The Science of Heat: Sauna Protocols for Health, Recovery, and Longevity

By Dr. Mark Kovacs, PhD, FACSM, CSCS
Human Performance Strategist | Sport Scientist | Longevity Expert

​Introduction
Across centuries and continents, sauna bathing has served as a ritual of cleansing, recovery, and rejuvenation. From the Finnish sauna (traditional sauna) to modern infrared cabins, the act of purposeful heat exposure is more than just a tradition — it's a science-backed practice with profound effects on human health, athletic recovery, and longevity. Having used sauna’s as an athlete first and then for the last two decades advising national sports federations, pro sports team and the top wellness and longevity centers, this article is a summary guide about what the differences are in the major sauna options and also what to look forward if you are considering purchasing a product. The field has become complicated and many large companies who should have expert advisors working with them are still making major mistakes in the types of saunas they are purchasing and not providing accurate or appropriate protocols for their members, guests and athletes. The hope is that this will help individuals and corporations make better decisions and provide the consumer (user) with a better experience and help them in their health and performance journey.
In this guide, we will explore:

• The types of saunas and how they work
• Optimal temperatures and durations
• Physiological and molecular mechanisms of benefit
• Synergistic strategies such as contrast therapy
• Specific protocols for health, performance, and lifespan extension

*Remember to speak with your healthcare providers regarding your specific case. This article is for educational purposes.

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Types of Saunas
1. Traditional Finnish Sauna (Dry Sauna)
This high-temperature, low-humidity sauna is typically heated with a wood or electric stove. Temperatures range between 70°C to 100°C (158°F to 212°F), with humidity around 10–20%. Water is occasionally poured on rocks to increase perceived heat without drastically raising humidity.
Benefits: Elevates core body temperature rapidly, stimulates cardiovascular adaptation, increases sweat rate.
 
2. Steam Sauna (Wet Sauna)
Also known as a steam room or Turkish bath, this uses moist heat. Temperatures are lower, around 40°C to 50°C (104°F to 122°F), but humidity reaches 100%.
Benefits: Effective for skin hydration, respiratory benefits, and relaxation; less cardiovascular stress due to lower temperature.
 
3. Infrared Sauna
This modern sauna type uses infrared radiation (IR) to directly heat the body without significantly warming the surrounding air. Typical temps range from 45°C to 65°C (113°F to 149°F).
Benefits: Deeper tissue penetration with lower environmental heat load. Often preferred for joint pain, muscle recovery, and individuals sensitive to high heat.

Understanding Infrared Radiation in Saunas: Wavelengths and What to Look For
Infrared saunas differ from traditional saunas by using infrared light to directly heat the body rather than the surrounding air. This results in lower ambient temperatures while still achieving deep tissue heat penetration. This combination makes it more tolerable for longer sessions, especially for individuals sensitive to high heat.

• Infrared Radiation Basics

Infrared radiation (IR) falls just below the visible light spectrum and is categorized into three subtypes based on wavelength:

Most commercial far-infrared saunas use ceramic or carbon heating panels that emit radiation in the 6–12 µm range — ideal for penetrating skin and raising core body temperature.

What to Look for When Choosing an Infrared Sauna

1. Wavelength Range
   • Look for full-spectrum infrared saunas if you want exposure to all three types (NIR, MIR, FIR).
   • For cardiovascular, detox, and relaxation benefits, FIR (6–12 µm) is well-supported in research (Laukkanen et al., 2018).
2. Heater Technology
   • Carbon fiber panels offer broader surface heating and lower EMF.
   • Ceramic heaters produce higher heat intensity but may have narrower coverage.
3. Low EMF & ELF Ratings
   • Choose models tested for low electromagnetic fields (EMF) and extremely low frequency (ELF) radiation for safety.
4. Temperature Settings
   • Ideal operating temperatures range between 45°C and 65°C (113°F–149°F).
   • Sessions typically last 20–40 minutes, depending on tolerance and purpose.
5. Certifications
   • Ensure the sauna is ETL, CE, or ISO certified, and that wood materials are non-toxic and untreated.
6. Near-Infrared Add-Ons
   • Some units include near-infrared light therapy panels (or LEDs in the 800–850 nm range), which may support mitochondrial health and skin regeneration.

 
4. Far-Infrared and Near-Infrared
Some infrared saunas offer near-infrared (NIR) or far-infrared (FIR) light. FIR is more commonly used in wellness centers and has been shown to enhance detoxification and promote mild cardiovascular effects (Laukkanen et al., 2018).
 
Near-Infrared (NIR) vs. Far-Infrared (FIR): What’s the Difference — and Why It Matters
 
Modern infrared saunas often distinguish themselves by offering different infrared light spectra: near-infrared (NIR) and far-infrared (FIR). Each penetrates the body differently, activates distinct physiological responses, and may be more or less appropriate depending on your goals - whether it’s skin health, detoxification, cardiovascular conditioning, or mitochondrial stimulation.
 
Far-Infrared (FIR)

• Wavelength: 5.6 to 1000 microns (µm), most commonly 6–12 µm in wellness devices
• Penetration: 1–2 inches (2.5–5 cm) into soft tissue
• Mechanism: FIR waves resonate with water molecules in the body, generating heat through vibrational energy and increasing internal body temperature without significantly raising ambient air temperature.

 
Documented Benefits:

• Cardiovascular effects: Increases heart rate and blood flow similarly to moderate aerobic exercise (Laukkanen et al., 2018; Beever, 2010).
• Detoxification: Promotes sweating and mobilization of fat-stored toxins (Crinnion, 2011).
• Inflammation and pain reduction: Shown to reduce chronic pain and stiffness in rheumatoid arthritis and fibromyalgia (Masuda et al., 2005).
• Stress relief: Supports parasympathetic activation and may improve HRV (Kaura et al., 2021).

 
Who Should Use FIR?

• Individuals focused on detox, cardiovascular health, or chronic stress recovery
• Those with low heat tolerance (FIR saunas feel cooler)
• Older adults seeking gentle metabolic stimulation

 
 
Near-Infrared (NIR)

• Wavelength: 0.7 to 1.4 µm (often focused in the 800–850 nm range for therapeutic use)
• Penetration: Primarily affects the epidermis and upper dermis (few millimeters)
• Mechanism: NIR light interacts directly with mitochondria, especially cytochrome c oxidase, to stimulate ATP production, cellular repair, and growth factor release.

 
Documented Benefits:

• Skin rejuvenation and collagen production
• Wound healing acceleration
• Mitochondrial biogenesis
• Immune modulation and anti-inflammatory effects at the cellular level (Hamblin, 2017)

 
Often Delivered Via:

• LED panels or laser diodes (not heating elements)
• Integrated into saunas labeled as “full-spectrum” infrared

 
Who Should Use NIR?

• Individuals interested in skin health, photobiomodulation, or athletic recovery
• Biohackers targeting cellular rejuvenation and energy optimization
• People recovering from injury or surgery

 
Pro Tip: Many high-end saunas now offer full-spectrum technology, incorporating NIR, MIR, and FIR in a single session. If you're seeking broad-spectrum benefits, including deep tissue heating and mitochondrial activation, this is your best bet. Ideally you would like to be able to turn on and off the different options based on how best you may want to use it.
 
What to Look for When Buying

• FIR Only: Most infrared saunas fall into this category. Look for a FIR range of 6–12 µm, low EMF, and carbon or ceramic panels.
• Full-Spectrum: Look for explicitly labeled NIR and FIR emitters, especially if photobiomodulation or skin therapy is part of your goal.
• Wavelength Clarity: Reliable manufacturers list specific wavelength bands (e.g., “850 nm NIR LED” or “6–12 µm FIR panel”).
• Independent Testing: Ensure the unit is certified for EMF, electrical safety, and wood toxicity (ETL, CE, RoHS).

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Why Most People Do Not Use the Infrared Sauna’s Correctly. The Distance Matters!
How Close Should You Be to Infrared Light?
✅ For Near-Infrared (NIR) Light Therapy

• Ideal Distance: 6 to 24 inches (15 to 60 cm) from the light source
• Why: At this range, irradiance (light intensity) is strong enough to stimulate mitochondrial cytochrome c oxidase without overheating the skin.
• Session Duration:
  • 6–12 inches away → ~5–10 minutes per area
  • 18–24 inches away → ~10–20 minutes per area

⚠️ Being too close (under 4–6 inches) can create excessive heat, which may cause surface skin irritation without improving mitochondrial absorption.
 
✅ For Far-Infrared (FIR) Heat Therapy

• Ideal Distance: FIR panels are typically integrated into walls, and you're seated or reclined ~6–12 inches (15–30 cm) from the source.
• FIR is non-visible heat radiation; you don’t need to be as close for it to penetrate 1–2 inches (2.5–5 cm) into muscle and tissue.

 

​💡 Pro Tips

• Target Specific Areas: For joint pain, injury recovery, or post-exercise treatment, aim NIR light directly on the affected area for localized benefits.
• Avoid Clothing: Direct skin exposure is critical — clothing blocks NIR and FIR.
• Limit Eye Exposure: Use protective eyewear for NIR sessions <12 inches away. While FIR poses minimal eye risk, NIR LEDs are powerful.

Physiological Mechanisms: Why Saunas Work
Sauna exposure creates a mild thermal stress, triggering a range of protective and adaptive responses, including:

• Cardiovascular conditioning: Mimics moderate aerobic exercise by raising heart rate and plasma volume (Hussain & Cohen, 2018).
• Heat shock protein (HSP) activation: HSPs repair damaged proteins and enhance cellular resilience (Gryka et al., 2020).
• Improved endothelial function: Via nitric oxide synthesis and vasodilation (Kihara et al., 2002).
• Hormesis: Repeated, low-dose stress exposure enhances the body’s resilience to future stress (Seitz et al., 2021).
• Metabolic benefits: Increases insulin sensitivity and reduces inflammation markers such as CRP (C-reactive protein) (Laukkanen et al., 2015).

 

​Important: Always hydrate before and after. Beginners should start conservatively and build tolerance.
​Scientific Evidence: Health, Performance, Longevity
1. Cardiovascular & Mortality Outcomes
A landmark 20-year Finnish study involving over 2,000 men found that frequent sauna use (4–7x/week) was associated with a 50% lower risk of cardiovascular disease and all-cause mortality compared to once-weekly users (Laukkanen et al., 2015).
2. Brain Health and Neuroprotection
Heat exposure may reduce the risk of dementia and Alzheimer's disease via improved vascular function and reduced oxidative stress (Laukkanen et al., 2017).
3. Performance Recovery
Saunas reduce muscle soreness, enhance muscle repair via HSP (Heat Shock Proteins) activation, and improve parasympathetic nervous system balance post-exercise (Scoon et al., 2007).
4. Hormonal and Stress Modulation
Short-term heat stress increases growth hormone (GH) and modulates cortisol. These responses aid in recovery and tissue regeneration (Kaikkonen et al., 2024).
 
Contrast Therapy: Sauna + Cold
Combining sauna with cold immersion or showers — known as contrast therapy — creates vascular pumping effects, enhances muscle recovery, and improves mood through dopamine and norepinephrine release.
Durability Recommended Contrast Protocol

• 15 minutes in dry sauna (90°C / 194°F)
• 30–60 seconds in cold plunge or cold shower (10–15°C / 50–59°F)
• Repeat for 2–3 rounds
• End on cold for muscle recovery, or on warm for relaxation

Contrast therapy has been shown to increase mitochondrial biogenesis, enhance HSPs, and reduce delayed onset muscle soreness (DOMS) (Allan & Mawhinney, 2023).

​Protocols by Goal
✅ Protocol A: General Health and Cardiovascular Longevity

• Frequency: 3–5x per week
• Type: Traditional dry sauna or infrared
• Temp: 80–90°C / 176–194°F (dry) or 55–65°C / 131–149°F (infrared)
• Duration: 15–20 minutes
• Follow with hydration and light stretching
• Benefits: Reduced all-cause mortality, lower blood pressure, improved endothelial health

Evidence: Laukkanen et al. (2015); Seitz et al. (2021)
🏋️‍♂️ Protocol B: Athletic Recovery

• Frequency: Post-training 2–3x/week
• Type: Infrared or traditional dry sauna
• Temp: Infrared (55–60°C / 131–140°F); 80–90°C / 176–194°F (dry)
• Duration: 20–25 minutes, split into two 10–12 min bouts
• Optional: Add contrast therapy (1 min cold)
• Follow-up: Protein-rich meal or recovery shake

Benefits: Muscle recovery, reduced inflammation, enhanced blood flow
Evidence: Gryka et al. (2020); Kaikkonen et al. (2024)
 
🧬 Protocol C: Longevity and Stress Resilience

• Frequency: 4–6x/week
• Type: Alternate dry and infrared
• Temp: Infrared (55–60°C / 131–140°F); 80–90°C / 176–194°F (dry)
• Duration: 25–30 minutes, progressive over time
• Incorporate breathwork or mindfulness
• End with a cool rinse

Mechanism: Hormetic stress + HSPs + improved heart rate variability (HRV)
Evidence: Laukkanen et al. (2018); Seitz et al. (2021); Zaccardi et al. (2024)

Safety Considerations

• Stay hydrated — dehydration risk increases with high sweat rates
• Avoid alcohol before sauna
• Individuals with cardiovascular conditions should consult a physician
• Pregnant individuals should avoid high heat exposure
• Start with lower temperatures and shorter durations
• Always check with your healthcare provider before starting a sauna protocol

Summary
Sauna use is one of the most accessible and scientifically validated lifestyle practices for improving cardiovascular function, metabolic health, neurological resilience, and overall longevity. Whether you’re an athlete seeking faster recovery or a longevity enthusiast pursuing healthier aging, sauna bathing offers a potent, low-risk tool — when used intentionally.
When combined with cold therapy, nutrient timing, and hydration strategies, the impact becomes even more profound. What was once a cultural ritual is now a foundational element of modern healthspan optimization.
 
References
Allan, A., & Mawhinney, C. (2023). Post-exercise cooling lowers skeletal muscle inflammation and damage: Evidence from recent physiological models. Journal of Physiology, 601(10), 2345–2361. https://doi.org/10.1113/JP284293

Gryka, D., Pilch, W., & Szarek, M. (2020). Thermoregulatory and cardiovascular responses to Finnish sauna bathing in healthy men. International Journal of Environmental Research and Public Health, 17(12), 4391. https://doi.org/10.3390/ijerph17124391

Hussain, J. N., & Cohen, M. M. (2018). Clinical effects of regular dry sauna bathing: A systematic review. Evidence-Based Complementary and Alternative Medicine, 2018, 1857413. https://doi.org/10.1155/2018/1857413

Kaikkonen, P., et al. (2024). Acute hormonal responses to heat exposure in trained men: implications for athletic recovery. European Journal of Applied Physiology, 124, 575–588. https://doi.org/10.1007/s00421-024-05642-9

Kihara, T., et al. (2002). Repeated sauna treatment improves vascular endothelial and cardiac function in patients with chronic heart failure. Journal of the American College of Cardiology, 39(5), 754–759. https://doi.org/10.1016/S0735-1097(01)01713-1

Laukkanen, T., Kunutsor, S., Zaccardi, F., & Laukkanen, J. A. (2015). Sauna bathing is associated with reduced cardiovascular and all-cause mortality in middle-aged Finnish men. JAMA Internal Medicine, 175(4), 542–548. https://doi.org/10.1001/jamainternmed.2014.8187

Laukkanen, T., Laukkanen, J. A., & Kunutsor, S. (2018). Cardiovascular and other health benefits of sauna bathing: A review of the evidence. Mayo Clinic Proceedings, 93(8), 1111–1121. https://doi.org/10.1016/j.mayocp.2018.04.008

Seitz, J., Reimers, A. K., & Wichert, R. (2021). Sauna bathing as a health promotion practice: A review on the health effects of regular sauna bathing. Medical Research Archives, 9(6). https://esmed.org/MRA/mra/article/view/3965

Scoon, G. S., Hopkins, W. G., Mayhew, S., & Cotter, J. D. (2007). Effect of post-exercise sauna bathing on endurance performance. European Journal of Applied Physiology, 101(6), 659–667. https://doi.org/10.1007/s00421-007-0548-y

​Zaccardi, F., Laukkanen, T., & Laukkanen, J. A. (2024). Long-term sauna use and mortality: Expanded follow-up from the Kuopio Ischaemic Heart Disease Risk Factor Study. Scandinavian Journal of Medicine & Science in Sports. https://dialnet.unirioja.es/servlet/articulo?codigo=9704407