How RLT Works

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Light Overview, and Summary of Biological Interactions

So what is light, and how does it interact with our bodies, any why now are we hearing about it? Well, there’s a lot of varying discussions taking place around humans and how we’ve evolved, and what techniques are available for treatment, and what is most effective to helping our species continue to evolve and improve our total well being. One of the foremost authorities on this topic, Michael Hamblin, covers the topic on Why Humans Need Sunlight to Be Healthy: “LLLT/PBM (photobiomodulation) is more than an alternative kind of medical treatment; it is a whole new method to control cellular processes and modulate living organisms by precise alterations in the chemistry of biomolecules.

PBM enables the contemporary clinician or therapist who holds a modern and multidisciplinary outlook to fight against diseases and other disorders in both humans and other animals. Moreover, it is a possible way to stimulate or inhibit many different biological processes that occur in most (if not all) different living creatures. It could even be suggested that the photobiomodulation phenomenon is as old as life itself!” 4 – Michael Hamblin

So if we take a step back, and look through recent times and the medical journey, the knowledge that plants convert sunlight into energy has only been around for the past 200 years or so, and as science and technology have improved, so has the study of photosynthesis. When scientists first began to understand what was occurring in plants the methods used to reach their findings were unsophisticated. Experiments involved watching plants in jars and taking notes; they didn’t have access to the tools scientists have now. Humans too react to certain wavelengths of light, but until now, we haven’t had the tools to reveal the importance of this interaction. We’re now witnessing the convergence of science and technology allowing us to understand, at a molecular level, what is happening when specific wavelengths of light interact with our biology. This is Light Therapy or Photobiomodulation which is the study of how light interacts with human biology. With this fresh information, the ability for clinicians and therapists to fight disease and heal their patients is expanding.
Technically speaking, just as cells need oxygen from the air we breathe and nutrients from the food we eat to function, we’re now learning that light is also necessary for healthy cell function. Specific wavelengths of light power our cells, influence our moods, interact with our cognitive function, and promote healing in a broad spectrum of applications. By harnessing specific wavelengths of light, we can optimize our biology and improve a vast variety of ailments that previously were never associated with light exposure.

Evolution of Humans with Light, and current state:

It turns out that light is an essential nutrient for humans and our health depends on getting the right dose of five specific types of light. We’re talking about light, but “light” is electromagnetic radiation. What we call light are just the wavelengths of the spectrum that we can perceive with the limits of our human biology. Other portions of the spectrum have wavelengths too large or too small and energetic for our human senses to detect.
To help accentuate this point, when electromagnetic radiation passes through a prism, the wavelengths separate into colors, each color determined by a different wavelength with violet having the shortest wavelength and red with the longest. Until very recently, it wasn’t known that the different colors of the electromagnetic field interact with our bodies in unique ways and are directly correlated to our health and wellness. Some wavelengths produce positive effects like tissue repair yet some, like Blue Light from computer screens and smartphones, increase the occurrence of migraines and diminish sleep quality.
The first humans spent much of their time outdoors where they naturally benefited from the exposure to light. As modern “advanced” humans started to spend less and less time outdoors, the health of our species has suffered as a result. Chronic stress, depression, and anxiety disorders are just a few of the unfortunate ramifications of harnessing the power of the sun in an electric light bulb. Our lives are no longer limited by daylight. We can work more and sleep less. Unintentionally, our technological achievements have caused an imbalance in our exposure to specific wavelengths, for example, over-exposure to blue light, resulting in imbalances in our wellbeing. The point is that modern humans are deficient in the benefits of all of these five wavelengths of light, and there are health consequences when we don’t get enough.
As the reliance on artificial light increased, our homes, offices, and indoor environments all received similar lighting solutions, all using similar wavelengths of light. Without an understanding of the importance of wavelengths, many lighting companies primarily focused on blue and white lights, as these light were thought to most closely mimic real sun light. Mostly what they were experiencing was bright blue light. It’s now believed that more than 90% of a human’s life is spent under artificial light. Our exposure to light is imbalanced and so too are our bodies. Most of us are deficient in many of the wavelengths needed to promote healthy biology. As we learn more about how specific wavelengths of light interact with the body, and understand the types of lights that we are predominantly exposed to, it’s clear that humans are deficient in Red & Near-Infrared Light wavelengths.
There’s something about being in the sun that translates to a general state of well-being. It’s pretty rare for a person to spend the day at the beach and not feel great because of it. Doctor’s once prescribed their patients trips to the seashore to treat tuberculosis and other ailments. We need the sun to be healthy. Specifically, the human body needs a balance of all wavelengths to function optimally. And with our recent imbalance of light exposure, it's more important than ever that humans get an increase in Red & Near-Infrared Light to improve their general wellness.
As we mentioned before, in the past our ancestors' lifestyles allowed for proper light exposure. Getting the right dose of a variety of wavelengths was never something that needed to be discussed. Humans worked, played, and communed with others in natural light that contained the full spectrum of wavelengths needed for their biology to be optimized consistently. They faced other health challenges of course, but as we’ve advanced in our knowledge of sanitation and medicine, we lost our connection to the sun. We’re living in a time of amazing technological advancements yet it's just now becoming common knowledge that we can improve our biology through proper light exposure.
Red and near-infrared light have profound effects on our cellular and molecular health. And we’re designed to need ample amounts of those types of light to have optimal health. The vastness of this subject may be complicated to understand, but it is becoming common knowledge, with recent advancements in science and technology, that all wavelengths interact with the human body in a variety of ways and the human body needs light to be healthy. These two specific wavelengths have a multitude of positive effects on the body.

Current State Of Light

Since Post World War II, we’ve seen amazing advancements in not only our way of life, but how we care for the sick or aging. The use of antibiotics became prevalent and the pharmaceutical industry gained influence and power. The science-boosting competition of the cold war combined with increased understanding of biology and chemistry and the implementation of Ford's assembly line methods enabled mass production of drugs and produced a ‘golden age’ of drug development during the post-war boom, and the term “Better Living through Chemistry” was born. Since this time, we’ve moved to believing that anything in pill format resulted in a better result, mostly due to the immediacy of the effect. It hasn’t been until the recent few decades that we’ve witnessed the escalation of health issues that we started to rethink the methods.
What kind of health consequences? The most common light-related health problems that most people are already familiar with are vitamin D deficiency (from too little UV light) and circadian rhythm disruption (from too little blue light in the morning, and too much artificial light at night). Most people are aware of health issues like vitamin D deficiency from too little UV or circadian rhythm disruption from excess blue light before bed but these are just two light-related health issues. Improper light exposure has been linked to a variety of more serious issues including heart disease, obesity, diabetes, and cancer.
Without the ability to provide our bodies with the correct exposure to certain wavelengths of light, it’s no surprise that our species is suffering. Changes in light exposure over the past decade continue to escalate to a point of critical importance. We’re experiencing widespread damage to our brains, organs, and immune systems that correlate with insufficient light exposure. Neurodegenerative diseases like Alzheimer’s, dementia, Multiple Sclerosis, and Parkinson’s 5,6,7,8 Dozens of types of cancer 9,10,11,12 Obesity 13,14 Diabetes15 Metabolic syndrome16 Heart disease17
In recent years, artificial light exposure at night (from electronic devices like phones, TVs, computers, indoor lighting, etc.) have been linked with numerous diseases, like cancer 20,21 Depression 22 obesity, diabetes, and metabolic syndrome 23,24,25 Insomnia and poor sleep 26 Mood disorders 27.

Light, Wavelengths and our Biology

Visible Light in the Electromagnetic Spectrum:

The electromagnetic spectrum is composed of all frequencies of electromagnetic radiation that propagate energy and travel through space in the form of waves. Longer wavelengths with lower frequencies make up the radio spectrum. Shorter wavelengths with higher frequencies make up the optical spectrum. The portion of the spectrum that humans can see is called the visible spectrum.

Humans have evolved to sense a small part of the light spectrum. We know these wavelengths as “visible” light. Our eyes contain cells known as rods and cones. Pigments in those cells can interact with certain wavelengths (or photons) of light. When this happens, they create signals that travel to the brain. The brain interprets the signals from different wavelengths (or photons) as different colors.

The longest visible wavelengths are around 700 nanometers and appear red. The range of visible light ends around 400 nanometers. Those wavelengths appear violet. The whole rainbow of colors falls in between.

Light is an electromagnetic wave. White light contains waves of many different visible colors. Each color of light has a characteristic wavelength and energy.

Most of the light spectrum, however, falls outside that range. Bees, dogs and even a few people can see ultraviolet (UV) light. These are wavelengths a bit shorter than violet ones. Even those of us without UV vision can still respond to UV light, however. Our skin will redden or even burn when it encounters too much.


Of all the various wavelengths of radiation, there are the five types of bioactive light that fall within the visible light spectrum:

  • Blue light – sets the circadian rhythm in our brain, and activates different neurotransmitters and hormones.
  • UV light – helps us to synthesize vitamin D from the sun.
  • Far-infrared – acts to heat our cells, stimulating cell function and circulation.
  • Red light – interacts with mitochondria increasing cellular energy.
  • Near-infrared (NIR) – interacts with the same pathways as red light – particularly in the mitochondria – to stimulate cellular energy.

So, how does light penetrate and interact with our bodies?

While most wavelengths of light (such as UV, blue, green, and yellow light, etc.) are mostly unable to penetrate into the body and stay in the layers of the skin, near-infrared light and red light are able to reach deep into the human body (several centimeters, and close to 2 inches, in some cases) and are able to directly penetrate into the cells, tissues, blood, nerves, rods and cones of the eyes, the brain, and into the bones.
Once in those deeper tissues, red light and near-infrared (NIR) light have incredible healing effects on the cells where they can increase energy production, modulate inflammation, relieve pain, help cells regenerate faster, and much more. The key point is this: Red/NIR light are not some weird technology that benefits us for some random reason. These wavelengths of light come from the sun, and it turns out that our body has evolved over millions of years to be capable of utilizing red and near-infrared light from the sun to help power up our cells – literally enhancing the function of our mitochondria, our cellular energy generators – among many other beneficial effects.

Photobiomodulation and Biological Interactions.

Research on Red & Near-Infrared light has demonstrated an effect on a variety of pathways and molecular mechanisms. At the molecular level, the basic interactions trigger responses, leading to cellular changes and eventually resulting in tissue changes in the body.

The beauty of RLT, is that effects happen at one of the lowest biological levels – the molecular levels, which then effect our cells, and finally we see changes to our tissues/ligaments/bones and many other areas of our body. Now lets go through these from lowest level to highest.

  1. At the Molecular Levels, there are few large areas that we need to review. To oversimplify, our molecules interact with light and result in a variety of triggers and changes to things like DNA, Chromosomes, DNA Replication and Gene Expression. Here are some of the most exciting findings related to the main molecular groups that are effected:
    • The chromophore is a region in the molecule where the energy difference between two separate molecular orbitals falls within the range of the visible spectrum. In biological molecules that serve to capture or detect light energy, the chromophore is the moiety that causes a conformational change of the molecule when hit by light.  Two specific chromophores that are worth mentioning as it relates to RLT is Cytochrome c oxidase (CCO) & Channelrhodopsins (ChRs):  Cytochrome c oxidase, is a large transmembrane protein complex found in the mitochondria of eukaryotes. Certain wavelengths of light trigger events in the mitochondria via Cytochrome C Oxidase. Channelrhodopsins (ChRs), Light-sensitive ion channels that control the flow of various ions like calcium, potassium, sodium, etc. Eventually, these trigger events and expressions of genes related to protein synthesis, cell migration, and proliferation, anti-inflammatory signaling, amongst others.
    • In addition, there’s Signaling Molecules, or cell signaling or cell-cell communication, which governs the basic activities of cells and coordinates multiple-cell actions.[1] A signal is an entity that codes or conveys information. Biological processes are complex molecular interactions that involve many signals. The ability of cells to perceive and correctly respond to their microenvironment is the basis of development, tissue repair, and immunity, as well as normal tissue homeostasis. Errors in signaling interactions and cellular information processing may cause diseases such as cancer, autoimmunity, and diabetes.  A few primary signaling molecules worth mentioning are Adenosine triphosphate (ATP), which is literally cellular energy produced by mitochondria. Cyclic AMP (cAMP), an extremely important signaling molecule Involved with inflammation pathways within the cells, Reactive oxygen species (ROS), commonly called free radicals, are produced from physical exercise and signal many of the positive adaptations that our body makes in response to exercise.  And last but not least, Nitric oxide (NO).  NO levels rise after Red & Near-Infrared light exposure. NO  is involved with blood vessel dilation, but it also triggers other pathways.
    • Transcription Factors also play a major molecular role in how RLT effects the body.  Transcription factors are proteins that help turn specific genes on or off by binding to nearby DNA.Transcription factors allow cells to perform logic operations and combine different sources of information to decide whether to express a gene.  The following are effected by RLT:
      • Nuclear factor-kappa B (NF-kB): A signaling compound that regulates genes involved with inflammation
      • Receptor activator of nuclear factor kappa-B ligand (RANKL):   A transmembrane protein that is involved in activating changes to the cells that absorb bone tissue during growth and healing.
      • Protein Kinase B(Akt)/ Glycogen Synthasekinase (GSK3b)/b-catenin pathway: Helps modulate cell survival and apoptosis (programmed cell death)
      • Akt/mTOR/CyclinD1 pathway: Stimulates  rapid  cellular growth.
      • ERK/ Fork-head box protein M1 (FOXM1): Improves cell division by regulating the cell cycle as it moves through specific phases of mitosis.
      • Peroxisome proliferator-activated receptors (PPARy): Involved in the inflammatory response.
      • Runt-related transcription factor 2 (RUNX2): Involved in bone cell differentiation.
    • And finally, Effector Molecules are involved with many of the positive effects associated with RLT.  These molecules are a small molecule that selectively binds to a protein and regulates its biological activity. These molecules act as ligands that can increase or decrease enzyme activity, gene expression, or cell signaling. They can also directly regulate the activity of some mRNA molecules. A few worth mentioning are:
      • Transforming growth factor (TGF-b): Helps stimulates collagen production and inhibits degradation of the non-cellular components of tissue.
      • Vascular endothelial growth factor, which is Involved with the formation of new blood vessels.
      • Fibroblast & keratinocyte growth factor,  helps in wound healing
      • Melatonin, is increased throughout the body when RLT is used. Melatonin has critical roles in protecting the mitochondria from damage and supporting glutathione levels, one of the body’s antioxidants and detoxifying compounds.
      • Brain-derived neurotrophic factor, help with neuron/brain cell growth and regeneration.
  2. Moving to a higher biological level, we also have Cellular Mechanisms.  At the Cellular level, Lights’ interactions happen after molecular interactions occur in the organelles and nucleus. The changes result in variations to a cell’s functions and ultimately influence how cells behave in a larger network of systems. Some of the key cellular processes that have been studied in Light Therapy are:
    • IInflammation: A key cellular mechanism that Red & Near-Infrared light have are inhibition of inflammatory prostaglandin PGE2 production and expression of COX-1 & COX-2, and inhibition of the NFkB pathway.
    • Cytoprotection: Studies show Red & Near-Infrared light helps protect cells from dying after exposure to a variety of toxins like Methanol and cyanide.
    • Proliferation: Some cells have shown to grow and replicate faster with exposure to Red & Near-Infrared light.
    • Protein Synthesis: Red & Near-Infrared light can also stimulate cells to produce more proteins like collagen.
  3. As the molecular changes interact and cause a cellular change, the ultimate result is change to our biology – this is where we see how RLT affects our Tissue. For example:
    • Muscles: studies demonstrate that Red & Near-Infrared light can improve muscle performance and reduce recovery time.
    • Brain: Clinical trials Red & Near-Infrared light showed improvements in cognitive performance, improved functioning after certain brain injuries, improved mood, as well as improvements in certain neurological diseases.
    • Nerves (Pain): Red & Near-Infrared light can reduce sensation in nerve fibers.
    • Healing (Bones, Tendons, and Wounds): Red & Near-Infrared light can accelerate the healing of tendon, muscle, and ligament damage and increase proliferation and healing of bone fractures and skin wounds.
    • Hair: By increasing blood vessel dilation and anti-inflammatory responses, Red & Near-Infrared light is effective in treating hair loss and stimulating hair growth.
    • Skin: Anti Aging benefits associated with Red & Near-Infrared light include collagen production and reduction in fine lines and wrinkles.
    • Summary:
      • Positive literature describing the benefits of red and near-infrared light therapy abounds because, in our deficient state, even small increases in healthy doses of light result in dramatic results.
      • The fundamental reason that red and near-infrared light have so many incredible benefits on our health is that they are correcting a deficiency.
      • We should be getting plenty of red and near-infrared light from the sun, but since we’re not, we can apply a device in a targeted way to give us that light “nutrient,” and get profound benefits from it.
      • Near-infrared light and red light can reach deep into the human body and can directly penetrate cells, tissues, blood, nerves, rods, and cones of the eyes, the brain, and the bones. This is unique to Red & Near-Infrared wavelengths of light. Most other wavelengths of light such as UV, blue, green, and yellow light are mostly unable to penetrate the body and only stay in the top layers of the skin.

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