Graham was eventually sent to neurologists Adam Zeman at the University of Exeter, UK, and Steven Laureys at the University of Liège in Belgium — who discovered something remarkable about his condition.

Cases tend to have been reported in patients with mood disorders, psychotic disorders, and depression, and often stem when a part of our brain that recognises faces and emotions cracks.

“What they found was shocking: metabolic activity across large areas of the frontal and parietal brain regions was so low that it resembled that of someone in a vegetative state,” according to New Scientist.

These regions, known as our “default mode network” affect our ability to “recollect the past, to think about ourselves, to create a sense of self and allows us to realise that we are the agent responsible for an action”.

“Graham’s brain function resembles that of someone during anaesthesia or sleep. Seeing this pattern in someone who is awake is quite unique to my knowledge.”

For Ms Wang, after two months living with the condition, “[The delusion] lifted completely without fanfare. There was no beam of light from the heavens; I was just going along and somebody pointed out that I was acting different,” Ms Wang said. “I realised I thought I was alive.”