You're Glowing

image by Kobayashi et al.

A recent observation by Japanese scientists gives new meaning to the words "you're glowing". Along with fireflies and jellyfish, humans emit small quantities of light, about 1000 times lower than what our eyes can detect. Place a human in front of a super-sensitive photon-detecting camera in the dark, however, and watch him glow! When imaging five healthy males for 20 minute intervals every 3 hours, researchers determined that the levels of "glowing" fluctuated throughout the day, peaking by 4 PM. The face exhibited the most amount of glow. The cause of glowing is likely due to the byproduct of chemical reactions taking place in our bodies involving free radicals, with glow fluctuations reflecting changes in our metabolism during the day.

Reference: Kobayashi M, Kikuchi D, Okamura H. (2009) Imaging of ultraweak spontaneous photon emission from human body displaying diurnal rhythm. PLoS ONE 4(7): e6256.doi:10.1371/journal.pone.0006256