First mentioned in written form in 1112, the Finnish sauna has thought to have been around for more than 2000 years. The Finnish word translates as bath or bath house into English. Originally thought to have been crafted by nomadic Finnish tribes by scraping away some ground, then building a rudimentary tent out of sticks and animal hides. A fire was lit inside to heat rocks and water applied to create steam that cleanses and purifies. As society became more permanent and fixed in a regular location, the sauna evolved into more permanent structures. Regular sauna users were expected to show decorum and respect to their fellow users and conduct themselves as they would in a church setting. Nudity was and is still is part of the bathing experience, so poor behaviour in public sauna that would disrupt this spiritual sanctity would not be acceptable.
Such was the belief of cleansing and purifying, that children were born inside sauna, crops were dried, meats smoked and illness banished. An old Finnish phrase “the sauna is the poor mans pharmacy’ was born.
In the early twentieth century, smoky saunas were becoming a thing of the past, as iron stoves were developed and smoke was removed by chimney. By the mid century, the next evolution of the sauna arrived with electric heaters.
Over hundred of years Finnish and northern European peoples enjoyed the benefits of the sauna, with the heat and the steam somehow improving their health and well being, however, this has only ever been researched and proven until much more recently.
Studies from the Universities of Bristol and Eastern Finland tracked the health of 2300 and 1621 middle aged men over several decades. Those that regularly used sauna had fewer deaths from heart attack or stroke and noted other effects on blood pressure, tension headache and breathing issues. https://theconversation.com/why-saunas-really-are-good-for-your-health-87055