieved heat acclimation without improved vascular markers. Supervised Waon therapy in heart failure has selected functional positives, but its major randomized trial did not meet the primaryBNP contrast. A separate matched five-year Waon cohort reported fewer heart-failure or cardiac-death events, an important clinical signal that retains selection and treatment-setting limits. These outcomes do not automatically establish fewer heart attacks, strokes or cardiovascular deaths. Cold exposure has different tradeoffs: it can help some acute recovery outcomes yet impair some training adaptation. A large cold-shower trial reported fewer missed work days, not fewer overall illness days. Vagus devices also need exact product and indication evidence. A named home auricular device has a genuine sham-controlled AF-burden positive; that does not validate every consumer product. Our HSEF v5.3 assessment keeps these findings separate. The broad sauna event-prevention claim remainsGamma with moderate confidence, pending independent causal hard-outcome evidence.

1. Show the exact claim, grade and confidence.
2. Show selected publication milestones; label experimental systems and clinical endpoints.
3. Contrast the strongest result with its source-specific limitation.
4. End with the boundary experiment and primary-source links.

Use authored schematics; do not depict Consensus meters as causal confidence or reproduce publisher graphics without appropriate permission.