Meta-analysis finds sauna bathing linked to blood pressure drops and heart function gains

Researchers pooled data from 16 peer-reviewed studies to estimate how sauna bathing affects cardiovascular measures both immediately after a session and over two-to-four-week treatment periods. They found consistent associations with lower blood pressure and, over the short term, improvements in several markers of heart function, particularly among people with reduced cardiac capacity.

What the study found

The meta-analysis separated two time horizons. In the acute window—within roughly half an hour of a sauna session—body temperature and heart rate rose meaningfully, while both systolic and diastolic blood pressure fell by roughly five to seven mmHg on average. These immediate shifts reflect the well-documented thermal and circulatory response to heat exposure.

Over repeated sessions spanning two to four weeks, the picture shifted toward structural and functional cardiac markers. Left ventricular ejection fraction—a measure of how efficiently the heart pumps—was associated with an average increase of about three percentage points, with larger gains seen in participants who started with lower baseline values. Six-minute walk distance, a standard gauge of functional exercise capacity, improved by roughly 48 meters on average, and a measure of blood-vessel flexibility called flow-mediated dilation also increased.

Several additional short-term markers moved in a favorable direction: systolic and diastolic blood pressure again declined, a hormone linked to heart-wall stress (brain natriuretic peptide) fell substantially, and several measures of cardiac chamber size decreased. One stress hormone, norepinephrine, showed no significant change across the pooled data.

The authors interpreted these patterns as evidence that thermal intervention may support cardiovascular nursing care, particularly for individuals with diminished heart function. They were careful to frame the findings as associations within a clinical context rather than as proof of a standalone treatment effect.

Limits worth knowing

The meta-analysis drew on only 16 studies, and the underlying populations skewed heavily toward patients with diagnosed heart conditions—most notably heart failure—rather than healthy or general-wellness adults. The two time windows examined (acute and two-to-four weeks) leave longer-term effects unaddressed. Heterogeneity in sauna protocols, session frequency, and participant characteristics across the source studies complicates direct comparison. The review received non-U.S. government research support, which is disclosed but does not specify potential conflicts. Adverse events and safety outcomes were not a focus of the analysis, and no head-to-head comparison with other interventions was performed.

About this entry. The Heartwood Review summarizes published, peer-reviewed research in its own words and links to the original source. It is not medical advice; consult a physician before beginning or changing any thermal or recovery practice. Findings summarized here describe the study cited, not any product sold by Teak & Marble Atelier. Corrections.