A new medical study has concluded that it is possible for an individual to have 'awareness', even after the brain has shut down, the Telegraph reports.

The latest evidence suggests that some kind of consciousness can continue for minutes after a person is clinically dead, which was previously thought impossible.

In the biggest ever scientific study into near-death and out-of-body experiences, researchers at the University of Southampton spent four years examining more than 2,000 patients who suffered cardiac arrest in hospital.

Almost 40 per cent of those who survived – 140 out of 330 cases – said they experienced some kind of 'awareness' before they were resuscitated – during a time when their hearts weren't beating and they were clinically dead.

"The evidence thus far suggests that in the first few minutes after death, consciousness is not annihilated. Whether it fades away afterwards, we do not know, but right after death, consciousness is not lost," said Dr Sam Parnia, who led the study.

One 57-year-old man who took part in the research described the noises made by medical equipment and the actions of hospital staff in detail, all of which took place during a three minute period in which he was technically dead.

He said he was able to watch his own resuscitation from the corner of the room, having 'left' his body, and his description of what took place matched up with the reality.

"We know the brain can't function when the heart has stopped beating, but in this case, conscious awareness appears to have continued for up to three minutes into the period when the heart wasn't beating, even though the brain typically shuts down within 20-30 seconds after the heart has stopped," Dr Parnia told the Telegraph.

"The man described everything that had happened in the room, but importantly, he heard two bleeps from a machine that makes a noise at three minute intervals. So we could time how long the experienced lasted for.

"He seemed very credible and everything that he said had happened to him had actually happened."

Not all of the experiences patients shared were positive, however. While 20 per cent described a peaceful sensation and others remembered seeing a bright light, some recalled a sense of fear, persecution, or feeling like they were being submerged in water.

According to Dr Parnia, it's likely that many more people have "vivid" near-death experiences than are able to recall them after the event.

"Estimates have suggested that millions of people have had vivid experiences in relation to death but the scientific evidence has been ambiguous at best," he explained.

"Many people have assumed that these were hallucinations or illusions but they do seem to corresponded to actual events. And a higher proportion of people may have vivid death experiences, but do not recall them due to the effects of brain injury or sedative drugs on memory circuits."

Dr Parnia added: "Contrary to perception, death is not a specific moment but a potentially reversible process that occurs after any severe illness or accident causes the heart, lungs and brain to cease functioning.

"Clearly, the recalled experience surrounding death now merits further genuine investigation without prejudice."