What is a sauna?

A sauna is typically a room heated to between 70° to 100° Celsius or 158° to 212° Fahrenheit.

Traditional Finnish saunas usually use dry heat, with a relative humidity that is often between 10 and 20 percent. In other sauna types, the moisture is higher. Turkish-style saunas, for example, involve a greater level of humidity.

A sauna use can raise the skin temperature to roughly 40° Celsius or 104° Fahrenheit.

As the skin temperature rises, heavy sweating also occurs. The heart rate rises as the body attempts to keep cool. It is not uncommon to lose about a pint of sweat while spending a short time in a sauna.

Types of saunas
There are several types of sauna, based on how the room is heated.

These include:

Wood burning: Wood is used to heat the sauna room and sauna rocks. Wood-burning saunas are usually low in humidity and high in temperature.

Electrically heated: Similar to wood-burning saunas, electrically-heated saunas have high temperatures and low humidity. An electrical heater, attached to the floor, heats the sauna room.

Infrared room: Far-infrared saunas (FIRS) are different to wood-burning and electrically-heated saunas. Special lamps use light waves to heat a person's body, not the entire room. Temperatures are typically lower than other saunas, but the person sweats in a similar way. Usually, infrared saunas are about 60° Celsius.

Steam room: These are different from saunas. Instead of dry heat, a steam room involves high humidity and moist heat.

Possible health benefits
Regardless of how a sauna is heated, or the humidity level, the effects on the body are similar.

When a person sits in a sauna, their heart rate increases and blood vessels widen. This increases circulation, in a similar way to low to moderate exercise depending on the duration of sauna use.

Heart rate may increase to 100-150 beats a minute while using a sauna. This may bring some health benefits.

Easing pain
Increased circulation may help reduce muscle soreness, improve joint movement, and ease arthritis pain.

Reducing stress levels
As the heat in a sauna improves circulation, it may also promote relaxation. This can improve feelings of well-being.

Improving cardiovascular health
The reduction in stress levels when using a sauna may be linked to a lower risk of cardiovascular events.

One study, conducted in Finland, followed 2,315 men ages 42 to 60 over the course of 20 years. Findings suggested that people who use a sauna may have a lower risk of dying from cardiovascular disease.

Of the participants in the study, a total of 878 died from cardiovascular disease, coronary artery disease, or sudden cardiac death. Participants were categorized by how often they used a sauna, including once a week, two to three times a week, and four to seven times a week.

After adjusting for cardiovascular risk factors, increased sauna use was linked with a reduced risk of fatal cardiovascular-related diseases.

Participants who used the sauna two to three times a week were 22 percent less likely to experience sudden cardiac death than those who only used it once a week. Those who used a sauna four to seven times a week were 63 percent less likely to experience sudden cardiac death and 50 percent less likely to die from cardiovascular disease than those who only used a sauna once a week.

More research is needed to find out if there is a definite link between sauna use and a decrease in deaths from heart disease.

Sauna use may also be associated with lower blood pressure and enhanced heart function.

While studies may be promising, sauna use should not replace an exercise program to keep the heart healthy. There is more evidence to support the benefits of regular exercise.

Skin problems
A dry sauna dries the skin during use. Some people with psoriasis may findTrusted Source that their symptoms reduce while using a sauna, but those with atopic dermatitis may find that it worsens.

Asthma
People with asthma may find relief from some symptoms as a result of using a sauna. A sauna may help open airways, loosen phlegm, and reduce stress.

Lower risk of Alzheimer's?
In 2016, researchers from Finland published findings of a 20-year study that linked sauna use with a lower risk of dementia and Alzheimer's disease. The study involved 2,315 healthy men aged from 42 to 60 years.

Those who used a sauna 2 to 3 times per week were 22 percent less likely to get dementia and 20 percent less likely to get Alzheimer's than than those who did not use a sauna. Those who used a sauna four to seven times a week were 66 percent less likely to get dementia and 65 percent less likely to get Alzheimer's than those who used a sauna once a week.

Health risks and precautions
Moderate use of a sauna appears to be safe for most people. However, a person with cardiovascular disease should speak to a doctor first.

Blood pressure risks
Switching between the heat of a sauna and cold water in a swimming pool is not advisable, as it can raise blood pressure.

A sauna use may also cause blood pressure to fall, so people with low blood pressure should talk to their doctor to make sure sauna use is safe.

People who have recently had a heart attack should also talk to their doctor first.

Dehydration risk
Dehydration can result from fluid loss while sweating. People with certain conditions, such as kidney disease, may be at a higher risk of dehydration.

The increased temperatures can also lead to dizziness and nausea in some people.

Precautions
To avoid any negative health effects, the following precautions are also advised:

Avoid alcohol: Alcohol increases the riskTrusted Source of dehydration, hypotension, arrhythmia, and sudden death.

A year-long studies of people in Finland who experienced sudden death showed that in 1.8 percent of cases, the person had had a sauna within the last 3 hours, and in 1.7 percent of cases, they had done so in the last 24 hours. Many of these had consumed alcohol.

Limit time spent in a sauna: Do not spend more than 20 minutes at a time in a sauna. First-time users should spend a maximum of 5 to 10 minutes. As they get used to the heat, they can slowly increase the time to about 20 minutes.

Drink plenty of water: Whatever type of sauna a person uses, it is important to replace the fluids lost from sweating. People should drink about two to four glasses of water after using a sauna.

Avoid sauna use if ill: People who are ill should also wait until they recover before using a sauna. Women who are pregnant or those with certain medical conditions, such as low blood pressure, should ask their doctor before sauna use.

Supervise children: Children aged 6 and above are safe to use a sauna, but should be supervised when doing so. They should spend no longer than 15 minutes in there at one time.

Far-infarared saunas: Do they work?
Far-infrared saunas (FIRS) have been recommended for people with mobility problems and health issues that make it difficult for them to be in the high temperatures normally found in a sauna.

A review of studies found that the benefits of FIRS may possibly includeTrusted Source:

improvements in some types of high blood pressure, congestive heart failure, and cardiovascular problems
increase in exercise tolerance
reduction in oxidative stress, chronic pain, and chronic fatigue
Data regarding weight loss and blood glucose levels was inconsistent.

However, the researchers note that the evidence is limited by issues such as small sample size, short duration, and the fact that the same core research group carried out many of the studies.

Health myths
There may be some potential health benefits to spending time in a sauna, but there are also some myths.

False: Sweating removes toxins
One is that sweating can remove toxins from the body. It's true that sweating occurs during sauna use, but there is no scientific research that proves sweating detoxifies the body. Toxins such as alcohol, mercury, and aluminum are mainly removed by the kidneys, liver, and intestines.

False: Sauna use aids weight loss
Another myth about the use of sauna is that it leads to weight loss. It is possible to lose about a pound after using a sauna, but weight loss is due to fluid loss, not fat. The weight will be replaced as soon as a person eats or drinks something.