The Benefits of Sauna - Dr Rhonda Patrick

Learning Points

1. Broad Spectrum of Benefits
   • Sauna use is associated with a lower risk of death from cardiovascular disease, sudden cardiac death, coronary heart disease, stroke, dementia, and Alzheimer's disease.
   • There is also a 40% lower risk of dying from all causes of death for frequent users.
   • Sauna use contributes to improving "health span," which means extending the youthful part of life and improving the quality of life by preventing or delaying diseases like Parkinson's, Alzheimer's, cancer, cardiovascular disease, and type 2 diabetes.
2. Dose-Dependent Effects
   • The health benefits of sauna bathing are dose-dependent, meaning more frequent use leads to more robust effects.
   • For example, using the sauna 4 to 7 times a week significantly reduces the risk of sudden cardiac death (63% lower) compared to once a week (22% lower for 2-3 times/week).
   • Similarly, 4-7 times a week is associated with a 60-66% reduction in dementia and Alzheimer's risk compared to once a week.
3. Sauna as a Mimic of Moderate Aerobic Exercise
   • Sauna use essentially mimics moderate aerobic cardiovascular exercise, producing many of the same physiological responses.
   • These include elevated heart rate (to around 120 beats per minute), elevated core body temperature, sweating, increased blood flow to the skin and muscles, and a subsequent lowering of blood pressure and resting heart rate.
   • This "proof of principle" suggests that sauna is beneficial for cardiovascular health for similar reasons to exercise.
4. Cardiovascular Health Benefits
   • Frequent sauna use (4-7 times/week) can lower stroke risk by about 40%.
   • It also significantly reduces the risk of hypertension in a dose-dependent manner (24% lower for 2-3 times/week; 46% lower for 4-7 times/week).
   • Even a single sauna session can lower both systolic and diastolic blood pressure.
5. Endurance and Fitness Improvement
   • Sauna use may improve endurance exercise and overall fitness, as observed in studies with runners and people training in sauna suits.
   • Heat acclimation, where the body adapts to heat stress by sweating at a lower core body temperature, helps improve tolerance to heat during other activities like running.
6. Brain Health and Neurodegenerative Disease Protection
   • Observational studies show a significant association between frequent sauna use and a lower risk of Alzheimer's disease and dementia.
   • Mechanisms for brain protection include:
     • Improved cardiovascular health leading to increased blood flow to the brain.
     • Activation of heat shock proteins (HSPs), which help maintain the proper three-dimensional structure of proteins inside cells, preventing disorganization, aggregation, and plaque formation (e.g., amyloid-beta plaques associated with Alzheimer's disease). HSPs remain elevated for about 48 hours after a session.
     • Potential increase in Brain-Derived Neurotrophic Factor (BDNF), a growth factor that protects existing neurons, may help grow new neurons in adults, and plays a role in neuroplasticity (the brain's ability to rewire itself and cope with changing environments), which is important for preventing depression.
7. Mental Health and Mood Improvement
   • Sauna use can reduce stress and anxiety.
   • It leads to the release of endorphins (feel-good opioids) and dynorphin (associated with dysphoric feelings). The production of dynorphin, by binding to kappa opioid receptors, can sensitize mu opioid receptors (where endorphins bind), potentially making one more sensitive to endorphin release from everyday activities later on.
   • Studies have shown that a single sauna session (elevating core body temperature by 1-2 degrees) can have an antidepressant effect lasting up to six weeks in depressed patients.
   • Sauna use is associated with lower biomarkers of inflammation (e.g., C-reactive protein) and increases anti-inflammatory cytokines (like IL-10 and potentially IL-6), which may play a role in its antidepressant effects.
8. Cellular Repair Mechanisms and Hormesis
   • Sauna stress activates beneficial cellular response pathways, a concept known as hormesis.
   • These pathways include:
     • Heat shock proteins (HSPs): Essential for protein folding and preventing aggregation.
     • Nrf2: A major regulator of antioxidant, detoxification, and anti-inflammatory genes.
     • Autophagy: The cellular cleaning process that removes damaged components.
     • Pathways involved in making new stem cells and repairing DNA damage.
9. Muscle Preservation
   • Sauna use has been shown in human and animal studies to prevent muscle atrophy from disuse, possibly through the activation of heat shock protein 72. This has implications for sarcopenia and maintaining muscle mass, especially for those unable to exercise.
10. Detoxification
    • Sauna use can help excrete heavy metals (e.g., cadmium, aluminum) and other compounds like phthalates and BPA through sweat, particularly those predominantly eliminated via sweat.
11. Heart Rate Variability (HRV) Improvement
    • Sauna use increases heart rate variability, a marker of how well the heart can handle stress, by increasing parasympathetic activity and lowering sympathetic activity, similar to exercise.
12. Synergy with Exercise
    • While exercise is "king" for overall health, combining exercise with sauna use leads to better cardiorespiratory fitness than either alone.
    • Sauna can also be a valuable tool for individuals who cannot perform physical activity to improve cardiovascular and brain health.
13. Cultural Context and Types of Saunas
    • Sauna use is deeply ingrained in cultures like Finland (where nearly everyone has one), Russian banyas, and Native American sweat lodges.
    • Traditional saunas use a heater to warm ambient air (up to ~200°F), often with hot rocks and humidity (10-20%). Most research comes from studies using traditional Finnish saunas.
    • Infrared saunas use thermal radiation to heat the body directly, reaching lower temperatures (~140°F). There is less scientific evidence for infrared saunas compared to traditional ones, but some Japanese "waon therapy" protocols using infrared have shown cardiovascular benefits.

Action Points

1. Temperature and Duration
   • Based on Finnish studies, aim for approximately 174°F (around 80°C).
   • Duration is crucial: stay in the sauna for greater than 19 minutes (around 20 minutes) per session to achieve robust cardiovascular benefits. Shorter durations (e.g., 11 minutes) show significantly less benefit.
   • For activating heat shock proteins, 163°F for 30 minutes showed a 50% increase over baseline.
   • Dr. Patrick's personal protocol involves 186°F for 20-30 minutes, often immediately after a high-intensity workout, with 10-20% humidity. She is highly heat-adapted, so beginners should start slower.
2. Frequency
   • The sweet spot for robust benefits is 4 to 7 times a week. Dr. Patrick aims for around 4 times a week.
3. Humidity
   • Many beneficial studies incorporated 10-20% humidity (achieved by pouring water over hot rocks).
4. Listen to Your Body and Build Tolerance
   • If new to saunas, it will be hard to stay in a hot sauna for more than five minutes.
   • Gradually build heat tolerance. Get out when your heart rate gets very fast and you feel "really, really uncomfortable". Don't just get out at the "slightest bit of uncomfortableness".
   • Use a timer outside the sauna to track duration and prevent accidentally falling asleep, especially if prone to it. If you might fall asleep, ensure someone is with you.
5. Hydration
   • It's important to stay well-hydrated before and after sauna use, as significant sweat and electrolyte (especially sodium, magnesium, potassium) loss occurs.
   • Consider electrolyte supplements or green juices.
6. Hot Baths/Jacuzzis as Alternatives
   • Hot baths (around 104°F, submerged shoulders down for 20 minutes) and jacuzzis appear to offer similar benefits to saunas, including elevating heat shock proteins, BDNF, and effects on depression and cardiovascular health, although more empirical evidence is needed.
   • Hot showers are unlikely to provide the same intense heat and benefits as a hot bath or sauna.
7. Safety and Contraindications
   • Consult a physician before using a sauna, especially if you have existing health conditions.
   • Never consume alcohol in or before going into a sauna, as it can be very dangerous and even deadly.
   • Elderly individuals prone to very low blood pressure should exercise caution.
   • Individuals with recent heart attack, unstable angina pectoris, or severe aortic stenosis should avoid saunas. Those with stable cardiac disease should still consult their doctor.
   • Children: Young children do not have the same thermal regulation mechanisms as adults; anything more than five minutes can be dangerous. Specific cultural guidelines exist for very short exposures in older children.
   • Pregnant women: Avoid sauna use as it can lead to fetal abnormalities, similar to hot tubs. Dr. Patrick personally avoided it during her pregnancy.
8. Continuous Glucose Monitors (CGM)
   • Temporary, transient glucose level rises may be observed during sauna use on a CGM, possibly due to fluid loss through sweating increasing the concentration of sugar in the blood. This is typically not a concern as long-term sauna use is associated with improved fasting glucose and insulin sensitivity.
9. Combine with Other Healthy Practices
   • Sauna use is another important lifestyle factor, alongside exercise, good sleep, a healthy diet, and meditation, that can improve overall health and health span.
   • Consider using the sauna to be efficient: meditate, listen to podcasts, or engage in creative thinking while in the sauna.