The Short Version
Multiple peer-reviewed systematic reviews and prospective studies consistently associate regular Finnish sauna use with lower blood pressure and reduced arterial stiffness, supported by plausible biological mechanisms. However, the claim overstates certainty: much of the evidence is observational, at least one randomized controlled trial in coronary artery disease patients found no improvement, and acute post-session effects may not translate to lasting benefits for all populations. The association is well-established, but calling it a proven general improvement goes slightly beyond what the current evidence firmly supports.