There is a moment in a good sauna — usually around the fifteen-minute mark, when the heat has fully permeated your muscles and the outside world has become entirely abstract — where you stop thinking about whether this is good for you. You simply know it is. Finns have lived with this certainty for thousands of years. Now, finally, the science is catching up.
The research into sauna health benefits has accelerated dramatically in the last decade, and what is emerging is not a modest wellness story but something rather more striking: regular sauna use appears to reduce the risk of cardiovascular disease, lower rates of dementia, improve mental health, support athletic recovery, and extend healthy lifespan. The mechanisms are increasingly well understood. And the evidence base, once thin, is now substantial.
The Finnish Evidence: Cardiovascular Health and Longevity
The most comprehensive body of sauna research comes from Finland, where the practice is so embedded in daily life that the country has more saunas than cars. The landmark study — the KIHD cohort study led by Professor Jari Laukkanen at the University of Eastern Finland — followed over 2,300 middle-aged Finnish men for more than twenty years. The results were remarkable.
Men who used the sauna four to seven times per week had a 40% lower risk of all-cause mortality compared to those who used it only once weekly. Cardiovascular disease mortality was reduced by 50%. Sudden cardiac death risk fell by 63%. These are not marginal improvements — these are reductions that rival the benefits of regular aerobic exercise. Subsequent analyses from the same cohort found similar protective associations for stroke, hypertension, and neurocognitive disease including dementia and Alzheimer's.
The key question, of course, is mechanism. How does sitting in a hot room protect you from dying? The answer lies in what the heat actually does to the body.
Heat Shock Proteins and Cellular Repair
Dr. Rhonda Patrick, a biochemist who has dedicated considerable research effort to understanding the science of thermal stress, has done more than perhaps anyone to bring heat shock proteins (HSPs) to public attention. When body temperature rises significantly — as it does in a sauna — cells experience mild stress. The response to this stress is the production of heat shock proteins, particularly HSP70 and HSP90.
Heat shock proteins act as molecular chaperones. They repair damaged proteins, prevent protein aggregation (the misfolded protein clumping that is implicated in neurodegenerative diseases like Alzheimer's and Parkinson's), and support cellular resilience. Regular sauna use, Patrick has argued, essentially exercises the cellular repair machinery — keeping it primed and active in ways that cold and sedentary conditions do not.
The implications are significant. Protein misfolding is a hallmark of ageing at the cellular level. Anything that consistently stimulates the systems that clear damaged proteins has genuine anti-ageing potential. This is not speculative: the mechanisms are well characterised in the scientific literature, and the connection to longevity outcomes seen in epidemiological studies like Laukkanen's is plausible and compelling.
Growth Hormone, BDNF, and the Brain
Dr. Andrew Huberman, the Stanford neuroscientist and host of the Huberman Lab podcast, has highlighted several other mechanisms by which sauna benefits the body and brain. Among the most dramatic: growth hormone release.
A study published in the journal Clinical Endocrinology found that sauna exposure — particularly when combined with a brief cold immersion afterwards — can trigger growth hormone release of up to sixteen times baseline levels. Growth hormone is critical for muscle repair, fat metabolism, and tissue regeneration. The combination of heat stress followed by cold exposure (contrast therapy) appears to maximise this hormonal response.
Huberman has also drawn attention to the sauna's effects on brain-derived neurotrophic factor (BDNF), sometimes called "Miracle-Gro for the brain." BDNF promotes the growth of new neurons, supports synaptic plasticity, and protects against cognitive decline. Heat stress is one of the most reliable non-pharmacological stimulators of BDNF, which is part of why regular sauna users report improvements in mood, focus, and mental clarity that go beyond simple relaxation.
The mental health dimension of sauna use is increasingly well documented. A study published in JAMA Internal Medicine found that frequent sauna use was associated with significantly reduced risk of depression and psychosis. The proposed mechanisms include elevated endorphin and dynorphin release (the same pathways activated by intense exercise), along with the social and ritualistic dimensions of sauna culture that foster community and belonging.
Blood Pressure, Heart Rate, and Cardiovascular Conditioning
During a typical fifteen-to-twenty-minute sauna session at 80–100°C, heart rate rises to between 100 and 150 beats per minute — comparable to moderate aerobic exercise. Cardiac output increases substantially. Blood vessels dilate significantly as the body attempts to dissipate heat through the skin. This dilation — and the subsequent constriction that follows cooling — provides a genuine workout for the vascular system.
Regular sauna use has been shown to reduce resting blood pressure, improve endothelial function (the health of blood vessel linings), and lower arterial stiffness. These are not trivial adaptations. Arterial stiffness is one of the strongest predictors of cardiovascular events in middle age. The fact that sauna appears to improve it through a mechanism distinct from exercise means it may be particularly valuable for people who are unable to exercise vigorously — and complementary to exercise for those who can.
Contrast Therapy: The Case for Cold
The evidence is now strong enough that many sports scientists argue the most beneficial protocol is not sauna alone, but sauna combined with cold immersion — what has become known as contrast therapy. The alternation between high heat and cold water (or ice baths) creates a powerful circulatory pump: blood vessels dilate dramatically in the heat, then constrict sharply in the cold. Over repeated cycles, this trains the cardiovascular system, clears metabolic waste products from muscle tissue, and drives the hormonal responses described above.
A 2023 meta-analysis in the European Journal of Applied Physiology found that contrast therapy significantly outperformed passive recovery for reducing delayed-onset muscle soreness (DOMS) in athletes, with effects comparable to active recovery protocols. For anyone serious about physical training, regular contrast therapy sessions are no longer a luxury — they are a rational component of a recovery strategy.
How Long, How Hot? Practical Guidance
The research points towards some practical guidelines for getting the most from sauna sessions. The Laukkanen studies used sessions of around fifteen to twenty minutes at temperatures of 79°C or above. The cardiovascular benefits scaled with both frequency and duration — four to seven sessions per week produced better outcomes than one or two. For most people starting out, two to three sessions of fifteen minutes at 80–90°C per week is a sensible entry point.
Hydration matters significantly. A twenty-minute sauna session can produce up to a litre of sweat. Drinking half a litre of water before your session and rehydrating thoroughly afterwards is essential, particularly if you plan to follow with cold water immersion.
The oft-repeated advice to listen to your body is particularly relevant here. Exit the sauna if you feel dizzy, nauseous, or experience chest discomfort. Those with cardiovascular conditions, those who are pregnant, or those taking medications that affect blood pressure should consult a doctor before beginning regular sauna use.
Where to Experience It in the UK and Ireland
The good news for anyone convinced by the science is that access to quality sauna facilities in Ireland and the UK has never been better.
In London, ARC Wellness in Canary Wharf offers the city's largest communal sauna — a circular space for sixty-five people with cold plunge baths and a curated sound system. Brockwell Lido Sauna in Herne Hill brings the Finnish outdoor experience to South London, adjacent to the historic lido. For those who want an authentic steam room tradition, York Hall Spa in Bethnal Green has been a working-class wellness institution since 1929. The Community Sauna Baths network — with sites across Hackney Wick, Peckham, Stratford, Camberwell and now beyond — has done more than any other operator to democratise access, with sessions from under £10.
In Ireland, The Sea Sauna in Donabate offers the quintessential Irish coastal experience — a wood-fired sauna steps from the sea, where the cold Atlantic is your plunge pool. Further north, Riverbank Sauna in Palmerstown brings community-focused bathing to the city outskirts. For a world-class indoor spa experience, Thermae Bath Spa in Bath — England's only natural hot springs spa — offers rooftop bathing at 40°C with views of the Georgian city.
For those drawn to Scandinavian origins, Löyly in Helsinki — a public sauna with restaurant and sea swimming directly from the terrace — represents the gold standard of what contemporary sauna culture can aspire to be. If you make one international wellness trip this year, Löyly is a strong candidate.
The Simplest Medicine
It would be easy to over-medicalise what is, at its core, a very simple practice: getting hot, cooling down, resting, and doing it again. The science matters — not because it validates something that needed validating, but because it helps us understand why an ancient human ritual continues to feel so profoundly restorative.
The Finns were not wrong. They built their national identity around a practice that turns out to be genuinely good for the heart, the brain, the muscles, and the mind. That we are only now catching up with the evidence should prompt us not to wait any longer to act on it.
Find every sauna, cold plunge, and thermal spa in Ireland and the UK — with real reviews, prices, hours, and transport information — at thermae.app. Whether you are a sauna veteran or stepping into your first session this week, the directory is there to help you find the right venue for where you are and what you need.