Linda Geddes is a science correspondent for The Guardian. She bravely went out to test a new anxiety treatment in development by researchers at the University of Cambridge. After about five minutes of this, when I'm feeling very calm and I've got the hang of the breathing, suddenly I'm transported into a completely different environment. It's horrible. So where are you now? What’s going on? I'm underground, sat on a chair, I kind of look around me and there's like a few fluorescent light bulbs to either side. And then I look down and see that my hands are strapped to this chair and there's blood on them.I start hearing these sounds