Ultraweak Photon Emission in Biological Systems

Ultraweak photon emission (UPE), often termed biophoton emission, refers to the spontaneous release of light in the visible to near-infrared spectrum by living organisms. Originating primarily from electronically excited species generated during oxidative metabolic processes, UPE arises through the formation and decay of reactive intermediates such as triplet carbonyls and singlet oxygen. Initially observed as diurnal rhythm of human body glow, biophoton emission has since been detected across microorganisms, plants and animal tissues. Advances in highly sensitive imaging and photon-counting detectors have revealed that these emissions reflect physiological states, oxidative stress levels and even neural activity. Although the absolute intensity is many orders of magnitude below visual threshold, the spectral and temporal patterns carry information about underlying biochemical pathways. Research has explored potential roles of UPE in intercellular communication, neural signal transmission and as a non-invasive biomarker for disease and food quality. The field interconnects photobiology, oxidative biochemistry and neuroscience and continues to uncover global applications ranging from diagnostics to forensic analysis.

Research from Nature Portfolio

Recent theoretical modelling has proposed that myelinated axons may function as intrinsic photonic waveguides, guiding biophotons generated by neuronal processes over biologically relevant distances. This work demonstrates that axonal geometry and refractive-index contrasts can support light propagation with tolerable losses, offering a plausible mechanism for targeted optical signalling alongside electrochemical synaptic transmission. In parallel, studies have established ultraweak photon emission as a dynamic tool for monitoring oxidative stress in real time. By inducing respiratory bursts in cultured immune cells, researchers recorded synchronous increases in biophoton flux that correlated with metabolic and redox changes. This approach enables continuous, label-free assessment of reactive oxygen species generation and offers a versatile readout for evaluating pharmacological inhibition of NADPH oxidase and other oxidoreductases.

Ultraweak Photon Emission in Biological Systems publication trend

The graph below shows the total number of articles in ultraweak photon emission in biological systems across all publications each year (not limited to Nature Index journals).

Technical terms

Ultraweak photon emission (UPE): Spontaneous release of low-intensity photons from biological systems during oxidative metabolic reactions.

Reactive oxygen species (ROS): Highly reactive molecules derived from oxygen metabolism that can generate electronically excited intermediates.

Photonic waveguide: A structure that confines and directs light, proposed here as myelinated axons guiding biophotons.

Bio-nanoantenna: Array of nanometre-scale structures, such as ion channels, that can emit or receive electromagnetic radiation.

Oxidative stress: Imbalance between production of ROS and antioxidant defences, often assessed via changes in UPE intensity.

References

1. Unveiling long-range forces in light-harvesting proteins: Pivotal roles of temperature and light. Science Advances (2025).
2. Reduced biophotonic activities and spectral blueshift in Alzheimer’s disease and vascular dementia models with cognitive impairment. Frontiers in Aging Neuroscience (2023).
3. Influence of External Light on Ultra-Weak Photon Emission of Fruits: Forensic Differentiation of Organic and Conventional Fruits. Sensors (2025).
4. Mechanism of the Formation of Electronically Excited Species by Oxidative Metabolic Processes: Role of Reactive Oxygen Species. Biomolecules (2019).
5. Possible existence of optical communication channels in the brain. Scientific Reports (2016).
6. Ultra-weak photon emission as a dynamic tool for monitoring oxidative stress metabolism. Scientific Reports (2017).
7. Node of Ranvier as an Array of Bio-Nanoantennas for Infrared Communication in Nerve Tissue. Scientific Reports (2018).
8. Spatiotemporal Imaging of Glutamate-Induced Biophotonic Activities and Transmission in Neural Circuits. PLOS ONE (2014).
9. Imaging of Ultraweak Spontaneous Photon Emission from Human Body Displaying Diurnal Rhythm. PLOS ONE (2009).
10. Triplet Excited Carbonyls and Singlet Oxygen Formation During Oxidative Radical Reaction in Skin. Frontiers in Physiology (2018).