Scroll through social media and you’d be forgiven for thinking saunas and cold plunges are close to a miracle cure, boosting immunity, burning fat and fixing everything from sore joints to low mood.
But the reality, experts say, is more nuanced.
“There are a lot of people who swear by hot and cold exposure, but we don’t yet have sufficient evidence to say it’s categorically good for you,” says Dr Heather Massey, associate professor of extreme environments and physiology at the University of Portsmouth.
She explains our bodies are “incredible” at keeping core temperature stable, usually between about 36.5C and 37C.
In everyday life, many of us rarely challenge that system, spending long periods in heated or air-conditioned spaces.
Heating or cooling the body creates a small stress, she says, which may trigger adaptive or protective responses.