Science of Saunas and What Happens to Your Body

by Wes McMahon February 1, 2024

Saunas have long been praised for their relaxing and rejuvenating qualities, but the science behind them reveals far more profound benefits. If you're a sauna enthusiast or someone curious about the effects of these heat-based therapies, it's worth understanding what happens to your body when exposed to different sauna temperatures.

This guide will delve into how saunas work, the effects of temperature on your body, the scientific and clinical benefits of sauna use, and provide insights from the medical community.

How Saunas Work

Saunas function by exposing your body to high temperatures, generally between 150°F and 195°F (65°C to 90°C), depending on the type. The heat is typically generated through a stove, which could be electric, wood-burning, or infrared, and in traditional saunas, water is sometimes poured over hot rocks to produce steam, adding humidity to the dry heat.

The basic principle of a sauna is thermotherapy, which is the use of heat to induce physiological changes in your body. When you sit in a sauna, your skin temperature increases, and your body responds by trying to cool itself down, primarily through sweating.

Blood vessels dilate (a process known as vasodilation), which increases circulation, and your heart rate goes up as the body tries to maintain a stable core temperature. This process stimulates various systems in your body, offering both immediate and long-term health benefits.

What the Different Temperatures Do to Your Body

The temperature inside a sauna can have varying effects on your body. Here's a breakdown of how different temperature ranges impact your physiology:

Mild Heat (100°F to 130°F / 38°C to 55°C)

Mild sauna temperatures are typically associated with infrared saunas, which penetrate deeper into the skin using radiant heat. In this temperature range, your body will start to warm up, and you may sweat lightly.

While the heat is milder, the body still begins the process of detoxification, and blood circulation improves. It’s a gentle introduction for those new to sauna use or those with medical conditions that limit their heat tolerance.

Moderate Heat (130°F to 150°F / 55°C to 65°C)

At these temperatures, your body starts to experience more noticeable physiological changes. Sweating increases significantly, your cardiovascular system is activated, and your heart rate elevates to a level similar to light exercise.

Blood flow to the skin and extremities increases, improving circulation and promoting relaxation. This is a common range for regular sauna users who want to enjoy moderate detoxification and circulatory benefits without overstressing their system.

High Heat (150°F to 195°F / 65°C to 90°C)

In this high-temperature range, which is typical of traditional Finnish saunas, your body works hard to regulate its core temperature. Sweating becomes profuse, and your heart rate can increase by 50-70%, mimicking the effects of vigorous exercise. The intense heat causes the blood vessels to dilate further, significantly boosting circulation.

Some people report experiencing a euphoric feeling due to the release of endorphins, the body's natural painkillers. However, it is crucial to stay hydrated and avoid prolonged exposure at these temperatures to prevent heat-related issues like dehydration or dizziness.

Clinical and Science-Based Benefits

The health benefits of sauna use are not just anecdotal; they are backed by a growing body of scientific research. Here are some of the key benefits you can expect from regular sauna sessions, based on clinical evidence:

Cardiovascular Health: One of the most well-researched benefits of sauna use is its positive impact on heart health. Studies show that regular sauna sessions can improve cardiovascular function by lowering blood pressure, reducing arterial stiffness, and improving endothelial function. The increased heart rate and improved circulation mimic the effects of moderate exercise, which is why saunas are often recommended for heart health.
Detoxification: Sweating is one of your body's natural ways to detoxify. While your liver and kidneys are the primary organs for detoxification, sweating helps to eliminate toxins like heavy metals and chemicals stored in fat cells. Regular sauna use can support your body's detoxification processes by encouraging a more profound sweat than typical daily activities.
Muscle Recovery and Pain Relief: For those who suffer from chronic pain, joint stiffness, or muscle soreness, saunas can provide significant relief. The heat helps to relax muscles, reduce inflammation, and improve blood flow to the affected areas, which can speed up recovery and reduce pain levels. In fact, research has shown that heat therapy, including saunas, can help people with conditions like arthritis and fibromyalgia manage their symptoms more effectively.
Stress Reduction and Mental Health: Saunas have a calming effect on both the body and mind. The heat helps to relax tense muscles, but it also triggers the release of endorphins, which elevate mood and reduce stress. Some studies have even suggested that regular sauna use can lower levels of cortisol, the body’s primary stress hormone, while increasing serotonin, which helps regulate mood and well-being.
Improved Skin Health: The process of sweating during a sauna session opens up your pores, allowing impurities to be flushed out, which can help improve skin clarity and texture. The increased blood flow to the skin also delivers more oxygen and nutrients, promoting a healthy glow.
Longevity: Perhaps one of the most exciting findings in sauna research comes from long-term studies that show a correlation between regular sauna use and longevity. A Finnish study that followed over 2,000 men for more than 20 years found that those who used saunas frequently (4-7 times per week) had a 40% lower risk of all-cause mortality, compared to those who used saunas less frequently.

Medical & Clinical Studies

Many of the benefits of saunas are backed by medical research and have been featured in reputable journals and studies. For example:

A study published in JAMA Internal Medicine highlights the cardiovascular benefits of sauna use, demonstrating a reduced risk of heart disease and mortality among frequent sauna users.
The Annals of Clinical Research published findings showing that sauna therapy is beneficial for people with musculoskeletal disorders, especially for those with chronic pain conditions like rheumatoid arthritis and osteoarthritis.
Another study in The American Journal of Medicine found that sauna use can help reduce blood pressure, lower the risk of hypertension, and improve overall cardiovascular health.

Conclusion

The science of saunas shows that regular use can significantly benefit your health, from improved cardiovascular function to enhanced mental well-being. By understanding how saunas work and the effects of various temperatures, you can make informed decisions about your sauna routine and reap the many science-backed benefits of heat therapy.

Whether you're looking to detox, reduce stress, or promote longevity, saunas offer a time-tested and scientifically supported way to improve your overall health.