In our attempt to help many interested in the subject of photobiomodulation therapy and the science behind it, we asked two well-respected scientists and researchers to join us. They kindly agreed to participate in a photobiomodulation therapy discussion and even dived into its applications, including transcranial photbiomodulation. They offered their unique takes on this interesting and promising subject matter. To facilitate this discussion, we came up with three very straight-forward questions for them to answer.


1: What is photobiomodulation in general, and what is transcranial photobiomodulation specifically?

2: Based on your research work, what do you view as the most promising areas for photobiomodulation applications?

3: Why have you chosen those areas of research, and what could be the potential benefits of photobiomodulation in those areas?

It was our intention to cover the subject of photobiomodulation more holistically and to offer a deeper and wider perspective on it. At the same time we asked our subject matter experts to keep their answers to a more popular format, as much as possible. Thus, the three questions helped us to engage our guests into an intriguing photbiomodulation therapy discussion.


Our guests for this blog post are Prof. Michael Hamblin, Ph.D and Prof. Jay Sanguinetti, Ph.D. Prof. Hamblin is a retired Principal Investigator at the Wellman Center for Photomedicine at Massachusetts General Hospital, an Associate Professor of Dermatology at Harvard Medical School and a member of the Affiliated Faculty of Harvard-MIT Division of Health Science and Technology. Prof. Sanguinetti is Research Assistant Professor and Head of the NICE lab (Non-Invasive Cognitive Enhancement) at the University of New Mexico. Both guests are talented and prolific researchers with impressive resumes and significant accomplishments.

Perhaps, the generational gap is the major difference between these two men of science. Prof. Hamblin has recently retired after a long and prolific career in science, research and teaching. However, he carries on with his research and continues to add more scientific papers to the body of those numerous which he has already published. On the other hand, Prof. Sangunetti belongs to a younger generation. The body of his research work is growing and gaining momentum and attention. Earlier this year, he gave a presentation at the TEDx Talks.

Now that our guests are introduced, let us get to an exciting photobiomodulation therapy discussion and their thoughts on the subject of what photobiomodualtion is, does and could do in the future.

Michael Hamblin 

Michael HamblinMichael Hamblin gets the first go at this. In his answers to our three question, Dr. Hamblin offered the following thoughts and insights based on his long and prolific career as a researcher and scientist.

Brief photobiomodulation history and definition

Photobiomodulation is the broad term applied to the therapeutic use of light at wavelengths and power levels that do not cause any damage to the tissue. In actual fact, the therapeutic benefits of light have been recognized for over one hundred years. In the early 1900s after the invention of the electric light bulb, electric light baths became popular to treat a wide range of diseases. Next came heliotherapy or the therapeutic use of sunlight, and clinics were constructed in mountainous areas to expose people to the sun. In the 1960s with the invention of the laser, low-level laser therapy (LLLT) became the next method to apply light to the body. Since the recent availability of LED devices, these have now become the method of choice to apply photobiomodulation. This shift happened due to the LED’s low cost, safety, and suitability for home use.

Due to the optical properties of tissue, red and near-infrared wavelengths are considered to be optimum for penetration into tissue. Nevertheless, blue, green and yellow light are still being investigated. Scientists are actively investigating the mechanisms of action of photobiomodulation at molecular, cellular, and tissue levels and new discoveries are still being made.

Transcranial Photobiomodulation

Transcranial photobiomodulation (tPBM) describes the application of light to the head for a diverse range of brain disorders. LEDs are often employed to shine light onto the forehead, where there is no hair. Others use lasers because, they claim, they penetrate better through the scalp and skull. One of the hottest areas of debate is to what extent the light needs to penetrate into the actual brain tissue to be effective and to what extent there is a systemic effect based on light absorption by intervening tissues, or, indeed, by the whole body.

Benefits and application of transcranial photobiomodulation

Photobiomdulation for the brain is the most promising area because it could be beneficial for such a wide range of disorders.

Traumatic Brain Damage

The first group is traumatic brain damage. This can be caused by head injuries, strokes, or brain deprivation of oxygen after a heart attack or perinatal difficulties.

Degenerative Brain Disorders

The second group is degenerative brain disorders such as Alzheimer’s, Parkinson’s, Huntington’s diseases, various forms of dementia, different viral infections, toxicity from chemotherapy or heavy metals.

Psychiatric Disorders

The third group is psychiatric disorders such as major depression, anxiety, insomnia, autism, and addiction.

Cognitive Enhancement

The fourth group is cognitive enhancement for aging individuals and even young healthy persons.

Benefits of Photobiomodulation

The potential benefits of photobiomodulation (PBM) are many and various. PBM has been shown to increase cerebral blood flow and oxygenation, which are decreased in nearly all brain disorders. Moreover, brain mitochondria are stimulated increasing the vital energy source for cells called adenosine triphosphate or ATP. PBM decreases inflammation.

Neuroinflammation is involved in the majority of brain diseases together with oxidative stress, which is also reduced by PBM. PBM increases the formation of new brain cells by stimulating neural stem cells. Furthermore, it can also stimulate the formation of new connections between existing brain cells. Finally, photobiomodulation can help to clear plaques formed from aggregated protein within the brain such as beta amyloid in Alzheimer’s.

Jay Sanguinetti joins us for his take on the subject of photobiomodulation. This is Prof. Sanguinetti’s second appearence on our blog. Originally we interviewed him in March. We called the blog post with our discussion “Jay Sanguinetti’s Research in tPBM, Non-invasive Treatment Modalities and Meditation“. You can read that blog post following this link.

Jay Sanguinetti 

What is photobiomodulation: photophysical and photochemical events

Jay SanguinettiOver the past 40 years, researchers have shown that light in the visible or near infrared spectrum stimulates, regenerates, or heals physiological systems. Non-thermal and non-ionizing light elicits photophysical and photochemical events on biological tissues that have been relatively well-defined. This phenomenon, termed photobiomodulation, has led to therapeutic interventions in many domains. For example, photobiomodulation therapy reduces inflammation, pain perception, and enhances wound healing. Of course, if cells in the body respond positively to light, then cells in the brain may also be influenced by photobiomodulation.

In the past decade, researchers have begun showing that light can penetrate the skull to positively impact brain function. This method is called transcranial photobiomodulation (tPBM), and it has exciting possibilities. Thus, tPBM can be used as both a tool to study brain function, as well as a therapeutic intervention for brain diseases.

Photobiomodulation Applications: direction and promise

There are so many interesting directions for photobiomodulation. The therapeutic effects on the body are widespread. One interesting area is sports medicine. Light therapy enhances muscle repair and many athletes are beginning to see benefits of using light to help with recovery. You can image the athlete of the future with a light device at their home to assist in recovery from injury. However, my main interest in photobiomodulation is in brain health. We are facing an epidemic with the aging baby-boomer population. Between now and 2050, there will be almost 30 million “boomers” with Alzheimer’s disease, and we currently have no reliable treatments.

Several interesting studies are suggesting that photobiomodulation may be a potential intervention for this devastating disease. The idea is that near-infrared light (NIR) can stimulate some of the natural healing and regenerating processes in neurons. Furthermore, the same applies to the neuron support cells. Hence, the NIR helps the brain clean out the beta-amyloid plaques, reduces inflammation and helps the brain fight the disease.  This is truly exciting, and I hope to launch my own study with photobiomodulation and Alzheimer’s Disease soon.

benefits of photobiomodulationBenefits of Photobiomodulation for Mindfulness

Our research focuses on using neurotechnology to enhance mindfulness training. Mindfulness has many health and cognitive benefits. Thus, we hope to find a way to accelerate the acquisition of mindfulness skills, so those health benefits can scale. Furthermore, mindfulness is a powerful intervention for many neurological and psychiatric disorders. For example, mindfulness is a potential intervention for addiction. We are currently working on a paradigm to combine photobiomodulation with mindfulness in order to help patients learn the mindfulness skills quicker. We already know that photobiomodulation can enhance working-memory, and we can learn from previous experiments. If photobiomodulation can help patients learn mindfulness skills quicker with a wearable photobiomodulation technology, then we have the potential to reduce suffering on a large scale. This is truly exciting.

Photobiomodulation is a safe, effective, and relatively inexpensive technology. Many of the diseases of the brain are hard to treat, because the brain is such a complex system. It is also difficult to directly modulate brain function. Photobiomodulation offers a potentially powerful technology to restore brain function and to selectively modulation brain activity. Almost all neurological and psychiatric disorders of the brain involve inflammation. Photobiomodulation may reduce brain inflammation, which means that it could be beneficial for many brain disorders. Importantly, the intervention, using photbiomodulation, can be done at home, which means that the technology could scale easily. This is truly exciting since many of the brain interventions must be applied in a doctor’s office under supervision, which is cost prohibitive for many patients.

In Conclusion

We thought that it would be very fitting to end this blog post with a very brief video clip of an interview with another scientists, Dr. Jeffrey Knight, PhD. In this short video Dr. Knight, a clinical neuropsychologist, speaks about photobiomodulation, its effects and about how to assess the benefits of transcranial photobimodulation. Take a look.

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