Giving the Green Light for Red Light Therapy

Rohan Purohit | SQ Online (2024-2025)

Saltman QuarterlyStudent
··8 min read

Light Therapy

Perhaps you have a sign at your gym offering the use of red light therapy to complement your workouts, or maybe you have seen it offered at a clinic at your local mall. You quickly think, “Wow, just another therapy that promises to fix all of my problems.” Perhaps you conclude that it is just a scam, and you wonder if it is even safe. You’re very familiar with the fact that UV radiation can cause premature aging and skin cancer, and wonder if this light radiation could be at play in these therapies. It is easy to disregard light therapy or be scared of it, but what exactly is it, how does it work, and how can it help?

How Light Therapy Works

To the immediate surprise of many, several modules of light therapy are FDA-approved, depending on the particular device and its use. An increasingly popular example of light therapy is photobiomodulation, which includes all lower-level light therapies (LLLTs). These light therapies are non-invasive, meaning that no medical instrument enters the skin or any other body opening. LLLTs utilize low-level lasers that have an output power of 500 mW and some class IV lasers that exceed 500 mW. The lower-level light therapy region is also known as the red light region and near-infrared light (NIR), which operate at wavelengths within the range of 600 nm to 1100 nm. This is the optimal light region for most light therapy because it is ideal for penetration of skin tissue, due to reduced obstruction by tissue chromophores. These chromophores include all tissues, melanin or red cell hemoglobin, that can absorb light.

What does the light do after the lasers penetrate the skin? Firstly, it is important to review the process of energy production and the benefits of exercise on our body. The energy that the human body uses to survive is in the form of molecule adenosine triphosphate, ATP, produced in our cells’ mitochondria. Exercises that require endurance have been shown to increase the mitochondrial content per gram of tissue and mitochondria composition. In other words, the total number of mitochondria, and the rate of your body’s mitochondrial metabolism, increases. The stimulation of mitochondrial development thus allows for increased ATP production, leaving more available energy for our body to use.

However, to develop this more efficient metabolism, large amounts of time and effort need to be dedicated to these endurance activities, such as an athlete’s training. Light therapy offers a shorter path to this goal. Instead of undergoing arduous endurance exercises to develop more mitochondria, light therapy increases the productivity of mitochondria currently in the body. The red light, or NIR, which has successfully bypassed all the tissue chromophores, can now act as a fuel source for the mitochondria in the process of cellular respiration. This is similar to how plants utilize photosynthesis to convert solar energy into chemical energy. Now, with these increased levels of ATP, many of the neuronal and intercellular signaling, increasing efficiency.

Light Therapy and Bone Regeneration

One of the primary physical processes in which red light and NIR therapies are used is bone regeneration and tissue repair. Many traditional solutions for severe bone loss include the use of stem cells. Mesenchymal stem cells in particular signal for the increase of osteogenic cells, by differentiating into osteoblasts, which then deposit bone to the site of regeneration. In many cases, laser therapies can boost the differentiation process of stem cells, and thus accelerate bone and tissue repair. Still, the difference lasers truly make to this process is often debated.

However, a different process clearly highlights that lasers can be used to assist in bone regeneration. In a study conducted by Abramovich-Gottlieb et al., researchers investigated the effects of LLLT upon regions of bone damage. The results showed that the quantity of osteogenic cells was much greater in the group where the therapy was employed.

Bone tissue repair and regeneration require a certain level of porosity, or the fraction of the bone’s volume which isn’t occupied by tissue, in the bone grafts. An increased porosity allows for blood vessels to be formed more easily within the area being repaired, which is essential in facilitating the high demand of blood in cases of severe bone repair. A study conducted by Sobol et al. investigated the claim that lasers can increase porosity. They found that due to the lasers, heat was able to reach areas that generally remained cold, creating a strain and impacting homeostasis within the bone tissue. When exposed to short laser pulses, this causes microbubbles to grow within the bone and thus fragments the tissue. These bubbles are formed to deal with the stress created by the laser’s heat, effectively increasing the porosity of the bone tissue. This helps activate the regeneration process, thus making the usage of lasers useful in treating intervertebral disk and joint diseases.

The Future of Light Therapy in Psychiatry

Through the above examples, the benefits of light therapy have become increasingly apparent. However, through the continued work of researchers, it has also become evident that light therapy can expand beyond these aforementioned physiological contexts and into the field of psychology. One study sought to discover the impact of near-infrared LLLT upon patients with a variety of mental conditions (including depression, PTSD, and substance abuse) when the light of the laser was shone at different areas of the forehead.

Previous studies have shown that depression can be connected with abnormalities in regional cerebral blood flow. LLLT has previously been used to treat patients with Raynaud’s phenomenon, a condition in which one experiences reduced blood flow to their hands, fingers, or other extremities. LLLTs were able to successfully increase blood flow in the hands of those with Raynaud’s phenomenon, so researchers questioned whether these lasers could be used to increase blood flow in the brains of those struggling with depression or anxiety, given the connection between regional cerebral blood flow and depression.

Their observations were based on results from the patients’ Hamilton depression rating scale (HAM-D) and Hamilton anxiety rating scale (HAM-A) before and after two weeks of treatment, both of which are one of the most widely used depression/anxiety assessment scales by clinicians. They discovered that there were significant improvements in the scores for the patients who received the NIR treatment in comparison to those who received the control. Of the ten patients, six achieved remission, or the complete disappearance of symptoms, based on their HAM-D results, and seven experienced remission based upon the HAM-A test.

Dr. Richard S. Schwartz, an associate professor of psychiatry at Harvard Medical School, emphasizes that light therapy may offer an important alternative to antidepressant medications. He claims that antidepressant medications can take several weeks before positive effects are seen, and often cause numerous side effects including nausea and weight gain. However, patients who respond positively to light therapy tend to see a reduction in their symptoms within a week, and with little to no side effects.

Since light therapy has shown great potential in this field, Mass General Hospital has implemented a Brain Photobiomodulation Clinic. They utilize PBM to assist patients with major depressive disorder, generalized anxiety disorder, and other neuropsychiatric conditions. Their work has made it clear that light therapy will be a key player in future treatments for psychiatric conditions, particularly for patients who have not experienced favorable results from more traditional treatments or struggle with its side effects.

Certainly, light therapy won’t be the end of all of your problems, but its benefits are not as limited as you may have originally expected. Bone regeneration and assistance with depression, PTSD, and substance abuse only scratch the surface of what light therapy has to offer. Numerous other research studies in the past or ongoing have found that red, and other light therapies, can help with acne, diabetes, and even conditions such as Alzheimer’s and long COVID! As the field continues to expand, and new benefits are continually discovered, you will find that these therapies can certainly play a major role in the treatment for a variety of new conditions.

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