People can die simply because they've given up, life has beaten them and they feel defeat is inescapable, according to new research.
The study, by Dr John Leach, a senior research fellow at the University of Portsmouth, is the first to describe the clinical markers for 'give-up-itis', a term used to describe what is known medically as psychogenic death.
The five stages of give-up-itis are:
In concentration camps, people who reached this stage were often known to be near death by fellow prisoners when they took out a hidden cigarette and began smoking it. Cigarettes were highly valuable in the camps and could be traded for important things such as food.
Dr Leach said: "When a prisoner took out a cigarette and lit it, their campmates knew the person had truly given up, had lost faith in their ability to carry on and would soon be dead."