The science-backed benefits of a wood-fired sauna

A wood-fired sauna is more than heat and ritual. Regular sessions trigger measurable changes in your brain, hormones, blood volume, circulation and even connective tissue. Below is a plain-English tour of what the research says, with quick notes on how to use your sauna to get these benefits.

1) Endorphin release

Short, hot Finnish-style sessions raise circulating beta-endorphins, the body’s natural pain-relieving, mood-boosting peptides. Classic lab work in healthy adults showed significant rises in plasma β-endorphin during intense sauna heat, aligning with the “post-sauna glow” many people report. SpringerLink+1

2) Dopamine increase

Heat stress activates catecholamine pathways. Early human studies in Finnish saunas recorded large increases in plasma noradrenaline and smaller but meaningful changes in other catecholamines that sit upstream of dopamine signalling and arousal. Reviews of sauna neurobiology now summarise these effects as increased dopaminergic tone contributing to alertness and well-being after sessions. PubMed+2europepmc.org+2

3) Norepinephrine surge

This one is robust. Exposure to 80–100 °C can double or more than double circulating norepinephrine, similar to vigorous exercise. That spike sharpens attention, supports mood and modulates pain pathways. 

4) Growth hormone spike

Brief sauna bouts can acutely raise growth hormone, which supports tissue repair and metabolism. In a controlled study, 15 minutes at ~72 °C increased GH from about 2 to 5 µg/L within 30 minutes. Repeated exposures appear to amplify the effect in some protocols. 

5) Heat shock proteins (HSPs)

Sauna-level heating induces heat shock proteins such as HSP70. These chaperone proteins protect cells under stress, assist protein repair and may improve glucose handling. Both passive heating and exercise raise HSP70, and acclimation strengthens this response over time. PMC+1

6) Parasympathetic activation

During the hot phase your heart rate rises, but recovery is where relaxation chemistry shines. Heart-rate-variability studies show a shift toward higher vagal (parasympathetic) activity during the cool-down after a sauna, matching what people feel as deep calm and better sleep. Bristol Research Information

7) Plasma volume expansion

With a handful of sessions your body adapts like it would to training in the heat. The blood’s plasma volume expands, which helps the heart pump more efficiently and stabilises blood pressure during exercise. Small athlete studies show roughly 5–18% expansion within a week of post-exercise sauna use. Reviews confirm plasma-volume expansion is a hallmark of heat acclimation. PMC+1

8) Increased perfusion and “passive cardio”

Heat dilates blood vessels, increases skin blood flow and temporarily lifts heart rate to something like steady-state cardio. In clinical heat-therapy settings this vasodilation lowers vascular resistance and raises cardiac output, one reason regular sauna use is linked with healthier blood-pressure profiles over time.

9) Tissue extensibility and mobility

Warmth changes the viscosity of connective tissues. Systematic reviews in rehabilitation note that heating improves range of movement and tissue extensibility, and may support angiogenesis and strength when used repeatedly alongside training. This matches the real-world experience of easier stretching after a sauna. PMC+1

10) Cytokine modulation

A typical Finnish session acutely raises interleukin-6 (IL-6) and its anti-inflammatory receptor antagonist IL-1RA, without the harmful spikes in TNF-α seen in illness. In depression hyperthermia studies, heat elevated IL-6 in a pattern associated with anti-inflammatory signalling. Over time, this transient “good stress” may help nudge immune balance in a favourable direction. PubMed+1

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What this adds up to

Large cohort studies associate frequent Finnish-style sauna bathing with lower risks of hypertension, fatal cardiovascular events and all-cause mortality. Mechanisms above are the likely reasons. That evidence base is strongest for traditional dry saunas heated to ~80–100 °C.

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How to use your wood-fired sauna for these benefits

• Heat dose
  Aim for 80–95 °C air temperature measured at head height, with comfortable humidity. Start with 3 × 10–15 min bouts separated by cool air or a brief rinse. Acclimate over 2–3 weeks. PMC

• Frequency
  2–4 sessions per week is a practical target for most people. Many of the cardiovascular associations strengthen at 4–7 per week, but benefits appear on fewer. 

• For recovery and mobility
  Use the sauna after training to leverage plasma-volume expansion and connective-tissue pliability. Finish with an unrushed cool-down to engage the parasympathetic system. PMC+2Bristol Research Information+2

• Hydration and electrolytes
  Replace fluids and salt. Plasma-volume expansion depends on both heat exposure and adequate rehydration. PMC

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Safety first

Avoid sauna use if you feel unwell, are dehydrated, pregnant, or have unstable cardiovascular disease. Stand up slowly, limit alcohol, and cool gradually. If you take blood-pressure or psychoactive medicines, check with your GP first. Reviews emphasise that while sauna is generally safe for healthy adults, most trials are small, so common-sense caution matters. PMC