A new Finnish study suggests that spending time in a sauna may temporarily move more white blood cells into your bloodstream. These immune cells help the body detect and respond to pathogens and diseases.
Researchers found that a 30-minute sauna session increased the number of all types of circulating white blood cells. Participants took a cold shower in the middle of the session to temporarily cool down.
Levels of neutrophils and lymphocytes, two important parts of the immune system, returned to normal levels within about 30 minutes after completing the sauna.
“This may indicate that sauna bathing mobilizes additional white blood cells from the tissues into the bloodstream, where they are redeposited after the session. This regular release of white blood cells into the bloodstream is beneficial, because once they leave their storage site, they are better able to patrol the body and respond to pathogens,” says Ilka Heinonen, an academic researcher at the University of Turku.
A similar release of white blood cells also occurs during exercise. Having more of these cells circulating may improve the body’s immune surveillance and strengthen its ability to respond to potential threats.
Cytokine changes vary with temperature
The researchers also looked at several cytokines, which are signaling molecules that help regulate immune activity. Overall, sauna bathing produced only small changes in the average levels of cytokines circulating in the blood.
However, individual cytokine responses appear to be partially dependent on how much the participants’ body temperature increased during the sauna session.
“Interestingly, however, the levels of some cytokines changed in relation to the increase in body temperature during sauna bathing. A similar association was not observed between white blood cell counts and changes in body temperature,” says Professor Jari Laukkanen, who led the study at the University of Eastern Finland.
Long-term effects remain unknown
Regular sauna use has been associated with a variety of health benefits. The temporal immune changes observed in this study may help researchers understand some of the biological processes behind those associations.
Still, the researchers cautioned that the experiment only measured the immediate effects of a single sauna session. The results of this study do not establish whether repeated sauna bathing leads to lasting changes in immune function or long-term health.
The study involved 51 adults with an average age of 50 years. The result is temperaturea scientific journal focused on the medical physiology of body temperature regulation.
