When somebody suffers a heat stroke, they go into circulatory shock. Some even lose consciousness or fall into a coma. A heat stroke is caused by a sharp rise in the temperature inside the brain, which in turn causes the breakdown of some brain functions. Such a rise in temperature may occur if the body’s normal regulatory mechanisms fail – in other words, if a person is unable to sweat or otherwise emit heat for any reason. In the sauna, your skin is able to compensate for the change in temperature by sweating, and isn’t hindered by clothing. Even if you can’t see sweat on your skin, you’re still losing moisture and thus cooling down. In any case, you only subject yourself to the high temperature for a matter of minutes – following which you actively cool down. To make sure you sweat profusely, it’s advisable to drink copiously during the day before using the sauna. Sweating is also a matter of practice; you can train yourself to sweat by not staying in the sauna for too long during the first round, and then increasing the length of time with each succeeding round. Last but not least, sitting in a sauna is not nearly as stressful for your circulatory system as hard manual work in the heat, or exercising hard – nor do your muscles generate so much heat!