One Sauna Session Sends Immune Cells Surging, Study Finds
Your next trip to the sauna could be doing more for your health than you think. A new Finnish study, published by the University of Eastern Finland in the journal Temperature, found that just 30 minutes in a sauna—with a brief cold shower midway—temporarily increased the number of white blood cells in participants’ blood. This response may help explain how the body mobilizes immune cells.
Researchers studied 51 adults with an average age of 50, taking blood samples before the sauna session, immediately afterward, and 30 minutes later. They observed a significant increase in every type of circulating white blood cell measured, including:
- Neutrophils, the body’s first responders to infection
- Lymphocytes, which support antibody production and immune memory
Participants’ average body temperature rose from 36.4°C to 38.4°C—roughly the range of a mild fever.
“This kind of periodic release of white blood cells into the bloodstream is beneficial, as once they leave their storage sites, they are better able to patrol the body and respond to pathogens,” said Ilkka Heinonen, Academy Research Fellow at the University of Turku.
The immune response closely resembles the boost seen during physical exercise, offering a possible explanation for some of the health benefits associated with regular sauna use.
Source: ScienceDaily – University of Eastern Finland, October 28, 2026