Human Brain Literally Emits Light Through Your Skull, Study Finds

In a groundbreaking discovery, researchers have found that the human brain emits faint light signals that can pass through the skull and may change in response to mental activity. The study, published in the journal iScience, offers the first evidence that these ultraweak photon emissions (UPEs) might serve as a non-invasive way to monitor brain function, a technique the researchers are calling "photoencephalography."

UPEs are natural light emissions that occur during normal cellular metabolism. Unlike bioluminescence seen in organisms like fireflies, UPEs do not rely on specialised glowing chemicals and are a million times fainter than visible light.

According to the study published with the title "Exploring ultraweak photon emissions as optical markers of brain activity," these light signals are constantly produced by living tissue and may offer insight into brain health and activity.

The research team, led by scientists from Algoma University, Tufts University, and Wilfrid Laurier University, studied 20 healthy adults in total darkness. Using light-sensitive sensors placed on the skull and EEG caps to track brain waves, they recorded the brain's light emissions while participants completed simple tasks like closing their eyes or listening to sounds.

They discovered that the brain's photon emissions were distinguishable from background light and fluctuated in rhythmic patterns, especially in regions associated with visual and auditory processing. These light signals also showed changes based on mental state, such as eyes open vs. eyes closed, suggesting a link to brain activity.

Though still in early stages, the research paves the way for future technologies that could use these emissions to passively study the brain, potentially aiding in the diagnosis or tracking of neurological disorders.

"We view this as a proof-of-concept," the authors said, calling for further studies with better equipment and larger samples to unlock the full potential of this optical brain monitoring method.