Brian Byrne, a tour manager in Los Angeles, was sipping a cold brew a few years ago when he started feeling clammy. Soon, his symptoms worsened: shallow breathing, a hollow feeling in his chest and a rapid, thumping heartbeat. He went outside to get air. “At that point, I was having racing thoughts, feeling like I was having a heart attack,” he says.

This wasn’t the first time Byrne experienced a caffeine-fuelled panic attack, but it was the most intense. “Drinking that coffee felt like I poured gasoline on a fire that was already smouldering,” he says. For a year after, he didn’t touch the stuff and didn’t have another serious episode.