A groundbreaking study published in iScience in March 2025 introduces “photoencephalography,” a novel technique that detects ultraweak photon emissions (UPEs) from the human brain. These UPEs are faint light signals produced during cellular metabolism, approximately a million times dimmer than visible light, and are emitted by all living tissues, including the brain. The research team, led by Hayley Casey, conducted experiments with 20 healthy adult participants in a dark environment, using photomultiplier tubes to capture these emissions from the occipital and temporal regions of the skull .

The study found that UPEs are not random but exhibit structured patterns that vary with cognitive states. For instance, emissions increased when participants closed their eyes and decreased during auditory stimulation, aligning with known changes in brain wave activity. These findings suggest that UPEs could serve as optical markers of brain activity, providing insights into mental states without the need for invasive procedures .

The underlying mechanism of UPEs involves oxidative metabolism, where reactive oxygen species (ROS) in cells return to a lower energy state, releasing photons in the ultraviolet-to-visible spectrum. In the brain, a highly metabolic organ, these emissions are thought to be linked to neuronal activity and oxidative processes. Unlike bioluminescence, which involves specific enzymatic reactions, UPEs are a byproduct of normal cellular metabolism and are extremely faint—about a million times weaker than visible light .

This research marks a significant advancement in non-invasive brain monitoring. By enabling the detection of UPEs through the skull, photoencephalography offers a new avenue for studying brain function and diagnosing neurological disorders. While still in its early stages, this technique holds promise for providing real-time insights into brain activity, potentially transforming our understanding of the brain and its complex processes.

1. PIIS2589004225002792.pdf