Living beings emit a faint light that extinguishes upon death, study

Summary

Credit: The Journal of Physical Chemistry Letters (2025). DOI: 10.1021/acs.jpclett.4c03546 The light of someone's life might not be just another person, but light in the literal sense. According to a recent study by researchers from University of Calgary, every living system emits light without requiring external excitation due to a biological phenomenon known as ultraweak photon emission (UPE). In mice, UPE was linked to vitality as live mice emitted significantly higher UPE intensity compared to recently dead mice. In plants, however, UPE varied depending on exposure to stress factors like temperature changes, injury and chemical treatments, as reported in The Journal of Physical Chemistry Letters. Living organisms are compact biochemical labs where complex chemical reactions keep the system up and running. Cellular metabolism, a series of chemical reactions that fuel life-sustaining processes, produces a group of highly reactive oxygen-containing molecules produced as a natural byproduct called reactive oxygen species or ROS. Studies suggest that ROS plays a central role in UPE. When organisms encounter stress, they activate biochemical pathways that generate ROS, which act as signaling molecules in the cellular stress response. However, excessive ROS production can lead to oxidative stress, overwhelming the cell's antioxidant defenses. This oxidative stress can induce electron excitation and transfer processes, ultimately resulting in UPE. High-sensitivity EMCCD and CCD cameras for imaging UPE in dark, controlled environments. Credit: The Journal of Physical Chemistry Letters (2025). DOI: 10.1021/acs.jpclett.4c03546 Unlike bioluminescence, which produces high-intensity light visible to the naked eye, UPE, also known as biophoton emission, is a spontaneous release of extremely low-intensity light that is invisible to the human eye and falls within the spectral range of 200–1,000 nm. This faint light has been detected in a wide range of life forms—from single-cell...