A single sauna session sends immune cells surging through your body — SkimNews
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- University of Eastern Finland researchers observed an increase in every circulating white blood-cell type they measured after 30 minutes in a sauna with a brief cold shower halfway through.
- Neutrophils and lymphocytes entered the bloodstream in greater numbers during the session, then returned to their original counts within 30 minutes after it ended.
- Ilkka Heinonen, an Academy Research Fellow at the University of Turku, said the findings suggest sauna bathing mobilizes white blood cells from tissues so they can patrol for pathogens before being redeposited after the session.
- Jari Laukkanen, who led the study, reported that several cytokines changed with the rise in body temperature, although average cytokine levels showed little overall change and white-blood-cell counts had no comparable temperature association.
- The study involved 51 adults with an average age of 50 and examined only the immediate effects of one sauna session, not lasting immune improvements.
- The tested routine combined 30 minutes of sauna heat with a brief cold shower, so the results describe the two together rather than the isolated effect of heat alone; the researchers cautioned that they do not establish reduced illness risk.
- Temperature published the study in 2026 as “Acute Finnish sauna heat exposure induces stronger immune cell than cytokine responses,” in Volume 13, Issue 2, page 186.
Why it matters: For sauna users, the 51-person study offers a physiological clue: the measurable immune-cell increase reversed within 30 minutes after the combined sauna-and-cold-shower session. It does not establish lasting immune improvement, reduced illness risk, or the separate effect of heat alone.
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