The human body emits a constant, though extremely weak, stream of light known as ultra-weak photon emission (UPE) or biophotons. This light is produced by cellular and metabolic processes but is far too faint for the naked eye to perceive.
UPE refers to the very low levels of visible light emitted by living organisms, including humans, as a byproduct of their metabolic and cellular activity. The intensity of this light is incredibly low, about 1000 times lower than what the human eye can detect. Scientists use specialized equipment to image and study these faint light emissions.
UPE is believed to be related to cellular and metabolic processes and may offer insights into health and disease. Some studies suggest it could potentially be used as a non-invasive tool for health diagnostics. The intensity of UPE can vary based on factors like stress, health status, and even the time of day. Research indicates that UPE ceases when an organism dies, as the biochemical processes that produce it stop.
Research
Calcerrada, M., & Garcia-Ruiz, C. (2018). Human Ultraweak Photon Emission: Key Analytical Aspects, Results and Future Trends – A Review. Critical Reviews in Analytical Chemistry.
Casey, H., DiBerardino, I., Bonzanni, M., Rouleau, N., et al. (2025). Exploring ultraweak photon emissions as optical markers of brain activity. iScience.
Du, J., Deng, T., Cao, B., Wang, Z., et al. (2023). The application and trend of ultra-weak photon emission in biology and medicine. Frontiers in Chemistry.
Ives, J., Van Wijk, E., Bat, N., Crawford, C., et al. (2014). Ultraweak photon emission as a non-invasive health assessment: A systematic review. PLOS One.
Kobayashi, M., Kikuchi, D., & Okamura, H. (2009). Imaging of ultraweak spontaneous photon emission from human body displaying diurnal rhythm. PLOS One.
Mould, R., Mackenzie, A., Kalampouka, I., Nunn, A., et al. (2024). Ultra weak photon emission — A brief review. Frontiers in Physiology.
Pietruszka, M., Marzec, M. (2024). Ultra-weak photon emission from DNA. Scientific Reports.
Salari, V. Seshan, V., Frankle, L., England, D., et al. (2025). Imaging ultraweak photon emission from living and dead mice and from plants under stress. The Journal of Physical Chemistry Letters.
Van Wijk, R., & Van Wijk, E. (2005). An introduction to human biophoton emission. Research in Complementary Medicine.
Additional Information
All humans emit subtle light until they die, study suggests | Science Focus
All living things emit an eerie glow that is snuffed out upon death | New Scientist
Every human body gives off an invisible glow — Here’s what it means | Popular Mechanics
Humans glow in a visible light that disappears in death, study finds | Brighter Side of News
We emit a visible light that vanishes when we die, says surprising new study | Science Alert
