Overview of What the World's Leading Researchers Think About Saunas
NPR’s Short Wave explores the booming popularity of saunas and heat therapy, separating wellness hype from the actual science. Reporter Will Stone visits Norway for the first-ever symposium on heat therapy and health, where researchers discuss what sauna bathing, infrared heat, and hot-water immersion may really do for the body and mind.
Main Takeaways
- Saunas are having a major comeback in wellness, social, and longevity circles, but much of the online “detox miracle” messaging is ahead of the evidence.
- The science is still young: researchers say heat therapy research is promising, but the field lacks standardized methods, large trials, and reproducible results.
- There are real physiological effects from heat exposure, including increased heart rate, blood vessel dilation, sweating, and activation of heat shock proteins.
- Potential benefits are strongest in cardiovascular and metabolic health, with some studies suggesting improvements in blood pressure, arterial stiffness, blood sugar regulation, and cholesterol-related markers.
- Mental health is an active area of research, with interest in whether sauna use can help with mood, depression, stress, and social connection.
- Experts caution against over-optimizing sauna use: the advice is to start gradually, be safe, and enjoy it rather than treat it like a performance metric.
What Researchers Are Studying
Heat Therapy as a Broader Category
The episode explains that sauna is part of a larger umbrella of heat therapy, which includes:
- Traditional Finnish-style saunas
- Infrared saunas
- Hot water immersion / hot tubs
- Other forms of controlled heat exposure
Why the Field Needs Standardization
Researchers at the Norway symposium are trying to agree on:
- How to define “heat therapy”
- What body measurements should be tracked
- How to report humidity, temperature, and exposure conditions
- Best ways to measure body temperature and response
A major issue: studies have used more than 100 different protocols, making it hard to compare results.
What the Evidence Suggests So Far
Cardiovascular and Metabolic Health
The most convincing early evidence points to possible benefits similar to light exercise, including:
- Lower blood pressure
- Improved vascular function
- Reduced arterial stiffness
- Better blood sugar control
- Possible improvements in cholesterol and metabolism
Researchers are especially interested in whether heat could act as an “exercise mimetic” for people who cannot exercise regularly.
Mental Health and Mood
The episode highlights growing interest in sauna use for:
- Depression
- Stress reduction
- Sleep and mood support
Possible reasons include both:
- Biological effects: heat signaling in the brain overlaps with pathways involved in mood and pleasure
- Lifestyle effects: relaxation, socializing, nature, and time away from phones
Notable Research and Voices
- Ashley Mason (UCSF) is helping organize the field and studies heat therapy for sleep, mood, and depression.
- Ant Shephard / University of Portsmouth is focused on whether heat can benefit people with cardiovascular, metabolic, and age-related conditions.
- Eric Lee (Montreal Heart Institute) has run one of the few randomized controlled trials, finding that sauna use added to exercise may provide extra cardiovascular benefits for at-risk people.
Practical Advice for Sauna Beginners
- Start slow and build up gradually, similar to exercise.
- Don’t assume “more is better”; the goal is safe, sustainable use.
- Track your tolerance if helpful, but don’t turn sauna into another optimization project.
- The researchers’ consensus: enjoy it—the mental and social benefits may matter as much as the physical ones.
Bottom Line
Saunas probably are not a cure-all, but they are also more than a wellness fad. Early evidence suggests real benefits for circulation, metabolism, and possibly mood, though the research is still too immature to support sweeping claims. The episode’s central message is that sauna use may be genuinely helpful—just not magical, and not yet fully understood.