The biggest ever scientific study of near-death experiences shows that awareness can continue for a surprisingly long duration after the brain has shut down completely. The finding suggests that these experiences are more than just hallucinations — and that our definition of clinical death should probably be revised.
Near-death experiences (NDEs) and out-of-body experiences (OBEs) have long been documented. They're particularly common among people who have suffered a cardiac arrest (CA). First responders or physicians are told to make a declaration of death when, after a variable length of time, there's no cardiac output, no respirations, and the pupils have become fixed and dilated. But in those very early stages after a CA, when cerebral blood flow and electrical brain activity are impaired or null, some people experience a wide range of subjective phenomenon. Survivors talk about "seeing a tunnel," a "mystical being," "feelings of peace," a feeling of separation from their bodies, and awareness of things during the episode or event.