Recalling the moment after your heart attack, you remember floating above yourself, watching your own operation with vivid detail. You shout at the doctors that you’re awake, and suddenly you’re heading into a bright white light, the whitest white you’ve ever seen. There’s people; your dead mom, your deceased cousin, your grandpa that passed away five years ago, and suddenly there’s a flash, and after that, nothing. Just oblivion.

You’ve just had an NDE, or near-death experience. They are not necessarily after a heart attack, but can also be experienced in skating-on-death situations, such as falling of a cliff, continuous fainting, serious diseases, and seconds before a catastrophic accident. Believe it or not, around 4 to 18% of people that clinically died and were successfully resuscitated report experiencing NDEs. Classic NDE symptoms include out-of-body-experiences, bright lights, dead relatives, beautiful figures, and tunnels. Some people say they were lead by a relative or figure through past events in their lives, memories recalled with perfect vivid detail, every emotion re-experienced. They feel they are dead, but eventually are told that it is not their time and return into their bodies, usually through their head. After waking up, NDErs usually have almost no remaining fear of death, and say the NDE helped them. NDEs are thought to occur during the time between dying and resuscitating.

So what is the cause of these NDEs? There are many different theories as to the cause of these mysterious occurrences. Maybe the brain is just starved for oxygen, and simply hallucinating. But many NDErs report it was ‘real, realer than real life.’ Maybe the experience is showing we have consciousness outside our own brain. Maybe it proves our instinct of survival. Maybe it’s just a sleep disorder. Maybe it even lies outside of the world of science, and is simply the doings of an unexplainable force, greater than our own.

One theory believed to explain NDE experiences is that consciousness exists outside our brain, and we no not need a fully working brain to be conscious. That would explain why NDEs are thought to occur after the EEG (electroencephalogram) line goes completely flat. A flat line occurs between 11 to20 seconds after the heart fails, and means that all brain waves shut down. Doctor Pim Van Lommel believes that the brain is only a messenger for consciousness, and is there to give us consciousness, not create it. After all, “Nobody sees the world in quite the same way as any other person.” Van Lommel believes that consciousness can also be perceived in some other dimension, and does not need our ways of time and space to function. He thinks that the brain is like a TV, decoding information from electromagnetic waves. It’s a wide-blown, but possible idea.

Another theory thought to clarify the reason for these amazing occurrences is our instinct of survival. It is thought to be our most powerful, as humans are animals. The theory is, that when the heart stops and cuts off all oxygen from the brain, it goes into an all-out defense, as if it is its last hope. Waves of neurotransmitters are created and release billions of tiny pictures and feelings from past memories. Maybe the life memories are really the brain searching its memories for a survival technique. The light and tunnel could even be explained away by damage to the back and sides of the brain. This theory also covers most of the symptoms.

A third theory supposed to simplify the cause of NDE experiences is REM, a sleep disorder called rapid eye movement. REM is when you mind awakens from sleep before your body, so you can’t move your muscles but your brain is awake. This results in mixed-up images, hallucinations, and intermingled states of consciousness. IN fact, in a recent study, 60% of tested NDErs report having experienced at least one episode of REM. Of course, that still leaves room for the other 40%.

The last big theory everyone knows is God, or simply a greater power above us. Maybe the NDE was the road to heaven, Al Yanna, or whatever your religion has. Maybe those special people were chosen to remain on earth and were given back precious time for life. This always remains a possibility.

Whether you choose science or faith, NDEs are still breath-taking experiences that are truly once-in-a-lifetime.