Infrared saunas heat your body directly using infrared light rather than heating the air around you. This is the core difference from a traditional sauna, where a heating element warms stones, the stones warm the air, and the hot air eventually warms your body. In an infrared sauna, the light passes into your skin and raises your tissue temperature from the inside out, which is why the room itself feels noticeably cooler, typically between 100°F and 150°F compared to the 150°F to 195°F of a traditional Finnish sauna.
Radiant Heat vs. Convection Heat
A traditional sauna works through convection. A heater warms stones, the stones radiate heat into the enclosed room, and that superheated air transfers energy to your skin. Your body heats up because it’s surrounded by air that’s far hotter than your core temperature. You can think of it like sitting in a hot oven.
An infrared sauna skips the middleman. Panels mounted in the walls emit infrared light, a portion of the electromagnetic spectrum just beyond what your eyes can see. This light travels directly to your body, where your skin and tissues absorb it. The energy converts to heat inside your tissue rather than bouncing off the surface. It’s closer to the way sunlight warms your skin on a cool day: the air temperature might be mild, but you still feel heat where the light hits you.
How Deep Infrared Light Penetrates
Infrared saunas use wavelengths in the infrared spectrum, and the depth they reach depends on whether the unit uses near-infrared, mid-infrared, or far-infrared emitters. Most consumer infrared saunas use far-infrared, which penetrates a few millimeters into the skin. Near-infrared wavelengths go deeper, reaching roughly 1 to 3 centimeters into tissue according to optical penetration data from the Oregon Medical Laser Center. Some saunas advertise “full spectrum” panels that combine all three ranges.
In practical terms, this means far-infrared energy heats mainly your skin and the tissue just beneath it, stimulating blood flow and sweat glands at the surface level. Near-infrared reaches further into muscle and connective tissue. Regardless of the wavelength, the absorbed energy triggers the same cascade: your body registers the warming and responds as if you’re overheating, even though the room around you is relatively cool.
What Happens in Your Body During a Session
Once your tissue temperature starts climbing, your body activates its cooling systems. Blood vessels near the skin dilate to push warm blood toward the surface, your heart rate increases, and your sweat glands kick in. A 2025 study published in the American Journal of Physiology compared far-infrared saunas to traditional saunas and hot water immersion. During far-infrared sessions, heart rate rose by about 26 beats per minute above baseline. Traditional saunas produced a slightly higher increase of around 34 beats per minute, and hot water immersion pushed heart rate up by 39 beats per minute.
Core body temperature tells a similar story. Far-infrared saunas raised core temperature by essentially 0°C in that study, meaning the heat stayed largely at the surface. Traditional saunas raised it by about 0.4°C, and hot water immersion by 1.1°C. This is why infrared saunas feel more tolerable for many people. You still sweat heavily and your cardiovascular system responds with increased blood flow, but the deep thermal stress is gentler than sitting in a room of 180°F air or submerging in hot water.
That cardiovascular response is the mechanism behind much of the interest in sauna use for heart health. The repeated dilation of blood vessels and the mild increase in cardiac output mimic some effects of light exercise. Your body also releases heat shock proteins, which play a role in cellular repair and stress adaptation.
Typical Session Guidelines
If you’re new to infrared saunas, starting at 100°F to 120°F gives your body a chance to adjust without overwhelming your cooling systems. Most people work up to higher temperatures over several sessions. Once you’re acclimated and know what feels comfortable, a 30-minute session every other day is a common protocol. Some experienced users go longer or more frequently, but every-other-day use gives your body recovery time between sessions.
Hydration matters more than you might expect. Because the air doesn’t feel oppressively hot, it’s easy to underestimate how much you’re sweating. Drinking water before, during, and after a session helps replace what you lose.
Who Should Avoid Infrared Saunas
Several medical conditions make infrared sauna use risky. People with conditions that impair sweating, including multiple sclerosis, central nervous system tumors, and diabetic neuropathy, can overheat because their bodies can’t cool down properly. Those with cardiovascular problems like uncontrolled high or low blood pressure, congestive heart failure, or impaired coronary circulation need to be cautious, since the increased heart rate and blood vessel dilation add stress to an already compromised system.
Certain medications also change the equation. Diuretics, beta-blockers, barbiturates, and even common antihistamines can interfere with your body’s natural heat-loss mechanisms, raising the risk of heat stroke. Pregnant women should get medical clearance, as elevated body temperature can cause fetal harm. Alcohol use before or during a session is a particularly bad combination: it impairs judgment, raises heart rate on its own, and compounds the cardiovascular strain of the heat.
If you have metal surgical implants like pins, rods, or artificial joints, those generally reflect far-infrared waves and aren’t directly heated. Silicone implants are different. Silicone absorbs infrared energy and can warm up during a session, so anyone with silicone prostheses should check with their surgeon before using one. Fresh joint injuries should not be heated for at least 48 hours, and any joint that’s chronically hot and swollen may respond poorly to additional heat. Sauna use should also be avoided during a fever or any active enclosed infection.
How the Experience Differs From Traditional Saunas
The most obvious difference is comfort. Walking into an infrared sauna feels like stepping into a warm room, not a blast furnace. There’s no steam, no water poured over rocks, and the air you breathe feels relatively normal. Sweating usually begins 10 to 15 minutes in, building gradually rather than hitting you immediately. Many people find this makes it easier to stay in for a full session, especially those who find the intense heat of a traditional sauna overwhelming or claustrophobic.
The tradeoff is intensity. Traditional saunas produce a stronger core temperature increase and a higher cardiovascular response. For people chasing the deepest possible heat stress, a traditional sauna or hot bath delivers more. For those who want the sweating, the blood flow, and the relaxation at a lower perceived intensity, infrared fills that gap. Both types activate the same basic physiological pathways. They just differ in how aggressively they push your body through them.