Ultraweak Photon Emission is the energy released as light through the changes in energy metabolism. It is a spontaneous very low intensity photon emission in the visible and ultraviolet spectrum emitted by all living organisms, including humans. The human body literally glimmers. The intensity of the light emitted by the body is 1000 times lower than the sensitivity of our naked eyes.
This low intensity glow cannot be seen by the naked eye, but can be measured by sensitive photomultiplier tubes (PMTs) and CCD cameras that are designed to amplify these weak signals. (Kobayashi, et. al., 2009) successfully imaged the diurnal change of this ultraweak photon emission with an improved highly sensitive imaging system using cryogenic CCD camera. They found that the human body directly and rhythmically emits light and that the diurnal changes in photon emission might be linked to changes in energy.
(Source: https://www.hamamatsu.com/us/en/R1527.html and http://www.andor.com/scientific-cameras/ixon-emccd-camera-series/ixon-ultra-897)
Systematic studies on human emission have presented information on: (a) procedures for reliable measurements, and spectral analysis, (b) anatomic intensity of emission and left-right symmetries, (c) biological rhythms in emission, (d) physical and psychological influences on emission, (e) novel physical characteristics of emission, and (f) the identification of ultraweak photon emission with the staging of Reactive Oxygen Species (ROS)-related damage and disease (Van Wijk R, et. al., 2008). This study also concluded that both patterns and physical properties of ultraweak photon emission hold considerable promise as measure for the oxidative status.