The longevity research was done in traditional Finnish saunas, where the average temperature was 78.9°C. At Longevity Benchmark, we interpret health claims in the context they were measured in. Infrared saunas are 30 to 50°C cooler, so the mortality findings can't simply be applied to them.
The Verdict
Infrared Sauna vs Traditional Sauna on Temperature and Heat Transfer
The three heat rooms differ in air temperature, in humidity, and in how energy crosses into your skin, and each of those changes the dose you receive. A traditional Finnish sauna heats the air and the stones, and you take heat from both. An infrared cabin barely heats the air at all.
Clearlight publishes an operating range of 110 to 140 degrees Fahrenheit for its infrared cabins, which is about 43 to 60 degrees Celsius. Far-infrared emitters radiate at roughly 6 to 12 microns, water in the outer skin absorbs that, and conduction then spreads the energy roughly 2 to 4 centimetres inward. Marketing copy about infrared penetrating deep into the body is describing that spread rather than light travelling through you.
A steam room inverts the problem. It runs cooler than either sauna, and saturated air removes evaporative cooling completely. A steam room at 45 degrees can therefore feel harder than a dry sauna at 85. Geyser Steam Room puts the normal setting at 110 to 120 degrees Fahrenheit, about 43 to 49 Celsius, at 100% relative humidity.
| Criterion | Traditional Finnish sauna | Infrared cabin | Steam room |
|---|---|---|---|
| Air temperature and humidity | 80 C to 100 C at 10% to 20% relative humidity, with a burst of steam whenever water hits the rocks | Roughly 43 C to 60 C, dry, with no water added at any point | Roughly 43 C to 49 C at close to 100% relative humidity |
| How the heat reaches you | Hot air and radiant heat off the stove warm the skin, and blood carries that heat inward | Emitters around 6 to 12 microns are absorbed by water in the outer skin, and conduction spreads the energy about 2 to 4 cm further in | Steam condenses on your skin and releases its heat there, and the saturated air stops sweat evaporating |
| Cardiovascular load in one session | The largest of the three. Skin blood flow climbs and cardiac output rises mainly through heart rate | Smaller at the same session length, because the air sits 30 to 50 degrees cooler | High for the air temperature, since blocked evaporation removes your main cooling route |
| Evidence attached to it | A 2,315-man Finnish cohort followed for a median 20.7 years, plus randomised vascular trials | 25 of the 40 studies in the 2018 systematic review, mostly small, with 16 of 19 cardiovascular ones from a single Japanese group | The thinnest of the three. No mortality cohort has ever been run on steam rooms |
| Power, warm-up and space | 240 V hardwired circuit sized to the heater, 45 to 60 minutes to preheat, and a purpose-built room | Several models run on a 120 V 20 A socket and preheat in about 15 minutes, so a corner of a spare room works | A plumbed steam generator plus a sealed, tiled, sloped enclosure. Rarely practical at home |
| Verdict | The default choice when you own the property and can tolerate the heat | The right call in a rental, and a genuinely smaller stimulus for the same clock time | Choose it for comfort or blocked sinuses. No outcome data covers it |
Core Temperature and Heart Rate Are the Mechanism
The plausible reason regular sauna users died less often is repeated core temperature rise and the circulatory work of shedding it. The Kuopio Ischaemic Heart Disease Risk Factor Study, published in JAMA Internal Medicine in 2015, laid out the sequence. Skin blood flow rises, blood flow to the internal organs falls, and cardiac output goes up mainly through an increase in heart rate.
Air temperature sets the size of that response, and an infrared cabin changes exactly that. A 2015 study in SpringerPlus put trained men through far-infrared and traditional sauna sessions at matched air temperatures of 35 to 50 degrees, varying only the humidity. Heart rate after the far-infrared session came in at 71 beats per minute against 92 after the traditional one.
Both arms ran far cooler than a real Finnish sauna, so the gap in normal use is wider still. Twenty minutes at 55 degrees is not twenty minutes at 85. Calling both a sauna session hides the difference the research was measuring.
Infrared Sauna vs Traditional Sauna on Evidence Quality
Traditional sauna has the population data and infrared has most of the clinical trials, and neither set answers the other's question. In the Finnish cohort, 2,315 men aged 42 to 60 were followed for a median 20.7 years. Compare 4 to 7 sessions a week against 1. The hazard ratio for sudden cardiac death was 0.37, for fatal coronary heart disease 0.52, for fatal cardiovascular disease 0.50, and for all-cause mortality 0.60.
Those are observational numbers, from men only, with self-reported sauna frequency, in a country where sauna is ordinary. People too unwell to sit in a hot room also sauna less, which pushes the association in the direction it went. The study's own authors then added the caveat that decides this comparison.
Their results, at a mean temperature of 79 degrees, cannot be directly applied to steam rooms, hot tubs, and some other types of sauna. That sentence is in the paper. A cabin running at 43 to 60 degrees is one of those other types, which rules out the transfer most infrared marketing depends on.
Infrared's evidence is wider in scope and much shallower in quality. Hussain and Cohen, in Evidence-Based Complementary and Alternative Medicine, counted 40 clinical studies across 3,855 participants, of which 25 used infrared and 11 used Finnish saunas. Thirteen were randomised, and only three of those were judged at low overall risk of bias. Sixteen of the nineteen cardiovascular studies came from one Japanese research group.
That group's protocol is called Waon therapy, and it deserves naming precisely because it is the best infrared evidence in existence. Patients sit in a far-infrared dry sauna at 60 degrees for 15 minutes, then rest under a blanket for 30. A five-year follow-up in the Journal of Cardiology tracked patients with advanced heart failure. Cardiac events or cardiac death hit 68.7% of the control group against 31.3% of the Waon group.
Why Infrared Wins on Wiring and Warm-Up Time
Infrared's real advantage is electrical, and for renters it settles the question outright. Clearlight lists several models that run on a 120-volt 20-amp circuit, which means an electrician may swap an outlet but nobody opens the panel. Circuit requirements run per model rather than per brand, so read the spec for the exact cabin on Sunlighten's range as well as Clearlight's.
A traditional sauna needs a heater sized to the room volume and a hardwired 240-volt circuit of its own. Harvia's Cilindro PC60 is a 6-kilowatt 240-volt unit. Breaker and wire sizing differ by model, so the heater's own manual and a licensed electrician settle it rather than a rule of thumb.
Warm-up time then decides how often either one gets switched on. Clearlight puts infrared preheat at about 15 minutes and a Finnish room at 45 to 60 minutes. A 15 minute warm-up survives a Tuesday evening. An hour does not.
That matters because the exposure behind the Finnish hazard ratios was 4 to 7 sessions a week. On adherence alone, a cabin you actually switch on five times a week beats a hotter room you fire up on Sundays. It does not inherit the Finnish hazard ratios by matching their frequency, because the frequency and the 79 degree room came as one package and nobody has tested them apart.
Prices move, so check them rather than trust a number in an article. Both categories span a wide range set by cabin size, wood species, heater output, and whether the install needs a builder as well as an electrician. Compare current figures on Clearlight's own store and on Harvia's product range before you budget.
How to Get Sauna Benefits without a Sauna
A hot bath costs nothing to install, and it is the passive heat exposure with the most published human physiology behind it. Brunt and colleagues, in The Journal of Physiology, ran eight weeks of hot water immersion in sedentary young adults, heating them to roughly 39 degrees core temperature. They measured improved flow-mediated dilatation, reduced arterial stiffness, thinner carotid intima-media and lower arterial pressure.
Water moves heat into you far faster than air does. A 40 degree bath will usually raise core temperature more than a 50 degree infrared cabin over the same 25 minutes. Sit with your shoulders under the water, because legs and torso alone leave too much of your blood volume out of the heat.
The tradeoffs are real and manageable. You cannot step off for a minute the way you can off a sauna bench, so build up from 15 minutes rather than opening at 30. Stand up slowly, keep alcohol out of it, and get the exposure cleared first if you are pregnant or have any diagnosed cardiovascular disease.
Red Light and Infrared Heat Are Separate Claims
Heating and photobiomodulation work at different wavelengths through different mechanisms, and a cabin offering both is selling two products in one box. Red light therapy runs at roughly 600 to 700 nanometres and near-infrared at roughly 780 to 850 nanometres. Panels at those wavelengths run at intensities deliberately too low to warm you, and they act on cytochrome c oxidase inside mitochondria.
Far-infrared sauna emitters sit thousands of nanometres higher, where tissue water absorbs them and turns them straight into heat. Michael Hamblin set out what the two share in Photobiomodulation, Photomedicine, and Laser Surgery in 2022. Adding a red light panel does not raise the heat dose, and running the cabin hotter does not raise the light dose.
Judge each on its own evidence and price the add-on as an add-on. No trial has shown the two used together beating either used alone. A red light upgrade earns its money only if you would have bought a red light panel anyway.
When to Choose Each Sauna
Four situations settle this cleanly, and most readers are in one of them.
- You own the property and can wire 240 volts. Buy traditional. It is the only version with outcome data behind it, and the hour of preheat is a scheduling problem rather than a physiological one.
- You rent, or live in a flat. Buy infrared. A plug-in cabin that is warm in 15 minutes gets used four times a week, and steady moderate heat beats an ideal sauna you never install.
- You cannot tolerate hot air on your face. Buy infrared. Sitting at 55 degrees for 30 minutes is a real option for people who last four minutes at 90.
- You want the effect this month rather than this year. Use your own bathtub at 40 degrees, shoulders under, three or four evenings a week.
Who this is not for: anyone buying an infrared cabin because they read the Finnish mortality numbers. That purchase is a bet that a cooler, drier stimulus produces the same adaptation, and the bet has never been tested. If those numbers are the reason you are shopping, join a gym with a real Finnish sauna and use it three times a week instead.
Two groups should not book a session yet. Anyone with unstable angina, a recent heart attack, or severe aortic stenosis needs a clinician's view before sitting in any heat room.
Men actively trying to conceive have a smaller decision to make. Hussain and Cohen cite one study of 10 men in which three months of regular sauna use lowered sperm count, concentration and motility. Every measure returned to pre-sauna levels after six months away from the heat. A few months off is the sensible move.
What would change our answer is a randomised trial of infrared sauna use with hard endpoints, cardiovascular events or death, in a general population. A head-to-head study measuring core temperature rise in infrared and traditional cabins at matched session lengths would do almost as much.
If 55 degrees for 30 minutes raised core temperature as much as 85 degrees for 15, the evidence would transfer. We would then point you to whichever is cheaper to install. Until one of those studies lands, the ranking stays traditional first, hot bath second, infrared third on evidence and first on adherence.
Heat is one input among several, and it competes for the same weekly hours as training that carries far stronger data. Our guides on zone 2 cardio and VO2 max, your maximal rate of oxygen uptake, cover which training returns the most per weekly hour. Heart rate variability (HRV) and longevity covers how to tell whether any of it is landing.
Adding cold is a separate decision, handled in our guides to cold plunge benefits and sauna vs cold plunge. Before you settle infrared sauna vs traditional, book one 15 minute session in a public Finnish sauna and find out whether you can tolerate 85 degrees at all. Then price a 240-volt circuit at your own panel.
Frequently Asked Questions
What are the benefits of an infrared sauna?
Three infrared sauna benefits have trial support behind them. Blood pressure falls during and after a session, trials covering chronic fatigue and rheumatic pain report short-term improvement, and trained people rate their recovery better. The 2018 systematic review by Hussain and Cohen found 25 infrared studies among 40 in total, covering 3,855 participants across all sauna types. Only 3 of its 13 randomised trials were rated at low overall risk of bias. Infrared sauna use has not been shown to reduce cardiovascular death or all-cause mortality, because no cohort has ever followed infrared users long enough to look.
Is a sauna better than a steam room?
For cardiovascular outcomes, yes, on the evidence that exists. Every mortality finding attached to heat bathing comes from traditional Finnish dry sauna. The authors of the Finnish cohort wrote plainly that their results cannot be applied directly to steam rooms. A steam room at the gym is still worth using for a blocked chest and for the pleasure of it. It just feels harsher than its thermostat suggests. At 100% humidity your sweat cannot evaporate and your body loses its main cooling route, so 12 minutes is usually the sensible ceiling.
Is a hot tub as good as a sauna?
A hot tub gets closer to the traditional sauna stimulus than an infrared cabin does, because water moves heat into you far faster than air. Immersion to the shoulders at about 40 C raises core temperature steadily. That is the exposure used in the published heat-therapy trials. The differences that matter are practical ones. A hot tub holds you at a fixed temperature with no easy way to take a minute off, so the load builds without the escape valve a sauna bench gives you.
How do you get sauna benefits without a sauna?
Take a hot bath. Brunt and colleagues, writing in The Journal of Physiology in 2016, ran eight weeks of hot water immersion in sedentary young adults, heating them to roughly 39 C core temperature. They measured improved flow-mediated dilatation, reduced arterial stiffness, thinner carotid intima-media and lower arterial pressure. A domestic bath at around 40 C with your shoulders under the water for 20 to 30 minutes is the same exposure at a gentler dose. Stand up slowly afterwards, keep alcohol out of it, and stop early if you feel light-headed.
What is a dry sauna and what does it do?
A dry sauna is any heat room run at low humidity. In practice that covers traditional Finnish sauna at 80 C to 100 C with 10% to 20% relative humidity, and infrared cabins at 43 C to 60 C with no added moisture. Low humidity lets sweat evaporate, and that evaporation is what makes 90 C air survivable for 15 minutes. Men in the Finnish cohort lost roughly 0.5 kg of sweat in a typical session. The heat drives skin blood flow up and cardiac output with it, and that repeated circulatory work is the most plausible reason regular users died less often.
Are Korean saunas different from Finnish ones?
Korean jjimjilbang bathhouses are a different format rather than a different mechanism. One facility usually holds several rooms at different temperatures, including dry kiln rooms hotter than a Finnish sauna, cooled rooms for recovery between them, and wet bathing areas. The exposure in the hottest kilns sits closer to Finnish sauna than to an infrared cabin, which is the part that matters physiologically. No long-term cohort has ever followed jjimjilbang users. Nobody can put a number on the Korean sauna benefits people report.
Does an infrared sauna help your kidneys?
No trial has shown that infrared sauna use improves kidney function. Searches for infrared sauna kidney benefits usually trace back to far-infrared work on keeping arteriovenous fistulas open in haemodialysis patients, which is a blood-vessel result rather than a renal one. A single 20-minute session temporarily lowers glomerular filtration rate because blood is redirected to the skin, and it returns to baseline within 30 to 60 minutes of cooling. Kunutsor and colleagues examined sauna bathing and chronic kidney disease (CKD) in the European Journal of Clinical Investigation using the same Finnish cohort. If you have CKD, treat heat bathing as something to clear with your nephrologist and to drink around.
Does adding red light to a sauna do anything extra?
It adds a second, separate exposure rather than a stronger heat dose. Red light therapy runs at roughly 600 to 700 nanometres and near-infrared at roughly 780 to 850 nanometres. Panels at those wavelengths run at intensities deliberately too low to warm you, and they act on cytochrome c oxidase inside mitochondria. Far-infrared sauna emitters sit thousands of nanometres higher and are absorbed by tissue water as heat. Judge the panel on the red light evidence and the cabin on the heat evidence, because no trial has shown that sauna benefits with red light added beat either exposure used alone.