Sauna bookings rebound amid England's fourth heatwave, but experts say they are no shortcut to safety

Some sauna operators in the U.K. say bookings are starting to recover after an early drop as parts of England go through another heatwave.

The industry is getting a bounce back after saunas were claimed to help increase the body's ability to deal with hotter temperatures.

Experts warn that any benefit from repeated heat exposure is about building tolerance over time, not about using a sauna as a same-day answer to extreme temperatures.

What's happening?

According to the Guardian, the U.K. Health Security Agency has put heat health alerts in place across large areas of England during the country's fourth heatwave of the year.

The alerts come in a summer that included the hottest June ever recorded in western Europe.

Nicola Pegues, head of operations at Community Sauna Baths, a not-for-profit that runs outdoor sauna sites and cold plunges, said demand fell when temperatures first climbed.

But Pegues said reservations have begun to rebound, and that moving between hot and cold can feel refreshing. "But now we're seeing bookings come back," she said. "You get real relief out of it actually."

Researchers say there is some science behind the idea of heat training.

Prof. Jari Laukkanen, a cardiologist at the University of Eastern Finland, said the body can become better able to handle later heat exposure when it is repeatedly exposed to heat over time.

"In other words, regular heat exposure may help the body regulate temperature more efficiently," he said.

Why does it matter?

Experts say there is an important difference between becoming acclimated to heat and staying safe during a dangerous hot spell. The research is about conditioning the body in advance over days or weeks, not chasing a remedy once temperatures are already extreme.

Dr. Jessica Mee of the University of Worcester, who is recruiting participants to study hot water immersion and heat response, said regular exposure to heat may also shape how people respond behaviorally.

"People who are accustomed to heat pace themselves more sensibly, hydrate more consistently and recognise their own warning signs earlier," she said.

However, those adaptations do not happen equally for everyone.

Dr. Heather Massey, an expert in extreme environments and physiology at the University of Portsmouth, said the changes depend heavily on the body's ability to increase sweating and send more blood to the skin.

During periods of extreme heat, official alerts, hydration, rest, and checking on vulnerable people matter most.

What can I do?

When heat training is used, it is generally done in a controlled setting for about 40 to 60 minutes a day over at least four to six days.

Without continued exposure, the benefits usually wear off after about a week, although longer training can make them last longer.

Still, that is not a reason to begin lengthy sauna sessions or hot baths during a heat alert.

Mee warned that very hot days can add stress to a body that may already be short on sleep, low on fluids, and under cardiovascular strain: "You are stacking one thermal challenge on top of another."

Laukkanen also said that people with an acute illness or fever, unstable angina, a recent heart attack, or uncontrolled low blood pressure should avoid saunas or hot baths until they have been medically assessed or treated.

If you are trying to stay safe in a heatwave, the best steps remain the least glamorous: drink water, take it easy during the peak heat of the day, cool your home when possible, and pay close attention to public health advice.

As Laukkanen put it, "There is currently limited evidence that going to a sauna during a heatwave itself protects people from heat-related illness or other conditions."

Mee put it more bluntly: "Heat acclimation is a preparation strategy for the mild months, not a coping strategy for the hottest day of the year."

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