Sauna & Contrast · NuShape × Soho House

The Sauna
& Contrast

Heat shock proteins triggered by regular sauna use are among the most powerful longevity signals available to the human body — repairing cellular damage that quietly accumulates with every passing year. The sauna is one of the oldest medicines in existence. The science has finally caught up.

Jessica Charles

Founder · NuShape

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Three to four sauna sessions a week is associated with a 40% reduction in cardiovascular mortality — in Finnish research following over two thousand men for twenty years. Not a supplement. Not a device. Sitting in heat, the way humans always have.

The Science

What Heat Does to the Body

The sauna works through four primary mechanisms — each operating independently, meaning any single session is doing multiple things at once. Tap each to go deeper.

Heat Shock Proteins

The cellular repair signal

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When core body temperature rises above 38.5°C, cells produce heat shock proteins (HSPs) — molecular chaperones that fold and repair damaged proteins before they accumulate into misfolded aggregates associated with ageing and neurodegeneration. HSP70 and HSP90 are among the most studied. They are the body's own quality-control machinery, activated by the same signal your ancestors received from fire and hot springs.

Growth Hormone

Up to 16-fold in extended sessions

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Sauna creates a profound growth hormone surge — one of the largest achievable without pharmaceutical intervention. Studies have recorded GH increases of up to 16-fold in sessions of 1–2 hours at 80°C+. GH is essential for muscle preservation, fat metabolism, skin integrity, and cellular repair — and declines significantly with age. The sauna is one of the few accessible tools that meaningfully engages this pathway.

Cardiovascular Health

Heart rate equivalent to moderate exercise

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A Finnish cohort study following 2,315 men over 20 years found sauna use 4–7 times per week was associated with 40% lower cardiovascular mortality. The cardiovascular demand — heart rate elevation, vasodilation, increased cardiac output — produces adaptations comparable to moderate aerobic exercise, making it particularly valuable for those with limited mobility or injury.

BDNF

The brain's growth factor

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Heat stress increases BDNF — brain-derived neurotrophic factor — the primary growth factor for neurons, synapse formation, and cognitive resilience. Often called Miracle-Gro for the brain, BDNF supports learning, memory, and mood and declines with age, chronic stress, and sedentary living. Sauna is one of the most accessible evidence-supported BDNF stimulators available.

40%

Lower cardiovascular mortality at 4–7× weekly

16×

Growth hormone increase in extended sessions

80°C

Minimum for heat shock protein activation

The Mechanism

Vasoconstriction, Vasodilation — The Cardiovascular Pump

Understanding why contrast therapy works requires understanding what heat and cold each do to blood vessels — and why alternating them creates an effect greater than either alone.

Blood Vessel Response — Heat vs Cold

⬆ Sauna · Heat

Vasodilation

Blood vessels relax and widen. Peripheral blood flow increases dramatically. More blood reaches skin and muscle tissue. Core temperature rises. Metabolic waste accumulates in peripheral tissue.

⬇ Cold Plunge

Vasoconstriction

Blood vessels rapidly contract. Peripheral blood is pushed back to the core. Metabolic waste is cleared from peripheral tissue. On rebound, fresh oxygenated blood floods back in.

The cardiovascular pump effect: Alternating between vasodilation (sauna) and vasoconstriction (cold) forces blood back and forth through the peripheral circulatory system — clearing metabolic waste and flooding tissue with fresh oxygenated blood on each cycle. This is significantly more powerful than either therapy alone, and is why the order matters.

III

The Protocol

Sauna First. Cold After.

The order is specific and matters physiologically. The sauna opens blood vessels and drives heat deep into tissue. Cold causes rapid vasoconstriction — pushing peripheral blood back to the core, clearing metabolic waste, and driving fresh oxygenated blood on rebound.

The Contrast Sequence

Heat

15–20 minutes · 80°C minimum

The Sauna

Let the body heat deeply — not just the skin. Core temperature needs to rise measurably above 38.5°C for heat shock protein activation. The discomfort in the last few minutes is where much of the adaptation happens. Hydrate before entering.

Cold

2–3 minutes · 10–15°C

The Cold Plunge

Slow nasal exhale on entry — this is your primary tool for managing the shock response. The instinct is to gasp and breathe rapidly; resisting it activates the parasympathetic system within seconds. Full body immersion for maximum vasoconstriction.

Rest

5 minutes · Return to room temperature

The Rebound

The rebound phase — as the body warms — is where much of the cardiovascular adaptation happens. Fresh oxygenated blood floods peripheral tissue as vessels re-dilate. This phase is often skipped; it shouldn't be.

Repeat

1–2 more rounds if desired

End Cold for Energy · End Warm for Sleep

Ending cold drives the norepinephrine surge most people associate with contrast therapy. Ending warm softens the alerting effect — useful when the goal is sleep or wind-down. Both are valid choices depending on the time of day.

The Cold Plunge — What's Actually Happening

Cold water immersion triggers a significant increase in norepinephrine — driving focus, alertness, and mood elevation that lasts 3–4 hours. It also produces a sustained dopamine elevation, distinct from the crash-and-seek pattern of digital dopamine. The key insight from research by Dr. Susanna Søberg at the University of Copenhagen: deliberate cold exposure is one of the few reliable ways to produce a sustained neurochemical state shift without substance, device, or stimulant.

200–300%

Norepinephrine increase from cold immersion

3–4hrs

Duration of mood and focus elevation

30sec

Minimum for meaningful neurochemical response

Questions Worth Asking

The FAQ — Answered Honestly

What if I do red light before contrast, not after?

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Red light is ideally used after contrast rather than before. Heat and cold do the primary physiological work first. Adding red light after means supporting recovery in a system that has already been stimulated — where enhanced mitochondrial ATP production and tissue repair are most useful. Red light before isn't harmful — it still works. After is simply the more logical order if you're stacking deliberately.

Red light before is fine. After is better sequencing.

What about taking glutathione before the sauna?

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A reasonable practice. Heat temporarily increases oxidative stress — the same mechanism that triggers adaptation also produces a brief reactive oxygen species spike. Glutathione buffers oxidative stress at the cellular level. Taking liposomal glutathione (or its precursors — NAC and glycine) before a session may soften that oxidative load while still allowing heat shock and hormetic adaptation to occur. Worth trying if you have access to quality glutathione.

In the category of thoughtful stacking rather than essential preparation.

I can only last 30 seconds in the cold — how much benefit am I losing?

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Less than you'd think. The norepinephrine response begins within the first seconds of entry — 30 seconds still triggers a meaningful neurochemical response. You're not getting the full benefit of a 2–3 minute immersion, but the benefit is not zero. The gasping reflex, the initial shock, the decision to stay — all of that is the nervous system being trained.

Start where you are. 30 seconds consistently beats 2 minutes occasionally.

How should I breathe in the plunge?

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The slow nasal exhale is your primary tool. When cold water hits, the instinct is to gasp and breathe rapidly — this activates the sympathetic nervous system further and makes the experience harder. A slow, controlled nasal exhale activates the parasympathetic system and genuinely makes the cold more manageable within seconds. Enter slowly, focus immediately on one long nasal exhale. Let the exhale be the anchor.

One slow nasal exhale. That's it. It works every time.

Do I have to end with cold?

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Ending cold is ideal when the goal is energy and post-contrast clarity. But it isn't a rule. If you're using contrast therapy close to bed and want to wind down, ending warm softens the alerting effect and eases the body toward rest. If you have a cardiovascular condition, always follow your practitioner's guidance.

End cold for energy. End warm for sleep. Both are valid.

By Goal

How to Use It

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General longevity · 15–20 min · 80–90°C

3–4 sessions per week for cardiovascular benefit. Core temperature needs to rise measurably — a warm room is not the same as proper sauna temperature. The discomfort in the last few minutes is where much of the adaptation happens.

🏃

Athletic recovery · Contrast protocol

The cardiovascular pump clears inflammatory mediators from muscle tissue. Best used on rest days or after cardio — cold immediately post-strength training may blunt muscle protein synthesis if hypertrophy is the primary goal.

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Sleep improvement · 20 min · 1–2 hrs before bed

The body's core temperature drops after leaving the sauna — mirroring and amplifying the temperature drop needed for sleep onset. One of the most reliable sleep-improvement protocols available, and one of the most overlooked. End warm, not cold, for this application.

The sauna and the plunge have been part of human life for thousands of years — in Finland, in Japan, in Rome, in the hammams of the Middle East. The body has always known how to respond to heat and cold. We are simply remembering how to offer it the opportunity.

NuShape × Soho House · nushape.com · SOHOIBIZA

The Devices in This Room

Cellf · Full Body · Red Light + PEMF + Far Infrared

Multi-Therapy Mat

Includes far infrared — a gentler, penetrating heat. Stack with sauna protocol.

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