A sauna is a small, insulated room designed to expose the user to controlled heat for relaxation and wellness. This practice originated in Finland, where it has served as a place for cleansing and social gathering for thousands of years. Modern saunas continue this tradition, using elevated temperatures to promote sweating and support various health benefits.
Traditional Convective Saunas
Traditional saunas operate by heating the surrounding air, which then transfers heat to the user’s body via convection. These rooms are characterized by very high ambient air temperatures, typically ranging from 150°F up to 195°F. The heat source warms a large mass of rocks, which radiate energy and raise the temperature of the entire enclosure. This method creates a predominantly dry heat environment where humidity levels are generally quite low.
One common subtype uses a wood-burning stove to heat the sauna rocks. Wood-burning saunas often achieve the highest temperatures and offer a rustic, intense heat experience. The combustion process requires adequate ventilation, which contributes to the characteristic dryness of the air. This method requires manual labor for stoking and precise control over the fire.
Electric saunas represent the most common modern installation, especially in commercial gyms and homes. An electric heating element warms the rock pile, allowing for easier temperature regulation via a simple control panel. This convenience makes the electric heater a practical choice for consistent and reliable heat sessions.
Users often introduce a brief burst of steam, known as löyly, by carefully ladling water onto the hot stones. This action temporarily increases the perceived heat and humidity level within the sauna space. Because the ambient air temperature is so high, this added moisture quickly dissipates, maintaining the overall low-humidity profile.
Infrared Radiant Saunas
Infrared saunas employ a fundamentally different method of heat transfer compared to traditional types by using specialized ceramic or carbon panels. These panels emit electromagnetic waves within the infrared spectrum, which are absorbed directly by the body’s surface and underlying tissues. This direct energy transfer, known as radiant heat, causes an increase in core temperature from the inside out without significantly heating the surrounding air.
Since the air is not the primary heating mechanism, the ambient temperature in an infrared sauna remains much lower, typically ranging from 120°F to 140°F. This characteristic makes the experience tolerable for users sensitive to the intense heat of convective rooms. This lower heat profile allows for deeper penetration of heat into the body without the stress of extremely hot air.
Infrared light is categorized into three main segments based on wavelength: Near, Mid, and Far Infrared (FIR). FIR is the most commonly utilized wavelength in commercial and home sauna units, as it is efficiently absorbed by water molecules in the skin and body. This deep absorption promotes the significant sweating response characteristic of this type of sauna. Near and Mid-infrared wavelengths are sometimes included in full-spectrum units but are less dominant than FIR.
The advantage of infrared saunas lies in their ability to achieve a robust sweating response at a lower overall air temperature. Since the energy bypasses the air, users can tolerate longer sessions compared to the high-temperature environment of a traditional sauna. The humidity level in these saunas is extremely low and generally unregulated.
Distinguishing Saunas from Steam Rooms
Saunas and steam rooms are often compared but provide two distinct thermal experiences based on environmental conditions. Saunas, encompassing both convective and infrared types, are universally characterized by low humidity and either extremely high ambient heat or direct radiant heat. This dry environment forces the body to sweat as the primary method of evaporative cooling.
A steam room, in contrast, operates at 100% relative humidity, creating a completely saturated environment. These rooms rely on a dedicated steam generator, not heated rocks or panels, to inject heated vapor. The air temperature is kept much lower, typically ranging from 100°F to 120°F, because the high humidity prevents effective sweat evaporation.