Human biophoton emission and the physics hidden inside living cells. When people hear the phrase “humans glow,” most assume it is metaphorical. In reality, the human body does emit light, although not in a way visible to the naked eye. This phenomenon, known as ultraweak photon emission (UPE) or biophoton emission, refers to the release of extremely small amounts of visible light from living organisms. Unlike bioluminescence in fireflies or jellyfish, human light emission is