Is Sauna Good for You? What the Research Actually Says

Sauna has become increasingly associated with health, recovery and wellbeing. Some of those claims are well supported. Others have travelled considerably further than the research allows.

So what do we actually know?

The strongest long-term evidence comes from Finland. Two large prospective studies found that people who used a traditional sauna frequently had substantially lower rates of cardiovascular death than those who used one about once a week. The important qualification is that these were observational studies: they show a strong association, but they cannot prove that sauna itself caused the difference.

What makes the research particularly interesting is the pattern behind it. The people showing the strongest associations weren't occasional sauna users. They were using a traditional sauna several times a week, often as a regular part of their routine.

That matters if you're considering buying one. A sauna is only useful if it becomes something you actually use.

What did the Finnish research find?

The best-known study was published in JAMA Internal Medicine in 2015. It followed 2,315 men aged 42 to 60 in eastern Finland for a median of 20.7 years. The participants reported how often and how long they used a sauna, with the average sauna temperature recorded at 78.9°C.

Compared with men who reported one sauna session per week, those using a sauna four to seven times per week had:

The corresponding hazard ratios were 0.37 for sudden cardiac death and 0.60 for all-cause mortality.

Session duration also mattered. Men whose sauna sessions lasted more than 19 minutes had about half the rate of sudden cardiac death compared with those whose sessions lasted less than 11 minutes.

A second study, published in BMC Medicine in 2018, followed 1,688 Finnish adults — 867 women and 821 men — for a median of 15 years. The average sauna temperature was 75.9°C, and there were 181 cardiovascular deaths during follow-up.

In the overall study population, four to seven sauna sessions per week were associated with a hazard ratio of 0.23 for cardiovascular mortality compared with one session per week after adjustment for established risk factors and other potential confounders. More than 45 minutes of sauna use per week was also associated with a lower rate of cardiovascular mortality than 15 minutes or less.

That's a remarkably consistent signal across two long-running cohorts.

But it still isn't proof.

What actually happens to your body in a sauna?

The cardiovascular response to sauna is real and measurable.

During sauna bathing, heart rate rises, blood vessels dilate, skin blood flow increases and sweating causes fluid loss. The 2018 study notes that heart rate can rise to around 120–150 beats per minute during sauna bathing, producing a cardiovascular response comparable in intensity to low- to moderate-intensity physical activity.

The researchers have proposed several possible mechanisms through which repeated heat exposure could influence cardiovascular health, including improved vascular function, reduced arterial stiffness and changes in autonomic nervous-system regulation. These mechanisms help explain why the long-term observational findings are biologically plausible, but they don't turn an association into proof of cause and effect.

In practical terms, a sauna session is doing considerably more than simply making you feel warm.

And that is part of what makes regularity interesting.

How much sauna did the research actually describe?

This is arguably the most useful part of the research if you're thinking about buying a sauna.

The strongest association in the Finnish studies was found among people using a sauna four to seven times per week.

The 2018 study also found an association between greater total sauna time per week and lower cardiovascular mortality. However, the researchers could not establish a particular minimum session length that produces a health benefit.

The important takeaway isn't that everyone should suddenly aim for seven sauna sessions a week.

It's that the research describes a habit, rather than an occasional indulgence.

That changes the buying question.

Instead of asking only:

Which sauna looks best?

it's worth asking:

Which sauna am I actually going to use several times a week?

That makes heating time, comfort, running cost and where the sauna sits in your garden much more important than they might initially appear.

How confident should you be in the findings?

Confident enough to take them seriously. Not confident enough to treat them as a medical guarantee.

Both major Finnish studies were observational. The researchers recorded what people already did rather than randomly assigning them to different sauna routines.

That means other differences between frequent and infrequent sauna users could contribute to the results. The 2015 researchers explicitly acknowledged the possibility of residual confounding.

The 2018 study also included a small subsidiary analysis that incorporated people who did not use a sauna at all, but its main analysis compared different frequencies of sauna use. The primary research therefore tells us much more about frequency of use among sauna users than it tells us about what would happen if someone who never uses a sauna suddenly started.

And there is an important limitation when interpreting the findings for women. The 2018 study included a substantial number of women and found no statistically significant evidence in the sex-specific analyses, although there was no significant evidence that gender modified the overall association. The number of cardiovascular events in the individual sex-specific groups was relatively small.

So the sensible conclusion is not:

Sauna prevents heart disease.

It is:

Long-term Finnish observational research has found a strong association between frequent traditional sauna use and lower cardiovascular mortality. The finding is consistent and biologically plausible, but further research is needed to establish causation and how broadly it applies outside Finnish sauna culture.

That's a much more useful way to understand the evidence.

Does the research apply to infrared cabins?

This distinction matters.

The two Finnish mortality studies were conducted using traditional Finnish saunas, with average temperatures around 76–79°C. They therefore provide evidence about that type of sauna — not a blanket health claim covering every form of heat cabin.

Infrared cabins operate differently and at substantially lower air temperatures. There is research into infrared sauna and heat therapy, but it is a different evidence base and should not simply inherit the results of the Finnish mortality studies.

So if the Finnish research is one of the reasons you're considering sauna, a traditional sauna is the closest match to what was actually studied.

That doesn't automatically make infrared the wrong choice.

If your priorities are lower-temperature heat, a different style of experience, simpler installation or lower electrical demand, infrared may still make more sense. The important thing is to choose it for what it actually offers rather than assuming that research conducted on a traditional Finnish sauna applies equally to it.

If you're choosing within the traditional category, our guide to wood-fired or electric sauna heaters looks at the practical differences between the two.

What does this mean when choosing a sauna?

If the research tells us anything particularly useful for a buyer, it's that regular use matters.

That puts some surprisingly practical factors near the top of the list.

1. Heat-up time

A sauna that is inconvenient to use is less likely to become part of your routine.

Heater sizing is a major part of that. Harvia's guidance starts with approximately 1 kW of heater power for each cubic metre of sauna volume, but the calculation also needs to account for glass and other uninsulated surfaces. Harvia states that each square metre of glass or similar non-insulated surface can increase the heating requirement by the equivalent of 1.2 cubic metres of sauna volume.

For example, a 2m × 1.8m × 2m cabin has a volume of 7.2m³. Add a large glass front and the effective heating requirement can be considerably higher than the simple volume calculation suggests.

This is why heater selection isn't just a specification to tick off a product page. Get it wrong and the sauna can take longer to reach temperature and the heater may have to work harder than intended.

2. Running cost

Running cost becomes more relevant if you're going to use the sauna regularly.

Harvia gives an example of a well-insulated family sauna with a correctly sized 6 kW heater using around 7–9 kWh over a two-hour heat-and-use period.

At Ofgem's electricity price-cap rate of 26.11p/kWh for 1 July to 30 September 2026, that works out at approximately £1.83–£2.35 per session.

At four sessions a week, that's roughly £7.30–£9.40 per week, or around £380–£490 over a year if the same usage and electricity rate were maintained.

Your actual cost will vary with the heater, cabin, insulation, temperature, weather, tariff and how long you run the sauna.

But the calculation illustrates an important point: if you intend to use a sauna frequently, insulation and heating efficiency matter over the entire life of the sauna, not just on the day you buy it.

3. Somewhere you genuinely want to spend time

A sauna session isn't particularly useful if the cabin is uncomfortable.

The research describes regular sessions and meaningful amounts of time spent bathing, so details such as bench depth, headroom, seating position and whether there is enough room to stretch out become practical considerations rather than cosmetic ones.

This is one reason we don't think a sauna should be assessed from photographs and headline specifications alone.

The question is whether the space will actually work for you.

4. The garden and installation

There is also everything outside the cabin itself.

You'll need to think about:

• access for delivery;
• a suitable level base;
• electrical requirements;
• ventilation;
• drainage where relevant;
• where people will change or cool down;
• and how the sauna sits within the garden.

If you're planning a garden sauna in England, our guide to planning permission explains the relevant permitted-development considerations.

Our guide to what a British winter actually does to a garden sauna looks at year-round ownership, while our space planner can help you work out what will realistically fit.

And if you're ready to compare actual cabins, you can explore the Tarnfell sauna collection, where we focus on the specifications that affect how a sauna performs and feels to own — including the reasons you might decide not to buy each one.

Is a sauna worth buying for your health?

The research is encouraging, but health alone shouldn't be the reason you buy one.

The Finnish studies give us some of the strongest long-term evidence available: frequent traditional sauna use was associated with substantially lower cardiovascular mortality, and the association became stronger as sauna use increased.

But an association isn't a guarantee, and buying a sauna doesn't automatically reproduce the habits of the people in those studies.

The more useful question is whether sauna is something you can see yourself using regularly.

If it is, the research gives you another reason to take the habit seriously. And it makes the practical details of the sauna surprisingly important: how quickly it heats, how comfortable it is, what it costs to run, whether it fits your space and whether you actually enjoy using it.

Because the best sauna isn't necessarily the one with the longest specification sheet.

It's the one you can see yourself getting into on a Tuesday evening, not just the one you're excited to own on the day it arrives.

A final word on safety

Sauna is well tolerated by many healthy adults, but it isn't appropriate for everyone.

The cardiovascular response can be substantial, and sauna also involves significant heat and fluid loss. If you have a cardiovascular condition, take medication that affects blood pressure, are prone to fainting or have another condition that could be affected by heat exposure, it's sensible to discuss sauna use with your doctor before starting.

Pregnancy is a particular case. NHS guidance advises avoiding saunas, hot tubs and steam rooms during pregnancy because overheating can be harmful, particularly during the first 12 weeks.

A sauna isn't a medical treatment, and the research discussed here shouldn't be used as one.

For most prospective buyers, though, the more useful question isn't whether sauna can be turned into a medical prescription.

It's whether regular sauna can become a worthwhile part of your life.

And if you think it can, choosing the right sauna becomes much more interesting.

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Sources

• • Laukkanen et al., Association Between Sauna Bathing and Fatal Cardiovascular and All-Cause Mortality Events, JAMA Internal Medicine, 2015.
  • Laukkanen et al., Sauna bathing is associated with reduced cardiovascular mortality and improves risk prediction in men and women, BMC Medicine, 2018.
  • Harvia, How do I select the correct heater power?
  • Harvia, FAQ about the energy consumption of sauna bathing.
  • Ofgem, Energy price cap unit rates and standing charges.
  • NHS guidance on sauna use during pregnancy.