In order to understand the effect of the infrared sauna on your body you have to know how your body reacts to extreme heat. The normal temperature of a healthy person’s body is around 37°C (98.6 ºF). The human body permanently attempts to keep the temperature around this value through the process called thermoregulation. You should also know that if two objects of different temperatures are placed in contact, the heat is transferred from the warmer to the colder one. The same way the body can cool down by transferring heat to the surrounding environment if the environment has a lower temperature than the body. The higher the temperature difference between the body and the environment, the faster the heat transfer will be.
Knowing this you can understand how your body is cooling itself. It also becomes obvious that the closer the air temperature gets to the body temperature the harder it is for the body to cool passively. Therefore this passive way of the body to lose heat is less efficient.
What happens if the temperature of the air surrounding the body is higher than normal body temperature? In this case, the body is no longer able to lose heat passively at all and, in fact, it gains heat from the air, so the body would become warmer. This is why there is also an active way of losing heat and that is sweating. By sweating the body lowers its temperature. It can also control how much heat to lose by adjusting the intensity of the sweating process. All of these happen for a reason: the body needs to keep its normal temperature constant to function properly.
If you are wondering how is possible for sweat to cool the body, there is a very simple physical explanation for that. First of all your skin has a huge number of sweat glands and pores to let the sweat out, so when you sweat your entire skin becomes wet. Secondly, the water on your skin begins to evaporate, and when that happens it absorbs heat from your skin, cooling it down. You can perform a very simple experiment on your own to prove that. All you need to do is make sure your left palm is wet while your right palm is dry, and then just place your palms before your mouth and blow with force. You will feel immediately how your wet palm will feel much colder than the dry one.
The next naturally arising question is: what happens to the body temperature while using an infrared sauna? There has been an experiment done which answers that question. It was performed in 2007 by the Royal institution of Great Britain in their popular Christmas Lectures series. They wanted to show what the effects of extreme heat on the human body are, and how efficient the body is at regulating its temperature. To perform the experiment they required an infrared sauna and they chose Di Vapor to provide it. In turn, Di Vapor donated an infrared sauna to help in this scientific quest.
A human subject was needed for the experiment, so a volunteer was used as a subject. They wanted to measure the exact internal temperature of the subject and for that purpose a very small radio thermometer capsule was used. The volunteer had to swallow it and due to its radio transmitter, the thermometer delivered the temperature results in real time to a radio receiver connected to a computer. This way the computer could display the inner temperature of the subject’s body.
One of the goals was to replicate the conditions similar to some of the hottest places on Earth like the Libyan Desert or the Death Valley, where in the past temperatures were very close or even reached the value of 58 degrees Celsius (136.4°F). A regular stove sauna was considered inadequate to simulate the same natural conditions, so an infrared sauna was used because it can better simulate some of the sun radiation. The infrared radiation doesn’t just heat the surface of the skin, instead it passes through the outer tissue.
Before entering the sauna, the volunteer had an internal body temperature of 37.3 °C (99.14 ºF). After the infrared sauna was heated to 58 °C (136.4°F) the subject entered the sauna with his clothes on. He remained inside for ten minutes and when he came out his temperature was 37.7 °C (99.86 ºF) so his internal body temperatures was only one third of a Celsius degree higher than his initial temperature.
The experiment demonstrated the human body’s natural capacity to efficiently regulate temperature through sweating in order to preserve the vital functions and adjust its metabolism to maintain the temperature close to the 37 °C value.
However, in order to sweat efficiently and regulate its temperature the body needs water. While the body can lose through sweat somewhere between one and two litres of water in just one hour it can only absorb through its intestines a maximum of 1.5 litres in the same amount of time. To prevent dehydration it is important to drink enough water before and during taking a sauna. This will help you stay hydrated and take full advantage of the health benefits that come with the use of an infrared sauna.