Most people buy an infrared sauna to relax. In Japan, a version of the same heat has been studied as a hospital treatment for heart failure, with trials published since at least 2008.
This page explains that protocol and what its trials found. It is general information, not medical advice. For infrared research beyond Waon, see the overview of infrared sauna benefits.
Short answer: Waon therapy is 15 minutes in a far-infrared sauna at 60°C (140°F), followed by 30 minutes under a blanket. In a 2016 randomized trial of 149 patients with advanced heart failure, 10 daily sessions improved symptoms, walking distance, and heart size, with no serious adverse events. The trial’s main endpoint, a blood marker of heart strain, didn’t change significantly.
The protocol
Every trial below used the same steps, so the protocol is easy to state precisely:
- Sit or lie in a far-infrared dry sauna held at 60°C (140°F) for 15 minutes.
- Move to a room at normal temperature and rest under a blanket for 30 minutes.
- Repeat, daily in most of the trials.
The blanket phase holds the warmth after the sauna. In the 2021 blood pressure study, staff also weighed patients before and after and rehydrated them based on the weight they lost.
What the trials found
| Study | Design | People | Result |
|---|---|---|---|
| Miyata (2008), Journal of Cardiology | Randomized, 2 weeks of daily sessions | 188 with heart failure | Symptom class and heart size improved in both groups |
| Kihara (2009), Journal of Cardiology | Matched controls, 5-year follow-up | 129 with severe heart failure | Heart failure events or cardiac death: 31.3% vs 68.7% |
| Tei (2016), Circulation Journal | Randomized, 19 hospitals, 10 days | 149 with advanced heart failure | Better symptoms, walk distance, heart size; BNP not significant |
The WAON-CHF authors concluded:
“Waon therapy, a holistic soothing warmth therapy, showed clinical advantages in safety and efficacy among patients with advanced HF.”
Tei C et al., Circulation Journal, 2016
Neither group had serious adverse events.
Beyond the heart
The same group tested Waon therapy for other conditions, in small studies without control groups. Matsushita (2008) found pain fell by about half after the first session in 13 women with fibromyalgia. Soejima (2015) found perceived fatigue fell after 4 weeks in 10 inpatients with chronic fatigue syndrome, though pain did not change.
Limitations
Many of the trials came from the research group that developed Waon therapy. In WAON-CHF, the treated and control groups differed in body mass index and how many had diabetes. The 5-year Kihara study matched its groups rather than randomizing. Patients in the trials also received standard heart failure treatment.
Here’s what the spec sheet won’t tell you. A home cabin set to 60°C isn’t the same as a hospital protocol: the trials added supervised rest, weighing, and fluids, and enrolled patients under a cardiologist’s care.
My rule of thumb: read Waon results as evidence about a supervised treatment, not as proof that a home cabin treats anything.
Bottom line: Waon therapy has the most consistent infrared sauna trials, all in supervised heart failure care in Japan, with improved symptoms and no serious adverse events reported. For the broader infrared evidence, see the benefits overview linked above.
Sources
- Tei C et al., “Waon Therapy for Managing Chronic Heart Failure: Results From a Multicenter Prospective Randomized WAON-CHF Study,” Circulation Journal, 2016;80:827-834 (abstract): pubmed.ncbi.nlm.nih.gov
- Miyata M et al., “Beneficial effects of Waon therapy on patients with chronic heart failure: results of a prospective multicenter study,” Journal of Cardiology, 2008;52:79-85 (abstract): pubmed.ncbi.nlm.nih.gov
- Kihara T et al., “Waon therapy improves the prognosis of patients with chronic heart failure,” Journal of Cardiology, 2009;53:214-218 (abstract): pubmed.ncbi.nlm.nih.gov
- Matsushita K, Masuda A, Tei C, “Efficacy of Waon therapy for fibromyalgia,” Internal Medicine, 2008;47:1473-1476 (abstract): pubmed.ncbi.nlm.nih.gov
- Soejima Y et al., “Effects of Waon therapy on chronic fatigue syndrome: a pilot study,” Internal Medicine, 2015;54:333-338 (abstract): pubmed.ncbi.nlm.nih.gov
- Kominami K et al., “Blood pressure-lowering effect of repeated Waon therapy in non-smokers with hypertension,” Medicine, 2021;100:e26266: europepmc.org
- Cleveland Clinic, “6 Possible Benefits of Infrared Saunas,” October 9, 2026: health.clevelandclinic.org