Near death experiences (NDE) could be caused by something as ordinary as high levels of carbon dioxide, scientists suggest.
People who claim to have felt such experiences describe them as life flashing before their eyes, feelings of peace and joy and paranormal encounters.
It is described by someone who has been stated clinically dead or appears to have been very close to death.
Many scientists put them down to hallucinations while psychics or religious groups are more likely to consider them as evidence of an afterlife.
A number of studies have been undertaken over the years but this is the first one that has taken carbon dioxide levels into consideration.
Slovenia-based scientists studied 52 patients, whose hearts had stopped, using questionnaires to determine whether or not they had had an NDE. Eleven patients reported NDEs, with more incidences among those with a higher absorption of carbon dioxide in the breath and arteries.