Sauna + Cold Shower Boosts Every White Blood Cell Type
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- Finnish researchers found that a 30-minute sauna session paired with a brief cold shower increased every type of white blood cell in participants' bloodstream, including key infection-fighters like neutrophils and lymphocytes.
- Neutrophils and lymphocytes returned to their usual levels within about 30 minutes after the sauna ended, suggesting the immune cells were temporarily mobilized from tissue storage sites and then redeposited.
- Professor Jari Laukkanen led the study at the University of Eastern Finland with 51 adults averaging 50 years old; the findings were published in the journal Temperature (DOI: 10.1080/23328940.2026.2645467).
- Academy Research Fellow Ilkka Heinonen (University of Turku) said the white blood cell release pattern resembles what happens during physical exercise, and that cells leaving their storage sites become better equipped to patrol the body for pathogens.
- Cytokine levels showed only small average changes overall, but individual cytokine responses correlated with how much each participant's body temperature rose during the session — an association not seen between body temperature and white blood cell counts.
- The researchers cautioned that the experiment measured only immediate effects of a single session and cannot establish whether repeated sauna bathing produces lasting immune changes or long-term health benefits.
Why it matters: The 51-participant study is the first to track a full panel of immune cells and cytokines around a single sauna-plus-cold-shower session in real time, giving scientists a concrete mechanistic candidate for the long-observed links between regular Finnish sauna use and reduced disease risk. Because effects reset within 30 minutes and only one session was tested, the data explain a brief mobilization pattern — not durable immunity gains.
