You glow in the dark! Too weak to see, human bioluminescent emissions vary by time of day. Faces are brightest.
The intensity of the light emitted by the body is 1000 times lower than the sensitivity of our eyes.
The daily variation of photon emission was measured with a sensitive CCD camera. In all images, photon emission intensity from the face was higher than from the body.
Photon emission formed a peak at late afternoon, then gradually decreased and stayed low until 7:00 AM.
The photon emission mechanism is thought to originate from the generation of free radicals in energy metabolic processes.