A sauna is a chamber in which the air is hot and dry, with a relative humidity of less than 30 per cent. Due to heat´s natural tendency to rise, in a sauna the temperature can reach 40 or 60 degrees at floor level and 120 degrees near the ceiling.
When entering the sauna, to avoid shocking the body, it is essential to sit on a low bench; once the body has become accustomed to the temperature, a higher bench can be used if desired. The dry air means that it is easier to bear temperatures that in a damp atmosphere would scald the skin.
In Finland there have been saunas for centuries and there are equivalents in many other cultures, such as the north American native peoples, Russia, Japan, Africa, etc.
Saunas have proven therapeutic benefits, but they also involve a small risk of dehydration and drop in blood pressure. Therefore it is essential to wait between an hour and a half and three hours after eating before taking a sauna. After ten or fifteen minutes, the humidity can be increased by activating a control switch or in the traditional way of splashing water onto basalt stones. This makes the body temperature soar, which is known as heatstroke.
Tradition and science coincide in recommending leaving the sauna to pour cold water over the body and then to go back in. This contributes elasticity and resistance to the circulatory system. In Nordic countries it is customary to go out and walk around in the snow. To recreate these conditions, some resorts and spas have ice chambers or fountains.
The sauna-cold cycle can be repeated once or twice, but never during more than a total of two hours. On leaving the sauna, it is essential to have a cold shower and drink water to replace liquids lost through sweating.
It is also customary to flagellate oneself with birch twigs, which stimulates circulation and leaves a pleasant smell. The water poured over the hot stones also has essential oils of pine or eucalyptus added to it and in Finland they sometimes use beer.
The sauna produces general stimulation, vasodilation, increase in heart and breathing rates, sweating and a sedative effect. It is not suitable for weight loss (the body loses water, not fat), but for treating respiratory tract illnesses (asthma, bronchitis), skin problems (psoriasis), rheumatic, vascular and hypertension problems together with a long list of other complications.