For centuries, people have spoken about a mysterious “spark of life” a vital energy that separates the living from the dead. Now, scientists may have found a real, biological basis for that idea. A groundbreaking new study has revealed that all living organisms emit a faint, visible light while alive and that glow disappears the moment life ends.
Researchers from the University of Alberta and other institutions have used ultra-sensitive cameras to capture this soft glow, known as ultraweak photon emission (UPE), in living mice. Their findings, published in The Journal of Physical Chemistry Letters in 2025, offer one of the clearest pieces of evidence yet that life itself gives off light.
A Glow That Fades With Death
The experiment began with scientists using extremely sensitive imaging tools to monitor living mice in a dark environment. To their surprise, they observed a faint, visible light radiating from the animals’ bodies. This light was far too weak to be seen with the naked eye, but the cameras picked it up clearly.
The real breakthrough came when the mice were euthanized. The glow quickly faded away even though the bodies were carefully kept at the same temperature to ensure that heat wasn’t a factor.
This proved that the light wasn’t simply a byproduct of temperature or decay. Instead, it was closely tied to the animals’ living state. Once life ceased, the light vanished too.
Not Just Animals Plants Glow Too
The team also tested plants and found a similar effect. Leaves glowed more brightly in areas where they were damaged or exposed to chemical stress. This suggested that cells under stress produce more of this ultraweak light.
The discovery hints at a universal biological process shared across the tree of life from plants to mammals. All living cells seem to emit these tiny flashes of light while functioning, and this glow can change based on their health or stress levels.
What Causes the Glow?
The faint light comes from molecules known as reactive oxygen species (ROS). These molecules are created naturally inside cells, especially when the cells are stressed by toxins, heat, illness, or physical injury.
Reactive oxygen species can trigger chemical reactions inside cells, and some of those reactions release photons the basic units of light. Although scientists have known for decades that individual cells can emit these photons, the light was so weak that it could only be detected in small samples under laboratory conditions.
This new research is revolutionary because it shows the phenomenon occurring throughout entire living organisms, not just isolated cells. It’s the first time such a whole-body glow has been captured and studied in detail.
From Mystical “Auras” to Real Science
The discovery may sound like something out of science fiction or mystical belief systems that speak of “auras” or “life energy.” But scientists stress that this is not supernatural it’s a purely biological effect.
In fact, far from being just a curiosity, this light could have practical uses. Because UPE changes based on cellular stress, it might become a powerful new tool in medicine, agriculture, and biology.
Medical diagnostics: Doctors could use UPE imaging to monitor tissue health, detect illness earlier, or measure how patients respond to treatments all without invasive surgery or blood tests.
Animal research: Scientists could track stress and disease progression in lab animals without harming them.
Agriculture: Farmers could check the health of crops and detect problems long before visible symptoms appear.
A Window Into the “Light of Life”
While the idea that living things glow may sound poetic, this research shows it’s a scientific reality. Every living cell produces a tiny bit of visible light as part of its normal functions a glow that fades away when life itself ends.
It’s a powerful reminder that life leaves its mark not just in motion and breath, but also in light. And as scientists learn more about this hidden glow, it could open up new ways to see and understand the living world around us.
Source: V. Salari, V. Seshan, L. Frankle, D. England, C. Simon, and D. Oblak, “Ultraweak Photon Emission from Living Organisms,” The Journal of Physical Chemistry Letters (2025), 16 (17), 4354–4362.