During the Reformation in Scandinavia the popularity of saunas expanded to other countries because the European bath houses were being destroyed due to syphilis among other things being endemic.

Finns have used the sauna to live in, eat, address matters of hygiene, and, most importantly, give birth in an almost sterile environment.

[3][4] Unlike many other, more densely populated places in Europe, the availability of wood needed to build and warm the sauna has never been an issue.

[11] They are found on the shores of Finland's numerous lakes, in private apartments, corporate headquarters, at the Parliament House and even at the depth of 1,400 metres (4,600 ft) in Pyhäsalmi Mine.

[14] A Second World War-era Finnish military field manual states that a break of eight hours is all that is required for a battalion to build saunas, warm them and bathe in them.

Its original sense signified 'spirit, breath, soul' and this is still seen in the Uralic languages--for example, the Udmurt lul, the Komi lol, the Mansi läl ('life'), the Khanty lil and the Hungarian lélek.

[16] Occasionally one uses a bunch of leafy, fragrant silver birch called a vasta (vihta in Western Finland) to gently beat oneself.

When the heat begins to feel uncomfortable it is customary to jump into a lake, sea, or a swimming pool, or to have a shower.

Mixed saunas with non-family members are most common with younger adults, and are quite rare for older people or on more formal occasions.

[citation needed] In the sauna it is a faux pas to wear clothing in the hot room, although it is acceptable to sit on a small towel or pefletti, a disposable tissue designed to endure heat and humidity (it can be mandatory in a public sauna, such as at a public swimming pool).

In public saunas, swimsuits are banned from the hot room for health reasons: in many indoor swimming pools, chlorine is added to the water for hygiene reasons; if swimwear used in such water is brought to the hot room, the chlorine will vaporize and cause breathing problems for people with asthma or allergies.

[citation needed] In private homes or summer residences, the sauna is usually warmed to honor the guest and refusal may be more difficult.

[21] However, due to the amount of effort and time required to operate them – heating can take most of a day – they are not likely to replace most regular saunas.

The important thing is to have a good löyly, that is when the stones are hot enough to evaporate the water thrown on them into steam that rises to the bathers.

The bather in every type of sauna sits on a high bench near the ceiling where the hot steam reaches them quickly.

Electric saunas usually do have kiuas stones piled over or around the heating element to allow löyly thrown onto them; either as an open, air circulating set-up or as a closed and insulated heat-storing one.

The controls can be wireless and can offer additional settings for sauna lighting, ventilation and steam generating devices.