Sauna blankets and pop up sauna tents are everywhere right now, and most of them are sold on the back of the same research: big Finnish studies that linked regular sauna use with fewer heart related deaths. The catch is that those studies weren't done in a blanket or a tent. They were done in hot, dry Finnish saunas, and the temperatures are not close.
This post compares the heat in the studies with the heat portable units list on their own spec pages, explains what the research can and can't tell you, and covers the habit with even stronger evidence for your heart: getting fitter.
Please read first. This post is general information, not medical advice. Heat puts real strain on your heart and blood vessels. If you have heart disease, high or low blood pressure, are pregnant, take medication that affects heat or blood pressure, or have any medical condition, talk to your doctor before using any sauna. Don't use heat after drinking alcohol, and stop if you feel dizzy, faint, sick or confused. If those feelings don't pass quickly once you cool down, or you have chest pain, get medical care.
How hot were the saunas in the studies?
The study most sauna ads point to followed 2,315 men in eastern Finland for a median of 20.7 years (Laukkanen et al., 2015). The men reported how often they used a sauna, for how long and how hot it was, using the thermometer in their own sauna.
- The average sauna was 78.9°C. The range was 40 to 100°C, and the usual recommended temperature for a Finnish sauna is 80 to 100°C at face level, with dry air (10 to 20% humidity).
- Sessions averaged about 14 minutes, 2.1 times a week.
- More sauna, fewer deaths. Compared with once a week, men who used a sauna 4 to 7 times a week had a 63% lower risk of sudden cardiac death after adjusting for other risk factors (hazard ratio 0.37). The same pattern showed up for fatal heart disease and death from any cause.
The authors were careful about how far this goes. They wrote that their results, from saunas averaging 79°C, "cannot be directly applied to steam rooms, hot tubs, and some other types of saunas, which may operate at lower temperatures than a typical Finnish sauna" (Laukkanen et al., 2015).
A systematic review of 40 sauna studies found the same split. Finnish style saunas in the research ran at 80 to 90°C, while infrared sauna cabins generally run at 45 to 60°C, and most of the infrared studies were small (Hussain and Cohen, 2018).
How hot do portable saunas get?
Here's what manufacturers list for some popular portable units. These are the makers' own maximums, not independent measurements.
- Infrared sauna blanket (HigherDOSE): "up to 175 degrees F" (about 79°C) at the top setting. That's the heat of the blanket itself, which you lie inside wearing long sleeves, pants and socks.
- Steam sauna tent (SaunaBox SmartSteam Pro): 54 to 60°C (130 to 140°F).
- Pop up steam tent (Hazemor): up to 55°C (131°F).
So the steam tents sit at 55 to 60°C, well below the 80 to 100°C a traditional sauna runs at. The blanket's top setting is close to the average in the Finnish study, but it's a heated wrap around your body, not a room of hot air, so the two numbers don't compare directly.
One fair point in their favour: steam tents are humid, and moist heat feels hotter and loads the body more than dry air at the same temperature, which SaunaBox notes on its own page. That's also why you can't simply compare numbers. The truth is that nobody has run long term studies on sauna blankets or tents, so their effect on your heart is unknown, not proven and not disproven.
How hot is your sauna?
Bar length shows temperature in °C. Studies on the left, portable units listed by their makers.
Why the big studies can't prove a sauna caused the benefit
The Finnish sauna research is observational. It found that men who used saunas more often died less often, but it can't rule out that healthier men simply used the sauna more. The authors adjusted for many risk factors and still note that "potential for residual confounding remains" (Laukkanen et al., 2015). The 2018 review in Mayo Clinic Proceedings summed up the field as "emerging evidence" that sauna bathing "may be linked" to several health benefits (Laukkanen et al., 2018).
That doesn't make saunas useless. It means that the strongest claims you see in ads go further than the studies do, especially for a device that never gets as hot.
Fitness did more than sauna use in the same men
Here's the part the ads leave out. The same Finnish research team measured the men's cardiorespiratory fitness, meaning how well the heart and lungs supply oxygen during hard exercise, using a lab exercise test. Then they looked at fitness and sauna habits together in 2,277 men over a median of 26.1 years (Kunutsor et al., 2018).
Compared with men who had low fitness and used a sauna 2 times a week or less:
- Frequent sauna use with low fitness: 28% lower risk of dying from heart disease (hazard ratio 0.72).
- High fitness with infrequent sauna use: 50% lower risk (hazard ratio 0.50).
- High fitness and frequent sauna use: 58% lower risk (hazard ratio 0.42).
A second analysis looked at sudden cardiac death. There, frequent sauna use with low fitness wasn't clearly linked to lower risk (hazard ratio 0.71, with a confidence interval that crossed 1), while high fitness alone was linked to 51% lower risk (Laukkanen et al., 2018b).
These are also observational results, so they show links, not proof. Still, in the very studies sauna ads rely on, being fit was linked to more protection than sauna use on its own. The best numbers came from doing both, with a real Finnish sauna.
Fitness or sauna: which mattered more?
Same Finnish men, sorted by fitness test results and sauna habits. Switch views to compare outcomes.
If you already own a portable sauna
- Treat it as a way to relax, not a heart treatment. Enjoying the warmth is a fine reason to use it, but don't expect it to do what the Finnish sauna studies found.
- Follow the maker's limits. HigherDOSE, for example, suggests 30 to 50 minutes per session and says your skin should be covered so it doesn't touch the heated surface.
- Drink water and skip alcohol. A review of sauna safety notes that half or more of sauna deaths in the reports it covered involved alcohol (Hussain and Cohen, 2018).
- Don't let it replace exercise. If you're choosing where to spend your time, the fitness data above points to moving more.
How to build the fitness that counts
Cardiorespiratory fitness goes up when you train your heart and lungs regularly and build up over time. A practical week looks like this:
- Two or three conditioning sessions a week that get you breathing hard, built up over a few weeks.
- Two strength sessions a week for your major muscle groups.
- Walk on the other days if you can.
- Add yoga or breathwork if you want a calm way to wind down.
How we can help
At Inner G, a fitness studio in Concord, our coaches run small group classes in strength, conditioning, mobility, yoga and breathwork, capped at 16 people. Conditioning classes are where you build the heart and lung fitness that the Finnish research linked to lower risk, and a coach scales every session to where you are. If you'd rather start one on one, a coach can set up a plan designed around your schedule, your experience and any advice from your doctor.
We don't have a sauna at the studio, and we're coaches, not doctors.
- Try 7 days of unlimited classes for $30. Join by day 5 and your $30 is credited toward your membership. Book your class.
- Prefer one on one? See personal training in Vaughan or one on one training focused on balance and strength.
- Planning cardio and strength in the same week? Read balancing strength training with cardio.
Questions? Call (289) 536-8066 or email g-squad@innerg.ca.
References
HigherDOSE. (n.d.). Infrared Sauna Blanket [product page]. Accessed October 28, 2026. higherdose.com
Hazemor. (n.d.). Hazemor Instant Sauna Tent [product page]. Accessed October 28, 2026. hazemor.com
Hussain J, Cohen M. (2018). Clinical effects of regular dry sauna bathing: a systematic review. Evidence-Based Complementary and Alternative Medicine, 2018:1857413. doi:10.1155/2018/1857413. PubMed · PMC
Kunutsor SK, Khan H, Laukkanen T, Laukkanen JA. (2018). Joint associations of sauna bathing and cardiorespiratory fitness on cardiovascular and all-cause mortality risk: a long-term prospective cohort study. Annals of Medicine, 50(2):139-146. doi:10.1080/07853890.2017.1387927. PubMed
Laukkanen JA, Laukkanen T, Kunutsor SK. (2018). Cardiovascular and other health benefits of sauna bathing: a review of the evidence. Mayo Clinic Proceedings, 93(8):1111-1121. doi:10.1016/j.mayocp.2018.04.008. PubMed
Laukkanen JA, Laukkanen T, Khan H, Babar M, Kunutsor SK. (2018b). Combined effect of sauna bathing and cardiorespiratory fitness on the risk of sudden cardiac deaths in Caucasian men: a long-term prospective cohort study. Progress in Cardiovascular Diseases, 60(6):635-641. doi:10.1016/j.pcad.2018.03.005. PubMed
Laukkanen T, Khan H, Zaccardi F, Laukkanen JA. (2015). Association between sauna bathing and fatal cardiovascular and all-cause mortality events. JAMA Internal Medicine, 175(4):542-548. doi:10.1001/jamainternmed.2014.8187. PubMed
SaunaBox. (n.d.). SaunaBox SmartSteam Pro [product page]. Accessed October 28, 2026. saunabox.com
Want a coach to do this with you? See personal training in Vaughan or small group fitness classes.