Hi Friend,

Dry sauna is likely superior to wet sauna.

Dry (Finnish) sauna delivers low-humidity heat, so your skin hits 40°C in minutes while core creeps up only ~1°C. That gradient shunts up to 70% more cardiac output to the skin, mimicking moderate-intensity cardio without moving a muscle.

Enhanced Blood Flow: The heart pumps up to 70% more blood, similar to intense aerobic exercise (zone 3), with 50–70% of this increased flow re-directed to the skin, promoting vasodilation and improved skin circulation.
Increased sweating and detoxification: To maintain a stable core temperature, the skin produces 0.6–1 kg of sweat per hour, facilitating significant detoxification.
Improved heat tolerance: The body becomes better at handling heat, leading to a lower core body temperature (offering metabolic advantages) and an increased capacity for efficient sweating in hotter climates.
Activation of heat-shock proteins: The skin experiences substantial heat shock protein activation, while a modest 1°C increase in core temperature is sufficient to activate these proteins without the risk of hyperthermia.
Longer exposure at higher temperatures: Dry saunas are more tolerable for longer durations and at higher temperatures, allowing users to maximize the benefits at minimal risk.

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Keep calm and sauna on, Bryan

Originally published in Bryan Johnson's Blueprint newsletter (May 28, 2025). This content is for informational purposes only and is not medical advice.

Dry Sauna vs. Wet Sauna: The Hot Truth About Finnish Saunas