Tunnels, bright lights, visions of the deceased. Do near-death experiences really offer a glimpse of the afterlife—or is there a more rational explanation? New research shows that many critically ill kidney dialysis patients have similar near-death experiences, and that almost one in 10 heart-arrest survivors also report near-death experiences whose features include out of body sensations, bright lights, dark tunnels, and images of life events and spiritual entities. But there’s no consensus on what lies behind near-death experiences, even though they are being increasingly reported. Are they, as some people are convinced, signs of the soul leaving the body? Or are they, as others suggest, the last, dreamlike act put on by a dying brain?