How do saunas work?

Every sauna makes you hot enough to sweat. What differs is what does the heating, and that changes the temperature, the feel and the wiring.

Traditional (Finnish) saunas

An electric or wood-burning heater warms a pile of stones, and the stones heat the air. Hot air rises, cooler air sinks, and that circulation (convection) surrounds you with heat. Rooms typically run 150-195°F with low humidity. Ladle water onto the stones and it flashes into steam, briefly raising the humidity and making the room feel much hotter. The Finns call this löyly.

Infrared saunas

Infrared saunas use panels (emitters) that give off infrared light. Instead of heating the air first, the light warms your skin and the surfaces it hits directly, the way sunshine warms you on a cold day. The air stays cooler, usually 120-150°F, so sessions feel gentler and many people stay in longer.

• Far infrared is the most common type and produces most of the heat you feel.
• Full spectrum saunas add near and mid infrared. Some also add visible red light panels.
• Carbon emitters spread gentle heat over a wide area; ceramic emitters run hotter in smaller spots.

Wood-fired saunas and tents

A wood stove heats stones, just like an electric traditional heater, without needing power. Tents from brands like North Shore and SweatTent can pass 200°F, and need a safe outdoor spot and a supply of firewood.

Sauna blankets

A blanket is a sleeping-bag-shaped wrap lined with infrared heating elements. You lie inside with your head out. It's the cheapest and most compact option, but you can't move around and the experience is very different from sitting in a room.

Saunas vs. steam rooms

A steam room runs much cooler (around 110-120°F) at nearly 100% humidity, so it feels wet and heavy. A sauna is hotter and drier. They're different experiences, and steam rooms need waterproof construction and a steam generator.

What happens in your body

As your skin and core warm up, blood vessels widen, your heart rate rises (often to levels similar to light or moderate exercise) and you start to sweat to cool down. That cardiovascular response is what most of the research on sauna health looks at. Read what the science says.