Hot topic: Why ‘slow motion’ saunas are becoming the new cold swimming

It’s Sunday morning, and as the fashionable folk of Kings Cross go about their business, I’m watching them from a pop-up sauna, sweating in my swimsuit and gnome-like sauna hat. 

Moments later my friends and I plunge into an ice bath, rush back into the sauna, and repeat. The outdoor urban setting is comical, but the combination of heat, cold, and friendly chats is exhilarating. 

The “slow motion sauna” is the brainchild of DJ and Bestival founder-turned sauna-evangelist, Rob da Bank, and his wife Josie. He first opened the mobile Lithuanian wood-fired sauna last summer on Freshwater Beach near his home on the Isle of Wight. 

“I started it as a hobby, but it became a bit of an addiction. Then Kings Cross got in touch about their Mind Your Brain campaign. Bringing some warmth and wellness to Londoners in this grey month seemed like a no-brainer,” he says. 

The sauna, which is in London until mid-February, is the latest manifestation of a blossoming craze for heat. From beachside converted horse boxes to forest retreats to hip urban hangouts, saunas are popping up everywhere.

Gabrielle Reason is the secretary of the British Sauna Society and keeps a register of the new wave of “authentic” steam rooms around the UK as opposed to those found in gyms and spas. 

Last year there were 45 on her books, this year the number has already doubled to 90. In 2018, there was just one “new wave” sauna listed, Beach Box Brighton, a pioneering converted horse box sitting right on the beach.

Katie Bracher was the co-founder of Beach Box Brighton and now runs a sauna in a forest glade in Sussex, Wild Spa at Wo Wo.

“I’d tried a sauna at a festival and then had a dip in a cold lake afterwards, and felt totally reborn, so I was seeking that experience, but it didn’t exist. We started with a horse box for seven people, and now there are four 12-person saunas,” she says.

Beach Box inspired a wave of saunas on wheels, which can be easily started without needing permanent planning permission. #

In 2022 Gabrielle Reason kicked off the urban trend by co-founding the Hackney Wick Community Sauna Baths in east London. “We started small with one day a week, but we quickly sold out and added more days and weekends. Now it operates with seven saunas, six days a week,” she says.  

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Although there have been celebrity sauna-loving trailblazers like David Beckham, Guy Ritchie and David Baddiel, in many ways the growing love for saunas is a natural extension of the craze for cold water swimming. 

“The first people to come are usually the cold water swimmers, they’ve trained their bodies for stress, and heat stress is similar. The combination of hot and cold generates a lovely endorphin rush,” explains Gabrielle Reason. 

It’s also a deeply relaxing, feel-good experience. “Think of it as the new pub,” says Da Bank. “It’s a social place, you don’t have many clothes on yet you don’t feel exposed. You haven’t got your phone and can switch off. I challenge myself a bit with the heat and the ice bath or sea, and afterwards, I feel incredible physically, but also emotionally too – a bit spiritually high.” 

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Science supports many of the advocates’ claims of mental and physical benefits. Much of the latest research comes from Finland where the sauna tradition goes back thousands of years. Studies by Professor Jari Laukkanen of the University of East Finland have shown significant benefits for the heart and the risk of dying from heart-related causes is lower among regular sauna users, as well as reductions in the risk of Alzheimer’s and dementia.

The reason for this is because as you start to heat up in the sauna, your body responds by pumping more blood to your skin to lose heat, and you sweat. As it does this, your heart rate increases to get your blood moving, a bit like when you’re exercising. Under heat stress (and this happens when cold water swimming too), heat shock proteins are stimulated into action and they help to repair damaged cells.

The temperature of saunas is quite subjective. Some people prefer it to be around 75/80C and others prefer a more intense 95C. How long people stay in also varies hugely, but many sauna lovers like to push themselves to stay in as long as they can, measuring their heartbeat to see if they are in a high-intensity zone.  

Since saunas increase our heart rate they also confer some of the benefits of a low-intensity workout, although Tom Cullen, assistant professor in applied physiology of Coventry University, cautions that we can’t yet claim they are a weight loss tool.  

He is most excited by evidence that shows saunas help reduce chronic inflammation over time, by stimulating our immune system. “Inflammation is now thought to underpin a host of diseases including heart failure and depression,” he says. 

Studies from the USA by psychiatrist Charles Raison have also demonstrated that this reduction in chronic inflammation is an effective treatment for depression. 

Anecdotally, regular sauna users report that it’s good for their stress levels and improves sleep. “Saunas cause a rush of beta-endorphins, and these have a group bonding effect, making us feel connected and like we belong. People who report strong feelings of group belonging have far greater wellbeing,” says Gabrielle Reason.

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 At the Hackney Wick Sauna, Reason heard many stories of health transformations. People reported that it had helped their arthritis, but for most, the appeal is that it’s a fun social experience, where you can come with friends or chat with strangers. “There’s a real camaraderie that brings together all ages in a very bonding way.” 

For her recently published book, Sauna: The Power of Deep Heat, Emma O’Kelly clocked up thousands of miles travelling through Scandinavia and the Baltics to discover the history and cultural importance of a centuries-old tradition. Back in the UK, she is excited by the flourishing UK sauna scene. 

“Because we’re not bound by any tradition we can mix and match, a bit like we do with our food. From Lithuanian and Estonian whisking to Aufguss ceremonies from Germany to grief saunas in Hackney, we are being experimental, and that’s what makes the UK scene so exciting.” 

Emerging from my Kings Cross experience glowing and refreshed, we go for a coffee round the corner, which is nearly the same price as the sauna, a bargain at just £6. That night I slept brilliantly; I’m already planning my next fix. 

Beach Box Brighton

It’s the original mobile sauna and so many have been formed in its mould around the UK. From the horsebox saunas to the events they run, to the gentle feminine energy that makes you feel looked after.

From £12.50 for an hour session 

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Sea Scrub Sauna, Margate

The two saunas face onto a tidal pool where you can plunge, but there's also freshwater cold plunge barrels. There is a new electric sauna and both saunas overlook the famous Margate skyline, and its legendary sunsets.

From £13 for 1 hour

The Bath House, London

A traditional, upscale Russian bath in London’s Belgravia. Expensive, but a transporting hot and steamy experience, coupled with traditional treatments and Russian snacks. You’ll sleep well after a session here. 

From £60 for a 2-hour banya session

Hackney Wick Community Saunas 

Dedicated to bringing affordable saunas and wellness experiences to the Hackney community, the baths have been a hit since they opened in 2022. Located in an old public bath building dating from the 1930s, there are 10 saunas of varying sizes. It’s been so popular that the team have opened a new site in Stratford. 

From £8.50 for 1 hour 

Elie Seaside Sauna - Fife 

Many saunas have popped up in Scotland in beautiful locations and Elie Seaside Sauna is one of the most stunning. Perched on the dunes at Elie Harbour, the sauna is a converted wood-fired horsebox with beautiful views of the sunset. 

From £12 for 1 hour