Light Overview, and Summary of Biological Interactions
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
Evolution of Humans with Light, and current state:
Current State Of Light
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?
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.
- 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. 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.
- 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.
- 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.
- 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.