Sweating it out at the sauna may have some health benefits, but not all claims are accurate

NEW YORK – These days, the 120 lockers at the Russian and Turkish Baths in the New York City East Village neighbourhood fill up fast on weekends and holidays.

On New Year’s Day, each of the five sauna and steam rooms was clogged with damp 20- and 30-somethings, some stepping over one another to dump buckets of water on their heads in close to 90 deg C heat.

After a pandemic lull, it is boom time again for the 131-year-old institution. In 2022, business was up by about 20 per cent from its best years in the 2010s, said Mr Dmitry Shapiro, a general manager at the bathhouse.

Bathhouse, a spa in Williamsburg, saw admissions rise by 50 per cent in 2022, compared with 2021, a representative said.

There is not much data on global or nationwide sauna use, but the market does seem to have revived, driven mainly by users seeking health benefits.

“There’s a movement now,” said Mr Eero Kilpi, president of the North American Sauna Society, who pointed to commercial saunas popping up as well as sales of portable, mobile saunas, which people can put in their backyard or take on a camping trip.

Saunas, steam baths and sweat lodges are baked into cultural traditions for many people across the globe, from Native Americans to Koreans to Scandinavians. And saunas themselves come in different permutations.

For example, Finnish-style saunas are typically built from wood and known for their dry heat, while steam rooms fill with moist vapour, and more modern infrared saunas often use light panels to generate heat.

As saunas become more trendy, companies often promote them with the promise of health benefits such as “detoxification”, heart health and increased metabolism, along with claims that the heat can simulate a workout without the work.

Posts from Bathhouse’s social media accounts suggest its saunas and steam rooms can release toxins, help one recover from a workout and improve circulation. The Red Rocks Spa in Colorado says that saunas can alleviate insomnia and improve mental health.

There is some research that suggests a trip to the sauna may have some health benefits, but you should not believe every claim you hear, said researcher Earric Lee at the University of Jyvaskyla in Finland, who has studied the health effects.

“It’s not like, ‘Oh, instead of going for my 45-minute run, I’m going to sit in the sauna for 45 minutes,’’’ he said.

Heat for the heart

Although several studies point to the potential benefits of saunas, some of the most prominent research focuses on data from men in Eastern Finland, as part of an ongoing study on risk factors for heart disease.

Observational studies have found intriguing links between regular Finnish-style sauna bathing and lower risks of cardiovascular issues and inflammation, although the studies cannot definitively prove causation and focus on a specific slice of the population (middle-aged and older Finnish men).

Still, the findings suggest that saunas may help improve cardiovascular function, said Associate Professor Setor Kunutsor at the University of Leicester in England, who has been involved in some of these studies.

That may be because, generally speaking, short bouts of intense heat stress the heart in beneficial ways – and strengthen the cardiovascular system over time, he added.

When people are exposed to extreme heat, their hearts pump faster, circulating more blood through the body to cool them down as it would during exercise, said Dr Daniel Gagnon, a researcher at the Montreal Heart Institute. He has also studied the potential cardiovascular impact of heat therapy.

This could explain why regular sauna use has been tied to lower rates of cardiovascular calamities, he added, but scientists have not definitively proved that saunas themselves can be protective.

“So far, we’re really missing the link to say, ‘Yes, for sure, it does something,’” he said. But the heart’s response to heat might mimic mild exercise, he said, perhaps like a light ride on a stationary bike.

“We know that the more you work a muscle, the better a shape it’s in, and the longer it lasts,” said Dr Rita Redberg, a cardiologist at the University of California, San Francisco.

People with heart conditions, such as angina or congestive heart failure, should speak to a doctor before going to a sauna, said Dr Melinda Ring, director of integrative medicine at Northwestern Medicine.

Pregnant women should also consult their physician. And if you are already at risk of getting dehydrated – for example, if you are intoxicated – you should also steer clear of the sauna, she advised.

Many claims, not much evidence

Some spa companies advertise the illusion of a sauna “detox” – the idea that sitting in the heat or steam can leach chemicals from your body.

“There’s this image of ‘All the sweat is going to carry these toxins out,’” said Dr Ring. “That’s really not how it works.”

It is not clear that sauna therapy can lower overall toxin loads in the body, she added.

Although some sauna companies claim that sweating can boost immunity, there is no robust evidence suggesting that a sauna, on its own, will make you more resistant to illness, Dr Gagnon said.

But saunas do reduce stress levels in some people, Prof Kunutsor said, which can benefit the immune system.

And the idea that saunas can make someone magically shed kilos is also false, researcher Lee said. But the most effective time to hop in a sauna may be after a workout, he added, as the heat may be able to amplify the cardiovascular perks of exercise.

He said the “jury’s out” on the long-term benefits of sauna use without exercise. And although saunas may help to make muscles more pliable, potentially alleviating aches, he said, there is no convincing evidence that a post-workout sweat can prevent injuries either.

As promising as some of the research around saunas is, he said, without more studies, it is not clear which claims about the health perks of saunas are accurate, and which are exaggerated.

“I do find a lot of hogwash – a lot of charlatans,” he said. NYTIMES