A sauna is a small, enclosed room – usually lined with wooden panels -used by people to experience two main kinds of heat session, the goal of both being to induce sweating and the cleansing of the skin.
The two main types of heat generated in saunas are dry and wet, which are differentiated by the sauna’s humidity level. Dry-heat saunas have very hot temperatures (approaching a blistering 100 degrees Celsius (212 degrees Fahrenheit) and very low humidity levels – controlled by an automated system. Wet-heat saunas, on the other hand, have lower temperatures, but higher humidity levels, acting more like a steam bath.
The heat in both cases can be generated in a variety of ways, however the most common practice is to use a stone fire. These are heating elements covered with large smooth stones that, when heated, can have scented water thrown over them to generate large quantities of vapour. These are popular as the heat generated by the stone fire can be spread out more evenly through the water vapour than through standard air convection.
However, the first recorded evidence of a sauna comes from Ancient Greek historian Herodotus, who describes in Histories how the inhabitants of Scythia in central Eurasia used to throw water and hemp seeds on heated stones to create a hot, intoxicating steam.
Read also Infrared Saunas for Health