Infrared Saunas: What the Research Actually Says

To get the most out of an infrared wellness suite, it helps to understand what actually happens physiologically when you use one. Unlike a traditional Finnish sauna — which relies on high ambient air temperature (roughly 170–200°F) to heat the body from the outside in — infrared saunas use radiant heat panels that warm the body more directly, at a lower ambient air temperature (typically 120–140°F).

Here's an honest look at how infrared heat interacts with the body, and how to get a comfortable, effective session — written with real sourcing, not marketing shorthand.

1. How Infrared Wavelengths Are Categorized

The infrared spectrum is generally divided into three bands, which differ in how far they penetrate the skin:

Near-Infrared (NIR): The shortest wavelengths, interacting primarily with the outer layers of skin.

Mid-Infrared (MIR): Slightly longer wavelengths that reach somewhat deeper into subcutaneous tissue.

Far-Infrared (FIR): The band most commonly used in infrared sauna heaters. Far-infrared is what drives the heavy sweat response people associate with infrared sauna use, at a lower ambient air temperature than a traditional sauna.

You may see marketing claims that far-infrared "penetrates 3–4 inches into the body." We're not going to repeat that claim here — independent estimates of actual infrared penetration depth into human tissue are much shallower (generally a few millimeters), and we'd rather be accurate than impressive. What far-infrared reliably does is warm the skin and outer tissue directly, which is what drives the elevated heart rate and sweat response during a session.

2. What We Can Actually Point To: The Research on Sauna Use Broadly

Most of the credible long-term research on sauna health outcomes — cardiovascular health, blood pressure, and related benefits — comes from studies on traditional (not infrared) sauna use, most notably a large, long-term Finnish population study. We cover that research, and what it does and doesn't tell us, in detail in our Benefits of Daily Sauna Usage guide. Infrared-specific research is a newer and smaller body of evidence, and results are less established than the traditional sauna findings.

We mention this distinction because it matters: claims about infrared saunas often borrow the strength of the traditional-sauna research without noting that the studies weren't done on infrared devices specifically.

3. Getting the Most Out of Your Session

A few practical guidelines that apply regardless of the underlying mechanism:

Hydration: Because you'll sweat significantly during a session, drink water before and after — the general guidance is to hydrate normally throughout the day rather than requiring a specific pre-session ritual.

Skin Clearance: Avoid thick lotions or oils immediately before a session; heavy topicals can reduce how the infrared panels warm the skin's surface.

Positioning: Sit upright rather than lying down for more even exposure, since heaters are typically positioned along the back, front, and calf walls of the cabin.

A Note on Safety

Infrared sauna use is safe for most healthy adults, but it does raise heart rate and core body temperature and increases fluid loss through sweat. If you are pregnant, have a cardiovascular condition, uncontrolled blood pressure, or take medication affecting heart rate or hydration, talk to your doctor before starting regular use. This article is for general information only and is not medical advice.