Sauna Session Boosts White Blood Cells
A small Finnish study found a 30-minute sauna session briefly increased circulating white blood cells in participants.
Updated on Nov. 1, 2026 in Allergies
Researchers in Finland tested a traditional sauna session on 51 middle-aged participants, who sat in dry heat at about 73° Celsius (163° Fahrenheit) for 30 minutes with a cold shower halfway through. Circulating white blood cells increased immediately afterward, though most of the increase had faded within 30 minutes.
Why it matters
The findings offer an early look at how heat exposure may briefly alter immune activity in people. Because the study was small and measured only short-term changes, its implications for long-term health remain uncertain.
The experiment tracked 51 middle-aged participants in a 30-minute sauna at about 73° Celsius (163° Fahrenheit) and compared blood counts taken before and immediately after. Researchers did not measure T cells or natural killer cells, and the longer-term effects of the increase remain unknown.
The players
University of Turku
A public research university in Finland whose researchers led the sauna study, which is among the institution's growing body of work on everyday health factors.
The details
Participants took a traditional Finnish sauna session with a cold shower halfway through, and blood samples showed that neutrophils and lymphocytes rose after the session. Cytokine levels barely shifted on average, and most white blood cell increases had disappeared 30 minutes later, though some monocytes lingered.
Timeline
Immediately after the sauna session, white blood cell counts were elevated in participants.
Thirty minutes after the session, most of the increases had dropped off.
Health Landscape
Finnish sauna research from the University of Turku has previously linked regular sauna bathing to cardiovascular outcomes, and this study extends that line of inquiry toward immune function. The work sits within a broader effort to understand how everyday heat exposure may influence human health at the population level.
For people who already use saunas, the study suggests a short session may briefly raise white blood cell counts, though it does not show whether this helps or harms health. Anyone with immune or heart conditions should consult a doctor before changing their heat-exposure habits.
The takeaway
The study adds a small piece of evidence that heat exposure can briefly shift immune activity, but its short timeframe and limited measurements mean it should be read as a starting point rather than a conclusion. Readers interested in sauna use should watch for larger, longer-term studies before drawing firm health conclusions.
Further reading
Explore more on Allergies to see how immune responses are studied and understood.
