This book reports the results of the first long-term prospective study of near-death experiences (NDEs) to be undertaken in the United Kingdom. The project studied the NDEs of patients in an intensive therapy unit in a Welsh hospital over a five-year period. The author worked as a Staff Nurse on the ITU ward during the study period, allowing her to closely correlate the medical conditions of her patients with their near-death experiences. The research produced several important findings, and the author was awarded a PhD degree by the University of Wales, Lampeter for this work. Only 2 of her patients initiated the report of their NDE, suggesting that such experiences may be under-reported. In several cases she was able to sample the blood gases of patients during the time of their NDE, and these results contradict the theories that NDEs are caused by either low oxygen levels or high carbon-dioxide levels. She also found that patients who did not report NDEs gave broadly inaccurate accounts when asked to guess how their resuscitation proceeded, while those who did report an NDE with an OBE component gave broadly accurate reports of the resuscitation procedure. This undermines the suggestion that NDE OBE reports are a mixture of prior knowledge, fantasy and guesswork, as some have hypothesized. Overall, the study underscores the challenge that NDEs present to explanation in orthodox medical terms.