London: Social media often presents saunas and cold plunges as near-miracle cures, claiming they can boost immunity, burn fat, and resolve a wide range of physical and mental health issues, from joint pain to low mood. However, experts say the reality is far more nuanced.
Dr. Heather Massey, Associate Professor of extreme environments and physiology at the University of Portsmouth, says that while many people strongly believe in the benefits of hot and cold exposure, there is not yet enough scientific evidence to confirm that these practices are categorically good for long-term health.
Dr. Massey explains that the human body is remarkably effective at regulating its core temperature, which usually remains between about 36.5°C and 37°C. In modern life, most people rarely challenge this system, as they spend long periods in heated or air-conditioned environments.
According to the Associate Professor, deliberately heating or cooling the body creates a small stress, which may trigger adaptive or protective responses. This theory underpins the growing popularity of saunas, which are now a common feature in gyms and spas and are often busy.
For some, using the sauna is a reward after exercise, while for others it is the main reason for visiting. Many regular users are convinced that around 15 minutes of intense heat delivers noticeable benefits for both body and mind. Dr. Massey acknowledges that sauna use can feel beneficial, noting that people often feel looser, freer, and more mobile, with aches and pains easing temporarily after a session.
The Associate Professor adds that while there is clearly some benefit, it remains unclear whether the effects are long-term health improvements or primarily psychological.
Referring to a recent study in which participants were repeatedly immersed in hot tubs, Massey noted that researchers observed changes in insulin levels and blood pressure, suggesting that heating the body may have potential benefits for people living with lifelong conditions.
Despite this, Dr. Massey urges caution when it comes to bold health claims, emphasising that robust scientific evidence is still limited. The Associate Professor notes that there has never been a comprehensive, controlled sauna trial. While she suspects future research may identify clear benefits, she says the science is not yet conclusive.
Saunas or cold-swims?
For now, the Associate Professor advises people to enjoy saunas for the way they make them feel, rather than viewing them as a guaranteed shortcut to better health. Massey also recommends easing into sauna or hot tub use gradually and consulting a GP first, particularly for those with underlying health conditions or for pregnant women.
At the other end of the spectrum, cold-water swimming has also grown rapidly in popularity, with early-morning group dips becoming a familiar sight at beaches, lakes, and rivers. Dr. Massey, who has swum the English Channel and competed in world ice-swimming championships, swims in cold water once a week but limits her exposure to just a couple of minutes.
The Associate Professor explains that the initial immersion triggers an involuntary gasp and rapid breathing, with heart rate and blood pressure rising sharply and stress hormones such as cortisol and adrenaline surging.
This shock response peaks at around 30 seconds before dropping away quickly. With repeated short exposures, the intensity of this response can be reduced by approximately 50 percent.
As with sauna use, Dr. Massey says it is difficult to determine whether the benefits of cold-water swimming come from the cold itself or from the wider experience. Cold swims are usually done outdoors, often with others, making them activities that combine nature, physical movement, and social connection.
For Dr. Massey, the key factor is enjoyment rather than temperature. She points out that people who regularly take part in Parkrun often describe the same sense of wellbeing or ‘buzz’ as cold-water swimmers.
What matters most is finding an activity that you enjoy, can do consistently, and ideally share with others, as building friendships around activities can help reduce psychological stress.
That activity could be anything, from gardening and birdwatching to joining a choir or simply walking with friends. While saunas and cold-water swimming may not be essential for good health, Dr Massey concludes that they can still offer positive benefits when they are enjoyable and part of a balanced lifestyle.
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