As explained above, the brain gives the starting whistle for the body to start making adjustments to the heat of the sauna. One of the big changes in the body that happens in the sauna is that the endocrine system begins to produce a type of protein called a heat shock protein. Heat shock proteins aren’t actually created with the first intention of aiding the immune system but rather with keeping the body cool, as the name would imply! Heat shock proteins have a unique chemical makeup that helps them cool down the parts of the body that they rest near. So, when the body thinks there is a chance it could overheat (like when you spend time in the sauna), it begins to produce these proteins.

Especially when the body starts to get sweaty, the production of heat shock proteins really kicks up. But just as well, by the time that the body is sweaty, this is likely the marker that your sauna session is maybe half over if not more. When you eventually leave the sauna, the body will still have several unspent heat shock proteins that can’t serve their primary function now that the temperature outside the body has returned to normal. There, however, aren’t many things in the world more efficient than the human body and this remains true in the way that it deals with unspent heat shock proteins! After the body is at normal temperature, heat shock proteins are naturally attracted to the body’s immune system and actually reinforce its strength.

While the effect of heat shock proteins on the immune system will likely be minimal at first, it is more than possible to make a real difference in your immune health if you make sauna use a genuine habit. And even better, every time you engage your body enough to make the proteins, your body becomes more efficient in producing them in the future.

The moment your body steps into a hot sauna, your nervous system immediately sends an alert to the brain telling it exactly that. Once the brain thinks that the body has a chance of overheating, several key actions happen in the body. We’ll get into each of those key actions later in this section, as several have specific health benefits of their own. But the fuel that makes all of these quick changes in the body possible is a change in heart rate that happens at the same time. The brain gives the heart and the circulatory system the green light to increase the pump rate of the heart in a healthy way that will help aid quicker acclimation to the temperature change.

While this change in heart rate isn’t as serious as the changes you would see in something like sustained aerobic exercise, it is still serious enough to make a real change in your heart health if regularly taken on.