Studying near death experiences

Scientists plan study of near death experiences. The article doesn't explain how they control the conditions of this study. How do you get people who are about to die, temporarily? The article goes over interesting ideas on near death experiences:

But Blackmore has examined all the arguments and believes she knows what causes these NDE visions. Firstly, the light at the end of the tunnel is simply "noise" in the visual cortex. It is often experienced by epileptics, migraine sufferers and those who meditate. It is not unique to NDE.
The out-of-body experience? Well, if you think about the last time you walked along a beach, for example, where do you see yourself? Probably not through your eyes, but from a vantage point above or to the side of you. Most people have a bird's-eye view of themselves when remembering past events. What Blackmore found in her own studies is that people who dream from a bird's-eye perspective are more likely to have out-of-body experiences.