GrowtikaFinnish sauna heat exposure induces stronger immune cell than cytokine responses
https://www.tandfonline.com/doi/full/10.1080/23328940.2026.2645467#abstract
All of these studies are always performed by Finns (or SE / DK / NO + maybe Russia).
I'd love to see this (and other sauna studies) replicated by someone somewhere to the south or hotter climates in general (southern Europe, Africa, hotter parts of Asia and the Americas).
It is hard to study this in a place with less access to saunas.