In the Victorian Era, people were so afraid of death and yet fascinated by it, that they tried to talk to the dead in seances, had prolonged formal mourning periods, and took photos of their dead for memory keepsakes. They also came up with the concept of cemetery bells that ran a cord into a casket just in case someone was buried when not fully dead.
It happens from time to time. I worked an in ER and one time they pronounced a man dead and about 15 minutes later, when the nurse was sent in to prepare him for the family visit, he spoke. The nurse's scream could be heard throughout the building. This lucky minister who came back from the other side, was good spirited enough to invite the doctors to his family's celebration on the floor when they relocated him to ICU.
There is a case that caught a lot of attention of a 49-year-old grandmother who had a massive heart attack. Paramedics worked on her for 3 hours and finally pronounced her dead for 45 minutes. And, as they prepared to harvest her organs, she made herself known as among the living.
The family had been allowed in to say goodbye when one of them announced she had squeezed their hand and opened her eyes. The nurse said "involuntary" movements were to be expected, but the family demanded she be examined. When the husband told her he loved her and to come back to him, she did just that!
She had no residual brain damage which is unbelievably rare, as lack of oxygen should have caused "anoxic" brain injury. The staff was forced to relearn their skills for emergency situations and evaluating life and non-life.
These things are exceedingly rare, but when they happen, they get our attention. One 78-year-old man in Mississippi in hospice care was pronounced dead after no signs of life and no pulse. He was placed into a body bag and transported to the coroner's office.
When he was taken to the embalming room, his legs began kicking. He also began to breath a little. The coroner's office called the paramedics. Yes, coroner's don't necessarily need medical degrees (scary though, eh?).
The explanation? Possibly the defibrillator implanted under his skin had jumpstarted his heart again.
Any way you look at it, I would say my directive would be to have someone present with me for a full hour after my passing and have medical staff re-review my actual demise, thank you, please.