this reduction is more pronounced when sauna bathing is combined with exercise, compared with either of these practices alone. Tentative evidence supports that the heat stress from saunas can reduce blood pressure and arterial stiffness, and therefore also decrease the risk of cardiovascular disease. These benefits are more pronounced in persons with low cardiovascular function. Evidence exists for the benefit of sauna on people with heart failure. Frequent sauna usage (4-7 times per week) is associated with a decreased risk of neurovascular diseases, including Alzheimer's disease and stroke. Individuals suffering from musculoskeletal disorders could have symptomatic improvement from sauna, and it could be beneficial for glaucoma. It can also relieve the symptoms of respiratory illness and reduce its risk. Weight loss in obese people and improvement of appetite loss present with normal body weight is achieveable with sauna bathing. Evidence for the use of sauna for depression or skin disorders is insufficient, but the frequency of sauna sessions is correlated with a diminished risk of developing psychosis, and it might be beneficial for psoriasis. Sauna bathing coupled with alcohol consumption or dehydration increases the risk of sudden death; the use of narcotic drugs, such as cocaine, also increases the risk. Being severely obese, having high blood pressure, or being diabetic all serve as reasons to decrease the duration of sauna sessions. Individuals prone to postural hypotension or severe valvular heart disease should use sauna cautiously to reduce the risk of a drop in blood pressure. In people with cardiovascular disease, sauna usage is generally safe, as long as their condition is stable. However, sauna bathing is contraindicated in persons with unstable angina and severe aortic stenosis. A one-year study in Finland showed that only 67 (2.6%) of sudden deaths in saunas were non-accidental, mostly due to coronary heart disease. Pregnant women can use saunas as long as their core temperature does not exceed , as this may be teratogenic. Genital heat stress from frequent sauna sessions could cause male infertility. Technologies Today there are a wide variety of sauna options. Heat sources include wood, electricity, gas and other more unconventional methods such as solar power. There are wet saunas, dry saunas, infrared saunas, smoke saunas, and steam saunas. There are two main types of stoves: continuous heating and heat storage type. Continuously heating stoves have a small heat capacity and can be heated up on a fast on-demand basis, whereas