At University of Shanghai for Science and Technology, recent work by Professor Bo Song and colleagues suggests that light may play an unexpected role in the way our nerves use and transmit energy. Their research explores how mid-infrared photons, tiny packets of light released by chemical reactions inside nerve cells, might interact with the fatty myelin sheath tasked to insulate axons. Together, the studies propose a new view of biological communication —one that combines chemistry, physics, and quantum mechanics— to explain how the nervous system could use light to enhance energy efficiency and information transfer.

Light as a Biological Energy Carrier

For more than a century, nerve signals have been understood as electrical impulses moving from one nerve cell to the next, along their long tails called axons. Yet, biology often hides secondary layers of communication. Prof Song and colleagues suggest that beyond ions and electricity, nerves may also use light, specifically mid-infrared photons produced by chemical reactions.

A photon is the smallest unit of light energy. These photons may arise during metabolic reactions in mitochondria, the tiny powerhouses inside each nerve cell, or neuron. The group examined whether such photons could interact with the myelin sheath that surrounds the axons. This multilayered coating made of phospholipid molecules speeds up signal conduction between neurons.

Discovering the Cell Vibron Polariton

Prof Song and colleagues introduced the concept of a cell vibron polariton (cell-VP), a hybrid quantum state formed when light couples with molecular vibrations in a cell (eg, neuron). A vibron is the vibration of atoms within a molecule, and a polariton is a mixed state of light and matter that behaves as a single entity.

In physics, the word quantum refers to the smallest possible unit of energy, an amount so small that it follows the special rules of quantum mechanics. Thus, tiny particles like photons can also behave as waves and exist in overlapping states. These rules allow light and matter to become momentarily inseparable, sharing energy in perfectly synchronized motion. The researchers proposed that, within the myelin sheath of neurons, mid-infrared light emitted by mitochondria could become resonantly trapped. The sheath’s orderly lipid layers, each only a few millionths of a metre thick, create conditions similar to a microcavity that confines the light. When the frequency of the light matches the natural vibration of the lipid molecules, the two merge into a coherent superposition state of polariton. This cell-VP could exist stably at body temperature, enhancing the local electromagnetic field, and increasing the sheath’s ability to hold and guide light.

NAD-photons and the Tricarboxylic Acid Cycle

Building on this framework, the research team investigated where these mid-infrared photons might originate. Their 2023 work focused on the tricarboxylic acid (TCA) cycle, the sequence of reactions by which mitochondria extract energy from nutrients to produce adenosine triphosphate (ATP). During this process, a molecule called nicotinamide adenine dinucleotide (NAD⁺) binds hydrogen to become its reduced form, NADH.

The team calculated that this reduction releases photons with a frequency of approximately 87 terahertz, known as NAD-photons. Each photon carries an energy of about 35 kilojoules per mole, enough to influence nearby molecular bonds. Prof Song and colleagues propose these photons are not wasted but may be captured by the myelin sheath surrounding the neuron.

Resonant Capture Within the Myelin Sheath

The myelin sheath, rich in carbon–hydrogen (C–H) bonds, naturally vibrates at nearly the same 87 terahertz frequency as the NAD-photons. This coincidence allows resonant absorption, where light and molecular vibration share identical energies. The absorbed photons excite the lipid molecules, which then re-emit light that can be re-captured by neighbouring layers. Prof Song’s team modelled this as a cylindrical microcavity where standing light waves form between the inner and outer surfaces of the sheath. When these waves interact coherently with the lipid vibrations, a myelin polariton arises, a new hybrid state that links the energy of photons with the molecular structure of the sheath. The calculations showed that this state could exist stably under physiological conditions, resisting the random fluctuations of body heat.

How Quantum Coherence May Enhance Nerve Efficiency

The formation of a polariton changes the optical properties of myelin. By coupling light and vibration, the relative permittivity and refractive index of the sheath increase, allowing total internal reflection. This means that light can bounce within the sheath without escaping, effectively creating a natural waveguide. In this model, energy produced by metabolism is not lost as heat; it gets recycled as trapped light that may influence nerve conduction.

Theoretical analyses suggest that these hybrid light–matter states could transfer energy with minimal loss, a principle known from quantum physics as coherent energy transfer. In practice, this could help explain why biological systems operate with such extraordinary efficiency, converting chemical energy into function far more effectively than most artificial systems.

Implications for Neural Communication and Quantum Biology

The possibility that light and matter interact inside neurons invites a radical rethinking of brain function. If mid-infrared light can be generated and confined within myelinated axons, it may form part of a secondary communication network parallel to the well-known electrical system. The research team believe the polariton waves might tunnel across the tiny gaps between myelin segments, known as nodes of Ranvier, or even between neighbouring axons through glial connections. Such quantum tunnelling would allow energy or information to pass without conventional ion flow. While still theoretical, the model provides a basis for testing whether optical or quantum effects contribute to the brain’s exceptional speed and coherence.

Bridging Chemistry, Physics, and Life

These studies highlight how biological structures, evolved for one purpose, may serve several. The myelin sheath’s role as an electrical insulator could also make it an optical resonator, finely tuned by its dimensions and molecular composition. The same C–H bonds that build membranes also provide the vibrational frequencies needed to couple with light. By exploring these links, Prof Song and colleagues are developing a bridge between biochemistry and quantum optics, fields once thought unrelated. Their work invites experimental testing of whether mid-infrared light can influence neuronal activity, protein function, or even learning behaviour, as some preliminary findings in animal models already suggest.

Looking Ahead: From Quantum Nerves to Living Light

The concept that light generated within cells might guide or sustain biological processes represents a profound shift in perspective. If confirmed, it could change how we think about metabolism, neural efficiency, and consciousness itself.

Future research may explore how external mid-infrared light interacts with these internal processes, whether it can enhance recovery from injury, or be used to modulate brain activity non-invasively. For now, Prof Song and her team demonstrated that even within the familiar architecture of the nervous system, new physical principles may be waiting to be uncovered, where the boundary between energy, light, and life becomes beautifully blurred.