Researchers in Japan have discovered that the human body does indeed give off light within the visible spectrum. The downside is that it is of such a low intensity, as to be invisible to the naked eye. Using extremely sensitive cameras, the scientists noted that the light seems to be related to the daily sleep cycles we all experience.
While not really giving any proof that the auras some people claim to see are such light, it does show some interesting pieces of the puzzle. Note that the intensity of the light is over a thousand times below the normal human threshold of vision.
I’d still like to see how this light fades at death if at all, as well as the effects of various meditations and other mental states.