Human hands glow but fingernails release the most light, according to a recent study that found that all parts of the hand emit detectable levels of light.

The findings support prior research which suggested that most living things, including plants, release light. Since disease and illness appear to affect the strength and pattern of the glow, the discovery might lead to less invasive ways of diagnosing patients.

Mitsuo Hiramatsu, a scientist at the Central Research Laboratory at Hamamatsu Photonics in Japan, who led the research, told Discovery News that the hands are not the only parts of the body that shine light  by releasing photons, or tiny, energised increments of light.

"Not only the hands, but also the forehead and bottoms of our feet emit photons," Hiramatsu said, adding that, in terms of hands, "the presence of photons means that our hands are producing light all of the time."

The light is invisible to the naked eye, so Hiramatsu and his team used a powerful photon counter to "see" it. The detector found that fingernails release 60 photons, fingers release 40 and the palms are the dimmest of all, with 20 photons measured.

Fritz-Albert Popp, a leading world expert on biologically related photons at the International Institute of Biophysics in Germany, was not surprised by the findings. Popp and his team believe that the light from the forehead and the hands pulses out with the same basic rhythms, but that these pulses become irregular in unhealthy people. A study he conducted on a muscular sclerosis patient seemed to validate the theory.

Source:  Discovery News, September 6, 2005 (from Nexus Magazine, Dec."05 - Jan.'06)