Brain Energy, Blood Flow, and Near-Infrared Light

When we think about the brain, we often picture neurons sending signals. Those neurons work within a larger system that includes supporting cells and tiny blood vessels.

Mitochondria help cells produce usable energy. Blood vessels deliver oxygen and nutrients. The relationship between these processes is part of what makes brain energy an interesting subject for photobiomodulation research.

Meet the neurovascular unit

The neurovascular unit is a way of describing the close functional relationship between neurons, supporting cells such as astrocytes, and blood vessels. Studying these components together helps researchers ask how neural signaling and vascular responses interact.

This adds another layer to the familiar discussion of mitochondria and near-infrared light. A change in blood flow, an electrical signal, and a change in task performance each describe something different about the brain.

A 2025 bioRxiv preprint by Zhao and colleagues explored these relationships using transcranial light stimulation in healthy volunteers. The researchers combined photon-transport modeling with brain imaging and electrophysiological measurements. Read the research preprint.

Measuring more than one response

The study used 1064nm laser light and several methods for examining the brain’s response. Functional MRI and arterial spin labeling provided information about blood oxygenation signals and cerebral blood flow. EEG and measurements combining magnetic stimulation with EEG helped assess electrical activity and cortical excitability.

The researchers reported increased blood flow and BOLD signals in light-affected regions. Their electrophysiological findings also indicated reduced cortical excitability.

That combination is scientifically interesting: the vascular and electrical measurements did not simply move in the same direction. It shows why a rise in a blood-flow measurement should be interpreted alongside other evidence about neural activity. Research methods and findings.

From observation to explanation

To investigate how these responses might occur together, the team used a computational model incorporating inhibitory neural inputs. The model proposed a role for inhibitory activity and nitric oxide signaling in the vascular response.

This offers a possible explanation to test further. Nitric oxide release in the human brain was a model prediction in this work, rather than a directly measured result.

The distinction helps us see how science develops: researchers observe a pattern, build an explanation, and identify the next measurements needed to test it.

What this adds to the brain-energy conversation

For people interested in near-infrared light, this work broadens the discussion beyond a single cellular pathway. It points toward studying energy metabolism, blood supply, and neural activity as interacting parts of a system.

These physiological outcomes also need their own interpretation. Subjective calm, sleep quality, and everyday focus would require separate assessments; they cannot be inferred from these measurements alone.

Brainlume uses 810nm LEDs, so this 1064nm research contributes to the broader scientific background rather than establishing an effect of the wearable. Its value is in the question it brings into focus: how can we understand the brain’s response to light across several levels at once?

Continue exploring Brainlume’s science.

Reference

Zhao C, Li Z, Ding Z, et al. Effect of Transcranial Light Stimulation on the Neurovascular Unit in the Human Brain. bioRxiv. Version posted April 26, 2025.