In a study that noted the findings could lead to new medical and ethical challenges, Canadian doctors in an intensive care unit reported that they had seen "single delta wave bursts persisted following the cessation of both the cardiac rhythm and arterial blood pressure.

Brain activity may continue for more than 10 minutes after the body appears to have died, according to new research.

In the case, doctors confirmed their patient was dead through a range of the normal observations, including the absence of a pulse and unreactive pupils. But tests showed that the patients' brain appeared to keep working – experiencing the same kind of brain waves that are seen during deep sleep.

Only one of the four people studied exhibited the long-lasting and mysterious brain activity, with activity in most patients dying off before their heart stopped beating. But all of their brains behaved different in the minutes after they died – adding further mystery to what happens to them after death.

The findings were published by a team from the University of Western Ontario.