A man from Victoria who came back from the dead has opened up about what he saw. Photo / 123RF
What happens when we die is one of life's biggest mysteries.
One man who knows more about the topic than most is Alistair Blake, who went to the other side and back again.
Three years ago, Alistair fell into cardiac arrest during his sleep.
"Technically, I was dead for 90 minutes," he told news.com.au's I've Got News For You podcast.
It had been a fairly normal day for Alistair, who has a history of heart disease in his family. He rode 45 kilometres on his bike and spent time with Melinda – his wife of 35 years – before he headed off to bed.
But at 3.10am, Melinda woke to find Alistair having a medical episode.
"She's a light sleeper and woke to me gurgling," Alistair said. "She grabbed her mobile phone and dialled triple-0 to get a hold of the ambulance and they instructed her to take me off the bed to be able to do CPR.
"She did CPR for 20 minutes … then the paramedics turned up. They did CPR and hit me with the defib. Apparently, it was something in excess of 10 to 12 times."
It didn't look good for Alistair, and the police took Melinda into another room and told her that her husband was unlikely to survive.
For 90 minutes, paramedics fought to restart Alistair's heart, and just when they were about to stop, they miraculously found a pulse.
Almost a week later, Alistair woke up at Frankston Hospital and remarkably there were no signs of a brain injury.
As a result, his medical team nicknamed his 'Lazarus' – the man who was raised from the dead.
Alistair told I've Got News For You that he doesn't remember too much from the medical episode and his time in hospital.
"I remember going to bed on the Saturday night – and the next thing I remember was waking up Thursday morning on a trolley going from ICU to coronary care," he said. "The human brain has totally blocked out what happened in between.
"A lot of people ask me if I saw anything, and no, I did not see anything," he said. "No bright lights, nothing like that whatsoever."
Alistair is one of the many people who have opened up about their near-death experiences.
And even though he didn't see something on the other side, plenty of other people have.
Jessie Sawyer from the US told Inside Edition that she saw her late best friend when she had a near-death experience.
"In the distance I saw someone waiting … Anthony had died two years before, and then I realised this was about me, this wasn't some joyous reunion but something serious was happening," she said.
"Behind Anthony, to my right, the light started to appear – and that's when I realised this was death. This was my death and Anthony was there to take me home."
Another woman, Cynthia Busch, told Oprah that she saw her late grandmother when she had a near-death experience.
"I saw this long hall and this bright white light and lots of clouds, and then all of a sudden I saw my grandmother and I freaked (out)," Cynthia recalled. "I thought, I must be dead! How else would I see her … she kept telling me to go back."
One man who had a similar experience to Alistair was the late Kerry Packer.
The former Channel 9 owner was dead for eight minutes after suffering a heart attack in 1990.
"I've been on the other side son, and let me tell you, there's nothing f***ing there," Packer famously said.
Experts believe the reason people who have been through near-death experiences see different things is simply because of the way the brain reacts when the oxygen supply is cut off.
Patrick Steele, a Palliative Care Consultant from Palliative Care South East, explained to I've Got News For You the scientific and spiritual reasons behind the mysterious white light.
"From a spiritual perspective, some people believe that the bright light is a glimpse into the afterlife or a sign that consciousness is leaving the brain," he said.
"From a psychologist's perspective, some say it's more of a defensive mechanism or some say it's a flashback to earlier memories.
"From a medical perspective – and the one that I adhere to most – is that it's more of a change in how our body is functioning, particularly the brain.
"The brain, as you know, needs a lot of oxygen and blood supply to do its job effectively. Whenever that oxygenation is cut off, the brain doesn't act normally," he said.
Steele compared the bright light to an experience that many people have when they faint.
"The change of blood supply that occurs in the brain due to low blood pressure results in a sort of tunnelled vision, so the darkness comes in from the outside before you pass out," he said. "For me, this (white light) is a more exaggerated version of fainting."