Scientists Say: Biophoton

All life forms give off this extremely faint glow

a group of glowing people chat in a dimly lit room

Though too faint to be seen with our eyes, all living things emit faint light. The particles making up this light are called biophotons.

Cornelia Li

Biophoton (noun, “BY-oh-foh-tawn”)

Though it cannot be seen with the naked eye, all living things give off extremely dim light. The light particles, or photons, making up this glow are called biophotons.

Biophotons fall within the range of “visible light.” That is light with wavelengths our eyes can see. But the glow of biophotons is so faint that scientists need very sensitive instruments to detect it. Each square centimeter (0.15 square inch) of a person’s skin, for instance, gives off only around 1,000 photons per second. A firefly is about a million times as bright.   

Sometimes, a cell might emit biophotons in flashes. Other times, that cell might release this light as a steady stream. It’s not totally clear how biophotons form. But scientists believe they come from chemical reactions in cells. Oxygen-related chemistry seems to produce the most biophotons. And organs with more chemical reactions tend to produce more light.

The brain can appear quite bright by biophoton standards. Not only does the glow of active brain regions brighten. But the pattern of the light can change too. A person listening to music emits different light patterns than a person who’s just relaxing.

Certain cellular structures also give off more of this light than others. DNA can glow quite brightly. At times, it can even outshine fluorescent labels, which are chemical tags that help scientists light up molecules for imaging. Mitochondria are also biophoton-bright. These organelles carry out much of the oxygen-related chemistry within the cell.

Scientists hope to use their knowledge of biophotons to develop new technologies. For example, some want to use the brain’s biophoton glow to track brain activity. This may offer a less invasive alternative to current brain-imaging tech.

In a sentence

Biophotons are distinct from bioluminescence — a bright glow that only some species give off through well-studied chemical reactions.

Check out the full list of Scientists Say.

Katie Grace Carpenter is a science writer and curriculum developer, with degrees in biology and biogeochemistry. She also writes science fiction and creates science videos. Katie lives in the U.S. but also spends time in Sweden with her husband, who’s a chef.