Short read
Szafraniec, Poręba and Domaradzki at Wrocław University of Health and Sport Sciences published this in Scientific Reports in 2025. Twenty-eight healthy women with normal blood pressure, average age 22.3, none of them with any sauna experience, went through a single session.
The session is the reason to cite it. Three sauna bouts of 10 minutes each at 90 degrees, humidity between 6 and 10 percent, with the first 2 minutes on the lowest bench and the remaining 8 on the middle one. Between and after the bouts, a cooling break of 10 minutes: 6 minutes seated in a 20 degree room, a cold shower at 15 degrees to rinse off, then 2 minutes immersed to the neck in a pool at 15 degrees.
Blood pressure and heart rate were taken straight out of the cabin and in the last minute of each break. Systolic pressure was above baseline in the first bout and showed a falling trend across the three; diastolic pressure was below baseline; heart rate was above baseline in all three and stayed stable across cycles. The authors read the falling systolic trend as an adapting circulatory response within the session.
What it is not: 28 people, one visit, no control group, only young healthy women new to the sauna. The authors call their own work preliminary and ask for longitudinal studies in other age and sex groups. A trend across three bouts in one afternoon is not evidence of lasting blood pressure reduction.