Recap answer: The clinical studies behind far infrared sauna therapy didn’t just study the sauna alone. They studied the sauna plus a structured rest period afterward, usually about 30 minutes of quiet, warm, seated, or lying-down recovery. If you step out of the cabin and get straight back into your day, you’re running half of the protocol that was actually tested. Below, I’ll walk through what the research protocols looked like, what your body is doing in that window, and how to build an effective post session cool-down.

The part nobody talks about

Almost everything written about saunas is about what happens inside the cabin and that’s valid. How hot. How long. How many times a week. I’ve written some of that myself, including our guide on how often to use an infrared sauna.

But the studies that produced the most encouraging results weren’t testing a sauna session. They were testing a sauna session followed by a very specific rest period, and the rest period was written into the protocol with the same precision as the temperature and the duration.

What the research protocols actually looked like

The bulk of the clinical far infrared research comes out of Japan under the name Waon therapy, a standardized protocol developed by Dr. Chuwa Tei and colleagues. Here’s how the sessions were structured:

  • In the chronic fatigue syndrome pilot study, patients spent 15 minutes in a 140°F far infrared sauna, then rested on a bed under a blanket for an additional 30 minutes outside the sauna room, once a day, five days a week, for four weeks (1).
  • In the fibromyalgia study, the structure was identical: 15 minutes at 140°C, then 30 minutes covered with a blanket in a room held at 78°F.

Notice the ratio. Fifteen minutes of heat, thirty minutes of rest. The recovery period was twice as long as the session. And it wasn’t described as “afterward” or “then patients went home.” It was part of the treatment being administered.

I want to be careful here, and I’ll come back to this at the end: no study has compared sauna-with-rest against sauna-alone. So we know the rest period was present in the protocols that worked. We can’t yet say with certainty that it was responsible. But when every clinical protocol in a field independently includes the same element, that’s worth taking seriously rather than discarding because it’s inconvenient.

Japan Waon Therapy

What’s actually happening in those 30 minutes

Here’s the physiology, and it explains why the cool-down is an important piece of the puzzle.

Your heat load hasn’t gone anywhere. When you step out of the cabin, your core temperature is still elevated and your body is still working to shed that heat. The thermoregulatory response doesn’t switch off when the door opens. It continues, often for 20 minutes or more.

Your blood vessels are still wide open. Peripheral vasodilation, the dilation of blood vessels near the skin surface, is one of the primary responses to heat exposure. It persists after the session. This is why standing up quickly and moving around briskly can leave people lightheaded. Blood has been redistributed toward the periphery, and your cardiovascular system needs a few minutes to re-regulate.

You’re often still sweating. Many people shower immediately, which cuts short the sweat response before it’s finished. Giving it a few minutes to complete on its own is both more comfortable and more sensible before you shower.

Your nervous system is coming back from a stress signal, not resting in one. This is the part that surprises people most, so it deserves its own section.

Heat isn’t relaxing. Recovering from heat is.

There’s a widespread assumption that sitting in a sauna calms your nervous system. The physiology doesn’t support that, at least not in the way people mean it.

Heat is a mild stressor. That’s the entire point, and it’s the same reason exercise works. During the session, your heart rate rises and your sympathetic nervous system, the “activation” branch, is engaged. In a randomized crossover trial in trained athletes, an infrared sauna session after resistance training produced a higher heart rate and lower heart rate variability than passive recovery (3). Not a calming effect. An activating one.

The parasympathetic side, the “rest and repair” branch, comes into play during the return to baseline. That’s the cool-down. That’s your post session window.

There’s some interesting nuance in the broader research too. In a randomized study of 44 adults over 50, forty minutes of far infrared exposure significantly increased both the low-frequency and high-frequency components of heart rate variability without changing the ratio between them (4). In plain terms: the autonomic nervous system became more responsive overall, rather than one branch simply overtaking the other. A more responsive system is generally the goal.

If you want to go deeper on the stress side of this, my colleague Dr. Dubec wrote a good piece on sauna, cortisol, and stress resilience that pairs well with this article.

How to use your post sauna window

Here’s the practical part. None of this is complicated, and most of it costs you nothing but a little patience.

  1. Sit before you stand. After a session, open the sauna door and give yourself three to five minutes on the bench before you get up, especially if you’re new to sauna use or ran a longer session. Peripheral blood vessels are still dilated and blood has been redistributed toward your skin. This is the moment people are most likely to feel lightheaded, and going right into a hot shower is the worst place to discover that.
  2. Take a quick warm rinse. Sweat carries trace amounts of heavy metals and other compounds to the skin surface, and as it dries, that residue concentrates on warm, hydrated, more permeable skin so a quick rinse will get that off. Keep the water warm rather than cold. A cold rinse cuts short the cool-down you’re heading into. Then wrap up for the rest of the window.
  3. Settle in and stay warm. This runs counter to instinct, you’re hot, so you want to cool off. But the clinical protocols kept people wrapped in a blanket in a room in the mid-70s Fahrenheit. Blasting yourself with air conditioning or a cold rinse right away cuts the process short. Let your body do the work of coming down on its own.
  4. Rehydrate deliberately, with electrolytes. Water alone doesn’t replace what you lost. Sodium is the mineral you lose in the greatest quantity through sweat, and this is where most people under-do it. We covered this in detail in our guide to hydration and electrolytes for sauna users.
  5. Keep the stimulation low. No email, no news, no phone calls. You’ve just handed your body a recovery signal. Don’t immediately overwrite it with a different one. This is a good window for reading, meditating, or quiet music.

How long? Twenty to thirty minutes is a reasonable target for most people. If that’s genuinely impossible on a given day, ten focused minutes still beats zero. The goal is to make the cool-down a real part of your routine rather than the thing that gets cut whenever you’re running behind.

Waon Cooldown period

Where our Smart Sauna actually helps here

Post session cool-downs get skipped for one main reason: time pressure. And a large share of that time pressure comes from a single source, which is waiting around for the sauna to heat up.

If you’ve budgeted 60 minutes, spent 20 of them waiting for the cabin to reach temperature, and then done a 30-minute session, you have 10 minutes left and something has to give. It’s always the cool-down.

Our Transcend Smart Sauna series lets you schedule sessions ahead or start the sauna remotely from the app, so it’s at temperature when you walk in. That’s not a therapeutic claim about the sauna itself (the heaters are the same best heaters as in our Transcend Model), it’s a scheduling claim. It gives you back the twenty minutes you were spending on preheat, and those are exactly the minutes the cool-down needs. Our included Sauna Guide™ can also help you plan the full session, cool-down included, rather than just the time in the cabin.

Putting it together

  • The session doesn’t end when the door opens. Plan for 20 to 30 minutes on the other side of it.
  • Stay warm and stay seated in your sauna for the first few minutes after a session rather than cooling down too quickly.
  • Let the sweat response finish then take a quick warm shower.
  • Rehydrate with electrolytes, not just water.
  • Wrap up, stay warm, and relax for 10 – 20 minutes.
  • Protect the window from stimulation. It’s a recovery signal. Don’t interrupt it.
  • Solve the preheat problem so the cool-down isn’t the thing that gets cut.

If you’d like help building a routine that fits your life, cool-down included, call us at 1-800-794-5355 and speak with one of our expert sauna specialists. We’re all health professionals, and this is exactly the kind of thing we’re good at.

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References

1. Yuji Soejima, Takao Munemoto, Akinori Masuda, Yuuki Uwatoko, Masaaki Miyata, Chuwa Tei, Effects of Waon Therapy on Chronic Fatigue Syndrome: A Pilot Study, Internal Medicine, 2015, Volume 54, Issue 3, Pages 333-338, Released on J-STAGE February 01, 2015, Online ISSN 1349-7235, Print ISSN 0918-2918, https://doi.org/10.2169/internalmedicine.54.3042, https://www.jstage.jst.go.jp/article/internalmedicine/54/3/54_54.3042/_article/-char/en

2. Kakushi Matsushita, Akinori Masuda, Chuwa Tei, Efficacy of Waon Therapy for Fibromyalgia, Internal Medicine, 2008, Volume 47, Issue 16, Pages 1473-1476, Released on J-STAGE August 15, 2008, Online ISSN 1349-7235, Print ISSN 0918-2918, https://doi.org/10.2169/internalmedicine.47.1054, https://www.jstage.jst.go.jp/article/internalmedicine/47/16/47_16_1473/_article/-char/en

3. Ahokas EK, Ihalainen JK, Hanstock HG, Savolainen E, Kyröläinen H. A post-exercise infrared sauna session improves recovery of neuromuscular performance and muscle soreness after resistance exercise training. Biol Sport. 2023 Jul;40(3):681-689. doi: 10.5114/biolsport.2023.119289. Epub 2022 Sep 15. PMID: 37398966; PMCID: PMC10286597.

4. Lin, L.-M., Chi, L.-M., Chang, S.-P., & Peng, T.-C. (2020). The effectiveness of far-infrared irradiation on foot skin surface temperature and heart rate variability in healthy adults over 50 years of age: A randomized study. Medicine, 99(50), e23366. https://doi.org/10.1097/MD.0000000000023366