University of Eastern Finland study links sauna use to immune response

Researchers from the University of Eastern Finland have discovered that a single 30-minute sauna session can trigger a significant increase in white blood cells within the bloodstream. The study, published in the journal Temperature, suggests that sauna use may temporarily mobilize immune cells from tissues into circulation, allowing them to more effectively patrol the body for pathogens.

The research, which involved 51 adults with a median age of 50, observed increases in all types of circulating leukocytes, including neutrophils and lymphocytes. These cells are critical for identifying and combating infections, such as bacteria and viruses. The study also noted that a short cold shower taken midway through the session may contribute to these effects.

According to Ilkka Heinonen, a researcher at the University of Turku, this process facilitates immune surveillance. However, the effect is transient; levels of neutrophils and lymphocytes typically return to baseline within 30 minutes of completing the session. The researchers also observed minor shifts in cytokine levels, which assist immune cells in communication, varying according to the degree of body temperature increase.