Going to the sauna is not just about simple relaxation or sweating. According to Finnish research, a single session could give our natural defenses a temporary boost. Researchers observed a rapid increase in the number of immune cells in the blood.
To reach this conclusion, the team followed 51 adults around fifty years old. The effects of a thirty-minute session, including a break under a cold shower, were measured. All types of white blood cells present in the blood increased during this short period. Among them, neutrophils and lymphocytes, two major populations, however returned to their starting level about thirty minutes after the end of the exposure.
Unsplash illustration image
This reaction does not result from the creation of new cells. The study indicates that the heat would rather temporarily move cells already present in the tissues into the bloodstream. According to Ilkka Heinonen, a researcher at the University of Turku, this mobilization presents an interest: the moving immune cells then patrol more actively in the body to identify and counter potential threats.
This rapid response from immune cells resembles what happens during moderate physical activity. It is an adaptation that improves the body's surveillance by increasing the number of cells in circulation. These observations allow for a better understanding of certain biological mechanisms that could be at the origin of the health benefits often attributed to regular sauna practice.
The scientists are keen to specify that their work focuses solely on the immediate consequences of a single session. The long-term impacts on health cannot therefore be deduced from these results. Subsequent work could examine how repeated exposures to heat durably alter the immune response and resistance to infections.