A beckoning light; a feeling of transcendence: these are two characteristics of a near-death experience that new research suggests may relate to amounts of certain chemicals in the blood. "The phenomenon known as 'near-death experience' is the stuff of hospital dramas, a dramatic conceit for movies about do-overs and for a (I guess lucky) few of us, a mysterious peephole to 'the other side.' The phenomenon is very real: By various estimates, 11% to 23% of those who had experienced cardiac arrest and lived to tell about it report some unique cognitive experience -- an overwhelming feeling of transcendence, doors opening, beckoning light, a thumbnail life-review -- that broadly fits the description. (The Internet yields a bounty of personal accounts as well, so it must be real!) But their observations are not very well explained -- not, at least, by standard earthly measures."