For some, hot yoga is the ultimate chill breaker. One popular style, Bikram yoga, is done in a room heated to at least 105⁰ F. Fans say it helps you "sweat out toxins" and achieve deeper poses.

“Bikram yoga was an addiction,” says Tina Chagoury, who practised several times a week for three years before becoming ill. “What makes it addictive is that you can perform three times ...