What is brain photobiomodulation?
The brain is the most important and complex human organ. Within every brain cell are mitochondria, which are best understood as energy-producing “powerhouses” or “batteries”. Through biochemical reactions, the mitochondria create fuel for brain cells.
Your brain’s mitochondrial performance can be improved by absorbing light energy (photons) of specific wavelengths. This process is called photobiomodulation (PBM). Scientific research shows our brain’s mitochondria respond positively to light energy within the NIR wavelength range.
When NIR energy from, for example, a Vielight Neuro, is delivered to neuronal mitochondria, it is absorbed by a light-sensitive enzyme called cytochrome c oxidase. This enzyme uses NIR energy to start a series of biochemical reactions that are both beneficial and energizing to the neurons and other brain cells.
Collectively, brain photobiomodulation heals damaged brain cells, improves cerebral blood circulation, reduces inflammation and toxicity, and regenerates damaged brain cells. In a nutshell, NIR light energy to the brain improves efficiency and performance due to better signaling and repaired connectivity between the neurons.
The NIR spectrum of light energy provides the deepest penetration into brain tissues that also result in benefits. We have chosen the NIR wavelength of 810 nm based on the NIR window. To determine the optimal parameters for PBM, research that uses Vielight technology often employ brain imaging and brain signaling techniques.
Penetration of Light Energy
Research and clinical studies indicate that when NIR light energy has sufficient power density, it is capable of penetrating biological tissue and bone to produce therapeutic outcomes without negative side effects.
What is NIR light energy?
Near infrared light (NIR) energy is part of the electromagnetic spectrum – which are waves (or photons) of the electromagnetic field.It radiates through space and carries electromagnetic radiant energy. Several existing technologies depend on the ability of electromagnetic energy to penetrate solid objects, such as WiFi, mobile data, radar and navigation satellites.
Figure 1 The electromagnetic spectrum
The depth or the power of penetration by light energy depends on the wavelength in the electromagnetic spectrum. Thus, the longer the wavelength, the greater the ability for photons to penetrate an object. NIR light energy is found around the center of the electromagnetic spectrum.
Why near infrared light energy for brain photobiomodulation?
The optical window is the range in the electromagnetic spectrum where light has a maximum depth of penetration in tissue. This is because the optical window is defined by the absorption of photons by blood at the shorter wavelengths and by water at the longer wavelengths. NIR light energy, within the optical window, also derives the greatest mitochondrial response out of the entire electromagnetic spectrum.
Figure 2 The optical window
Image source: Wang, Erica & Kaur, Ramanjot & Fierro, Manuel & Austin, Evan & Jones, Linda & Jagdeo, Jared. (2019).
Safety and penetration of light into the brain. 10.1016/B978-0-12-815305-5.00005-1.
In particular, visible light (wavelength 400 to 700 nm) is substantially absorbed by hemoglobin and other organic matter. On the other hand, absorption by water increases at wavelengths longer than near infrared light (1000+nm). This implies that wavelengths outside of the near-infrared window cannot penetrate deeply through tissue.
Penetration through the skull using NIR LED technology
Several independent published studies support the ability of NIR LED technology to penetrate the skull and irradiate the brain., ,  Lasers are not necessary and harbor inherent unnecessary dangers, due to the nature of coherent light energy – power throttling and overheating tend to occur. The common factor is the wavelength range of 800-830nm, which falls within the body’s optical window.
Mechanisms of Brain Photobiomodulation
Figure 3 Photobiomodulation of cytochrome c oxidase
Brain photobiomodulation (PBM) utilizes red to near-infrared (NIR) photons to stimulate the cytochrome c oxidase enzyme (chromophore/complex IV) of the mitochondrial respiratory chain. Cytochrome c oxidase is receptive to light energy. This results in an increase in ATP synthesis, leading to the generation of more cellular energy. Additionally, photon absorption by ion channels results in release of Ca2+ which leads to the activation of transcription factors and gene expression.
- Published study (May 2022) using the Vielight Neuro Alpha on how neurons and cellular components such as microtubules and tubulin respond to near-infrared PBM.
- Published study (April 2019) using the Vielight Neuro Gamma on how near-infrared PBM could positively cognition, memory consolidation and mental energy.
There are several mechanisms associated with promoting physiological change through photobiomodulation therapy (PBMT). The wavelengths primarily used with PBM is within the near-infrared range of the electromagnetic spectrum with a sufficient power density. When hypoxic/impaired neurons are irradiated with low level NIR photons, this triggers an increase in mitochondrial adenosine tri-phosphate (ATP) production within their mitochondria.,  Another change is the release of nitric oxide from impaired/hypoxic neurons.
In hypoxic neurons: cytochrome-C oxidase (CCO), a membrane-bound protein that serves as the end-point electron acceptor in the cell respiration electron transport chain, becomes inhibited by non-covalent binding of nitric oxide. When exposed to NIR photons, the CCO releases nitric oxide, which then diffuses outs of the cell – increasing local blood flow and vasodilation., 
Following initial exposure to the NIR photons, there is a brief burst of reactive oxygen species (ROS) in the neuron cell, and this activates a number of signaling pathways. The ROS leads to activation of redox-sensitive genes, and related transcription factors including NF-κβ.,  The PBMT stimulates gene expression for cellular proliferation, migration, and the production of anti-inflammatory cytokines and growth factors.
Therapeutic Outcomes of Brain Photobiomodulation
Figure 4 Cascading cellular effects of photobiomodulation
Figure 5 The therapeutic outcomes of brain photobiomodulation
The absorption of red to NIR photons by mitochondria CCO triggers a series of cellular and physiological effects occur in the brain, also known as CCO upregulation.
CCO upregulation leads to:
- A small increase in reactive oxygen species (ROS), which activate mitochondrial signaling pathways linked to neuroprotection. 
- An increase in nitric oxide (NO) which stimulate vasodilation and cerebral blood flow.
- An increase in ATP production 
Combined, these effects trigger and improve the activation of signaling pathways and transcription factors that modulate the long-term expression of various proteins and metabolic pathways in the brain. Additionally, electrophysiological effects on the human brain have also been demonstrated by PBM in older people.[7, 8]
Metabolic effects and brain oxygenation
The metabolic effects of PBM in the elderly have been shown to increase cerebral blood flow (CBF) due to the increase in CCO activity, leading to an increase in brain oxygenation. Photobiomodulation of the prefrontal cortex was able to increase the resting-state EEG alpha, beta and gamma power, and more efficient prefrontal fMRI response, facilitating cognitive processing in the elderly.  Additionally, photobiomodulation of the Default Mode Network (DMN) has also been shown to increase cerebral perfusion due to an increase in mitochondrial activity. 
Brain PBM and anti-inflammatory effects
In addition to the above findings, PBM may be a promising strategy for improving aging brains because of its anti-inflammatory effects. [10, 11]
Brain PBM leads to a reduction in neuronal excitotoxicity
In 2022, researchers from the University of Alberta published a multi-layered study investigating the way that living cells, cellular structures, and components such as microtubules and tubulin respond to near-infrared photobiomodulation (NIR PBM) using the Vielight Neuro Alpha.
Their study showed that PBM balances excitatory stimulation with inhibition, indicating that PBM may reduce excitotoxicity which is relevant to the maintenance of a healthy brain. This study also showed that low-intensity PBM upregulates mitochondrial potential and improves physiological brain functions impaired due to trauma or neurodegeneration. 
Brain PBM increases cerebral vascularity and oxygenation
Aging is accompanied by changes in tissue structure, often resulting in functional decline. The blood vessels within the brain are no exception. As one ages, a decrease in blood flow to the brain is caused by a loss of cerebral vascularity, leading to cognitive decline when neurons cannot obtain sufficient oxygen. Brain photobiomodulation has also been shown to increase cerebral blood flow due to the vasodilation that occurs after the release of nitric oxide.
Brain Photobiomodulation Applications
The literature on brain photobiomodulation is growing rapidly. Currently, there are over 220 published studies on brain photobiomodulation.
Brain photobiomodulation has been shown to increase cerebral perfusion and increase connectivity within the Default Mode Network of patients with Alzheimer’s disease and dementia.,
In patients with Parkinson’s disease, measures of mobility, cognition, dynamic balance and fine motor skill y improved (p < 0.05) with PBM treatment for 12 weeks and up to one year.
There is scientific literature that suggests photobiomodulation might be useful for depression/anxiety.
Photobiomodulation has also been shown to induce positive physiological changes for traumatic brain injury.
EEG neural activity can also be influenced by pulsed NIR energy.,
We can expect many more research outcomes of PBM featuring the use of Vielight technology in the near future.
Published Brain Photobiomodulation research
Effects of Home Photobiomodulation Treatments on Cognitive and Behavioral Function and Resting-State Functional Connectivity in Patients with Dementia: A Pilot Trial
Institutes – University of California San Francisco & the Veterans Affairs USA
[ Published Study Link (Photomedicine and Laser Surgery, 2018) ]
Significant Improvement in Cognition in Mild to Moderately Severe Dementia Cases Treated with Transcranial Plus Intranasal Photobiomodulation: Case Series Report
Co-authoring institutes – Harvard Medical School, Boston University School of Medicine
[ Published Study (Photomedicine and Laser Surgery, 2015) ]
Improvements in clinical signs of Parkinson’s disease using photobiomodulation: A prospective proof-of-concept study
Institutes – University of Sydney, University of New South Wales, Griffith University
[ Published Study Link (Liebert, 2021) ]
Traumatic Brain Injury / Concussion
Changes in Brain Function and Structure After Self-Administered Home Photobiomodulation Treatment in a Concussion Case
Institutes – VA Advanced Imaging Research Center, San Francisco VA Health Care System, Departments of Radiology & Biomedical Imaging and Psychiatry & Behavioral Sciences, University of California, San Francisco
[ Published Study Link (Frontiers, Neurology, 2020) | National Center for Biotechnology Information Link ]
Brain EEG Modulation
Pulsed Near Infrared Transcranial and Intranasal Photobiomodulation Significantly Modulates Neural Oscillations: a pilot exploratory study
Institutes – Centre for Therapeutic Brain Intervention, Centre for Addiction and Mental Health, Toronto, Ontario, Canada
[ Published Study Link (Nature, Scientific Reports, 2019) | National Center for Biotechnology Information Link ]
Exploring the Effects of Near Infrared Light on Resting and Evoked Brain Activity in Humans Using Magnetic Resonance Imaging
Institutes – University of Sydney
[ Published Study Link (Elsevier, December 2019) ]
Modulation of cortical oscillations using 10hz near-infrared transcranial and intranasal photobiomodulation: a randomized sham-controlled crossover study
[ Abstract Text Link (Brain Stimulation Journal, December 2021) ]
PTSD and Gulf War Illness
Improvements in Gulf War Illness Symptoms After Near-Infrared Transcranial and Intranasal Photobiomodulation: Two Case Reports
Institutes – University of California San Francisco & the Veterans Affairs USA
[ Published Study Link (Military Medicine, 184, 9/10:5, 2019) ]
Selective photobiomodulation for emotion regulation: penetration study
Harvard Psychiatry Department, Harvard Medical School : [ Link ]
Red and NIR light dosimetry in the human deep brain
Institute of Chemical Sciences and Engineering, Switzerland : [ Link 1 ]
Photon Penetration Depth in Human Brains
The University of Southern California : [ Link ]
Monte Carlo analysis of the enhanced transcranial penetration using distributed near-infrared emitter array.
Institute of Biomedical Engineering, Chinese Academy of Medical Science : [ Link ]
Transcranial Red and Near Infrared Light Penetration in Cadavers
State University of New York Downstate Medical Center : [ Link ]
Quantitative analysis of transcranial and intraparenchymal light penetration in human cadaver brain tissue
Oregon Health and Science University : [ Link 1 ]
Photobiomodulation Directly Benefits Primary Neurons Functionally Inactivated by Toxins
Medical College of Wisconsin : [ Link ]
Neuroprotective effects of photobiomodulation : Evidence from assembly/disassembly of the Cytoskeleton
University of Sydney : [ Link ]
Photobiomodulation – mitochondrial ROS generation and calcium increase in neuronal synapses.
A novel method of applying NIR light intracranially, impact on dopaminergic cell survival
University of Sydney, CEA-Leti : [ Link ]
Lin-Kou Medical Center, Taiwan : [ Link ]
Infrared neural stimulation and functional recruitment of the peripheral Nerve
Department of Biomedical Engineering, Case Western Reserve University : [ Link ]
Effect of Transcranial Low-Level Light Therapy vs Sham Therapy Among Patients With Moderate Traumatic Brain Injury
Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston : [ Link ]
Brain Photobiomodulation Therapy: a Narrative Review
Department of Medical Physics, Tabriz University of Medical Sciences : [ Link ]
Psychological benefits with near infrared light to the forehead: a pilot study on depression
The Department of Psychiatry, Harvard Medical School and the Laboratory for Psychiatric Biostatistics, McLean Hospital : [ Link ]
Cognitive Enhancement by Transcranial Photobiomodulation Is Associated With Cerebrovascular Oxygenation of the Prefrontal Cortex
Department of Psychology, Institute for Neuroscience, University of Texas : [ Link ]
Mitochondrial Dysfunction-Near-Infrared Photobiomodulation as a Potential Therapeutic Strategy
Department of Research, National Neuroscience Institute, Singapore : [ Link ]
Transcranial Photobiomodulation For The Management Of Depression: Current Perspectives
Department of Psychiatry, NYU Langone School of Medicine, New York, NY, USA : [ Link ]
Increased Functional Connectivity Within Intrinsic Neural Networks in Chronic Stroke Following Treatment With Red/Near-Infrared Transcranial Photobiomodulation
Boston University School of Medicine, Harvard Medical School : [ Link ]
Review of transcranial photobiomodulation for major depressive disorder: targeting brain metabolism, inflammation, oxidative stress, and neurogenesis
Wellman Center for Photomedicine, Massachusetts General Hospital : [ Link ]
Shining light on the head : Photobiomodulation for brain disorders
Wellman Center for Photomedicine, Massachusetts General Hospital : [ Link ]
Improved cognitive function after transcranial, light-emitting diode treatments in chronic, traumatic brain injury: two case reports
Boston University, School of Medicine : [ Link ]
Augmentation of cognitive brain functions with transcranial lasers
Department of Psychology and Institute for Neuroscience, University of Texas : [ Link ]
Neurological and psychological applications of transcranial lasers and LEDs
Department of Neurology and Neurotherapeutics, University of Texas : [ Link ]