Sauna and Contrast Therapy in Ireland: Evidence and Safety

Contrast therapy means alternating heat, usually a sauna, with cold, usually a plunge or a dip in the sea. The evidence for saunas is mostly observational, the evidence for the combination is thin, and the combination puts extra demands on the heart. If you have any heart, blood pressure or lung condition, speak to your GP before trying it. Everything below is general information, as of October 2026.

What the research on saunas shows

The most quoted study is a Finnish one by Laukkanen and colleagues, published in JAMA Internal Medicine in 2015. It followed 2,315 men aged 42 to 60 from eastern Finland. Compared with men who used a sauna once a week, those who went two to three times a week had a sudden cardiac death risk that was 22% lower, and those who went four to seven times a week had a risk that was 63% lower, according to a published summary. Longer sessions were also associated with lower risk.

Read that carefully. It is an association in a group of middle-aged Finnish men who grew up with sauna habits, and the authors themselves said further studies were needed to understand the mechanism. It does not show that starting a sauna habit in Ireland will cut your risk of heart problems. People who use saunas often may also differ in fitness, income and health in ways that are hard to separate out.

The American Lung Association takes a similarly measured line, saying little research supports the advantages of saunas. It notes that warm, moist air might loosen mucus and ease breathing for some people with chronic lung disease, but that dry air can make breathing harder and raise the chance of a flare-up for others.

Note who was studied: the Finnish figures come from Finnish men using traditional saunas, not from people moving between heat and cold water, so they say nothing about contrast therapy.

What the research says about combining heat and cold

Plainly: do not do hot-to-cold contrast if you have a heart, blood pressure or lung condition, if you are pregnant, or after drinking alcohol. In those cases a sauna on its own, if your doctor agrees, is a separate question.

No Irish or UK health body page consulted for this article sets out rules for moving between a sauna and cold water. The American Lung Association says that alternating heat and cold is claimed to strengthen the cardiovascular system over time, but that the short-term strain can have serious consequences. That is the key trade-off: any benefit is unproven, while the strain is immediate.

The reason is easy to see. Heat widens blood vessels and raises the heart rate. Cold water narrows blood vessels, raising blood pressure and making the heart work harder, and cold shock can cause rapid, uncontrolled breathing, dizziness or fainting. Doing one straight after the other asks your circulation to swing sharply in both directions.

Who should be cautious

The American Lung Association lists pregnant people, children and older adults, people with high blood pressure, heart conditions or chronic heart or lung disease, and anyone with a respiratory infection (for saunas), as groups who should be cautious or avoid these therapies. It also advises against sauna use after drinking alcohol. For heart conditions, it says most healthcare providers advise against cold plunges.

Our own page on who should not do cold water immersion covers the cold side in more detail, and cold water immersion and medication or conditions explains what to ask a pharmacist or GP.

Practical safety points for a sauna session

• Heat can dehydrate you, causing dizziness or nausea and worsening chronic illness, so drink water before and after.
• For healthy adults, the American Lung Association suggests starting with 5 to 10 minutes and never exceeding 20 minutes. This is a US source, so treat it as a conservative general rule, not an Irish standard.
• Leave if you feel dizzy, nauseous, faint or short of breath, and sit somewhere cool until it passes.
• Avoid alcohol before a session.
• Do not go straight from a hot room into cold water without a pause and a plan. Have someone with you.

Cost and access in Ireland

Prices for saunas vary widely by type, size, installation and running costs, and no sourced Irish price ranges were available for this article, so none are given. For a pay-per-session option, check the current price directly with the operator, ask what is included and whether they take a medical questionnaire or have staff on site. For a home unit, ask installers for a written quote that includes electrical work, ventilation and any planning or building control requirements, and ask your electricity supplier how a new load might affect your bill.

If you are weighing equipment for the cold half of contrast therapy, the cold plunge tub buyer's guide and running costs cover the practical side. For the wider evidence on cold exposure, see health benefits evidence.

A fair summary of the evidence is that a sauna can be a pleasant way to warm up and relax, that heart-health claims rest on observational data, and that mixing it with cold water adds risk without proven extra benefit. Choose it for enjoyment if it suits you medically, and do not rely on it as a health treatment.