The science behind saunas

Sauna research is promising but mostly observational: it shows that regular sauna users tend to be healthier, which isn't quite the same as proving the sauna caused it. Here's what's known, and how confident to be.

Heart health and longevity

The best-known evidence comes from the Kuopio Ischaemic Heart Disease study in eastern Finland, which followed more than 2,000 middle-aged men for about 20 years. In a 2015 paper in JAMA Internal Medicine, men who used a sauna 4-7 times a week had markedly lower rates of fatal heart disease and death from any cause than men who went once a week. Longer sessions (over 19 minutes) were linked to lower risk too.

The same research group later reported associations between frequent sauna use and lower rates of high blood pressure, dementia and stroke. These are strong, consistent findings, but they come from Finnish men using traditional saunas. People who sauna often may also be healthier in other ways, and the results may not translate exactly to infrared saunas or other groups.

What heat does in the short term

A sauna session raises your heart rate and widens blood vessels, a bit like light exercise. Studies have found short-term drops in blood pressure and improved blood vessel function after a session. Heat also triggers the body to make heat shock proteins, which help protect cells from stress; researchers are still working out how much that matters for long-term health.

Recovery, sleep and mood

Many athletes use saunas for recovery and relaxation, and people commonly report better sleep. The evidence here is smaller and mixed: helpful for comfort and relaxation, less clear for measurable performance gains.

Infrared specifically

There's less research on infrared saunas than traditional ones. Small studies suggest benefits for some people with heart failure, chronic pain and high blood pressure, but they're too small to draw firm conclusions. Claims that infrared saunas "detox" the body go well beyond the evidence: your liver and kidneys handle that, and sweat contains only trace amounts of toxins.

Safety

• Drink water before and after; you can lose a lot of fluid in a session.
• Start with 5-10 minutes and build up. Most people stop at 15-20.
• Don't drink alcohol before or during a session; it's a known risk factor for sauna-related deaths.
• Get out if you feel dizzy, nauseous or unwell.
• Check with your doctor first if you're pregnant, have heart disease, low or uncontrolled blood pressure, or take medication that affects heart rate or sweating.
• Supervise children closely, and keep sessions short and cooler for them.

This page is general education, not medical advice.