Unbelievable.. See what happen when you're dead that we Don't know

Actress Ellen Page in a scene from the remake of the film Flatliners

When you die you know you're dead because the brain keeps functioning and you know what's happening around you, chilling new research suggsts.

Medical experts have long debated what happens when a person dies, with
anecdotal evidence of bright lights or sensations, and films such as Flatliners exploring the unknown.

But a new study suggests a person's consciousness keeps working after their heart stops beating and their body movements fail.

Cardiac arrest survivors were aware of what was going on around them while they were 'dead' - including seeing doctors trying to save them or hearing conversations - before being 'brought back to life', the study revealed.

It means that a person may even hear their time of death being announced by medics as they are essentially 'trapped' inside their body with brain function.

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Dr Sam Parnia is studying consciousness after death and examining cardiac arrest cases in Europe and the US.

He said anecdotal evidence has found that people in the first phase of death may still experience some form of consciousness.

The expert told LiveScience that people who have survived cardiac arrest later accurately described what was happening around them after their hearts stopped beating.

He said: "They'll describe watching doctors and nurses working, they'll describe having awareness of full conversations, of visual things that were going on, that would otherwise not be known to them."

Dr Parnia, of the NYU Langone School of Medicine in New York, said the accounts were verified by doctors and nurses, who were left stunned after learning that the patients remembered the details after being resuscitated.

His study is examining what happens to the brain after a person goes into cardiac arrest - and whether consciousness continues after death and for how long - to improve the quality of resuscitation and prevent brain injuries while restarting the heart.

Unlike the plot in Flatliners, however, when a person is resuscitated they don't return with a "magical enhancement" of their memories, said Dr Parnia.