heat · therapies · education ·
Infrared Or Traditional Sauna? The Famous Finnish Numbers Belong To Only One Of Them
Every article quoting the Finnish mortality data is quoting a study of traditional saunas. The infrared evidence is real, much smaller, and about something else entirely.
Almost every article arguing for infrared saunas quotes the Finnish mortality data.
That data is not about infrared saunas.
The thing most articles get wrong
The studies everyone cites, the ones finding fewer cardiac deaths and less dementia among frequent users, were conducted in Eastern Finland in the 1980s, on men using traditional Finnish saunas: dry air heat, typically 80 to 100 degrees Celsius, wood-fired or electric (Laukkanen et al., JAMA Internal Medicine, 2015).
The infrared cabin sold for a spare bedroom is a different device. It heats your body directly with radiant energy rather than heating the air, which is why it works at a much lower air temperature.
Both raise core temperature. They are not therefore the same intervention with the same evidence, any more than 1.3 and 2 atmospheres are the same hyperbaric dose.
If somebody sells you an infrared cabin using the Finnish numbers, they are quoting a study of a different product.
What infrared actually has behind it
This is the part that surprised us, and it is the reason this article is not a hit piece.
A systematic review searched for controlled studies of sauna bathing in heart failure, looking for both Finnish and infrared studies. Out of 1,444 papers, nine met the inclusion criteria and seven were pooled (Källström et al., Clinical Cardiology, 2018).
Only the infrared studies met inclusion. Not one Finnish sauna trial qualified.
The protocol in those studies: 60 degrees Celsius for 15 minutes, followed by 30 minutes of rest in a warm environment, five times a week for two to four weeks.
The pooled results found significant improvement in:
- B-type natriuretic peptide, a marker that rises when the heart is under strain
- Cardiothoracic ratio, essentially how enlarged the heart appears
- Left ventricular ejection fraction, how well the heart empties
And no significant effect on left ventricular end-diastolic diameter, left atrial diameter, or systolic and diastolic blood pressure.
So the situation is almost the reverse of what the marketing implies. Traditional sauna has the long population data. Infrared has the controlled trials, in a specific patient group, on cardiac markers.
How good is the infrared evidence
The reviewers graded it themselves: from moderate to insufficient, and they called for more evidence on long-term effects.
That is seven pooled studies in heart failure patients over two to four weeks, against 2,315 men followed for twenty years. Different kind of evidence, different kind of claim.
Infrared sauna bath was associated with short-term improvement in cardiac function. More evidence is needed about long-term effects, and the effects of a Finnish sauna on cardiovascular health among patients with heart failure or other cardiovascular diseases.
Källström et al., Clinical Cardiology, 2018
Read that last clause carefully. Even the Finnish sauna, with all its cohort data, has not been trialled properly in heart patients. Both lanes have holes.
A fair comparison
| Traditional Finnish | Infrared | |
|---|---|---|
| Typical temperature | 80 to 100°C air | 60°C in the pooled studies |
| How it heats you | Heats the air, which heats you | Radiant energy heats you directly |
| Strongest evidence | Two-decade cohorts, 2,315 men, mortality outcomes | Pooled controlled studies, heart failure, cardiac markers |
| Weakness of that evidence | Observational, cannot prove cause | Small, short, one patient group, graded moderate to insufficient |
| What it does not have | Randomised mortality trials | Long-term outcome data of any kind |
Neither column is the loser. They are answering different questions, and anyone telling you one is simply better is skipping the part where you ask what for.
The practical differences nobody publishes
Infrared runs cooler, which matters if heat is hard for you to tolerate, and it generally uses less power and needs less space. Traditional sauna gets hot enough that the sessions are shorter and the cooling afterwards is part of the ritual.
None of that is in the literature. It is why the choice is usually made on access and tolerance rather than on evidence, and we think that is a defensible way to choose.
What we are and are not saying
| Claim | Our line |
|---|---|
| Infrared saunas carry the Finnish mortality data | No, and this is the common error |
| Infrared has no evidence | Also no. It has pooled controlled studies in heart failure |
| Infrared improved cardiac markers in those studies | Yes, with the moderate-to-insufficient grading attached |
| Either one treats heart failure | Never, not as a THS promise |
| One is definitively better | No. They have different evidence for different things |
Where the design shows up
The body does not have an infrared receptor and a separate hot-air receptor. It has a core temperature, and a set of responses that fire when that temperature rises.
Two different machines, two different routes, one destination. Which is worth remembering the next time somebody insists their delivery method is the only one that counts.
“There are varieties of workings, but the same God who works all things in all persons.” 1 Corinthians 12:6, NASB
The verse carries the conviction. Nine studies and 2,315 men carry two different kinds of number.
What to do this week
Choose on access and tolerance, not on somebody else’s data.
The heat you will actually use four times a week beats the heat you will use twice a month, and the frequency signal in the Finnish data was stronger than the duration signal.
And if a seller quotes the Finnish mortality numbers at you for an infrared cabin, ask them which sauna the study used. The answer tells you what kind of company you are dealing with.
Read this next: the cohort those famous numbers actually come from: men who used a sauna 4 to 7 times a week had 63% fewer sudden cardiac deaths. And for the trial where fitness outperformed the therapy, what a hot bath does, and why fitness beat both.
Sources
- Källström M, Soveri I, Oldgren J, et al. “Effects of sauna bath on heart failure: A systematic review and meta-analysis.” Clinical Cardiology, 2018;41(11):1491-1501. https://pubmed.ncbi.nlm.nih.gov/30239008/
- Laukkanen T, Khan H, Zaccardi F, Laukkanen JA. “Association between sauna bathing and fatal cardiovascular and all-cause mortality events.” JAMA Internal Medicine, 2015;175(4):542-548. https://pubmed.ncbi.nlm.nih.gov/25705824/
- Laukkanen T, Kunutsor SK, Khan H, Willeit P, Zaccardi F, Laukkanen JA. “Sauna bathing is associated with reduced cardiovascular mortality and improves risk prediction in men and women: a prospective cohort study.” BMC Medicine, 2018;16(1):219. https://pubmed.ncbi.nlm.nih.gov/30486813/
Article metadata retrieved from PubMed. Photograph from Pexels. Scripture quoted from the New American Standard Bible.
Educational content from True Health Solutions. We do not diagnose or prescribe, and nothing here is a substitute for care from someone who knows your history. The body heals. We write about what supports that design.
Questions people ask
- Is infrared or traditional sauna better?
- They have different evidence behind them, which is a more useful answer than better. The long Finnish mortality cohorts studied traditional sauna. The infrared evidence is a smaller body of work in heart failure patients, and it measured cardiac function rather than deaths.
- What temperature is each one?
- Traditional Finnish sauna is dry heat typically 80 to 100 degrees Celsius. The infrared studies that reached meta-analysis used 60 degrees for 15 minutes. Infrared heats you directly rather than heating the air around you, which is why a lower air temperature still raises core temperature.
- What does the infrared evidence actually show?
- In a meta-analysis where only infrared studies met the inclusion criteria, infrared sauna in heart failure patients was associated with reduced B-type natriuretic peptide, reduced cardiothoracic ratio and improved left ventricular ejection fraction. It showed no significant effect on systolic or diastolic blood pressure.
- How strong is that evidence?
- The reviewers rated the strength as varying from moderate to insufficient, and called for more work on long-term effects. Nine studies met inclusion, seven were pooled. That is a fraction of the 2,315 men followed for twenty years in the traditional sauna cohorts.
- So which should I buy?
- If you want the outcomes the Finnish cohorts describe, the honest answer is that those cohorts studied traditional saunas. If access, cost, space or heat tolerance make infrared the one you will actually use, the evidence for it is real but narrower. A cabin you use beats a cabin you do not.
