The human body “literally shines”. We just don’t notice it because our naked eye can’t detect the phenomenon.
It’s no longer news that some members of the animal kingdom glow. Suddenly, fireflies or jellyfish come to mind. Although it is too faint to be detected, the bioluminescent glow is also pronounced in humans. It is linked to metabolic processes regulated by our circadian rhythms.
In a 2009 study, researchers observed five male participants in their 20s under controlled light and dark conditions using highly sensitive cryogenic CCD (charge-coupled device) cameras.
These cameras, capable of detecting light at the photon level, captured the participants’ faint biophotonic emissions. Interestingly, the intensity of the glow varied throughout the day, with the face being the brightest area.
The study in PLOS related these variations to the circadian rhythmsthe internal biological clock that regulates physiological processes. Cortisol, the hormone associated with these rhythms, was measured using saliva samples and the data correlated with changes in biophotonic emissions.
“The human body literally glows”write the authors of the study, cited by , but “the intensity of the light emitted by the body is 1000 times lower than the sensitivity of our naked eyes”.
According to the authors, the glow originates from reactive oxygen species produced by cellular mitochondria as a byproduct of energy production. The species interact with proteins, lipids and fluorophores, creating biophotons that cause the body to emit light.
This metabolic byproduct is a reflection of the internal workings of our body. Unlike the enzymatic reactions that cause bioluminescence in certain species, human glow is a non-enzymatic process linked to oxidative metabolism.
The researchers also suggest that this phenomenon, although tenuous, is more widespread in the animal kingdom than previously thought.
