Category Light and health

The Healing of Light

The healing effects of light have been used for thousands of years, starting with the use of natural light to strengthen the body and treat disease, and then expanding with the discovery of the visible spectrum and later the ultraviolet and infrared spectra.

Today, the healing effects of light cover a wide range of medical fields including neonatal jaundice, cosmetic skin care, depression and cancer treatment for people of all ages. According to Wikipedia, light therapy refers to the use of daylight or light of a specific wavelength as a source of light to prevent disease and promote healing.

Light therapy is based on the theory that biological tissues absorb light energy and convert it into thermal and chemical energy, resulting in a chain of chemical reactions in the body.

The physical and chemical effects of light specifically include thermal, photochemical, photoelectric and fluorescent effects, and different effects will have different effects on the body. The effect of phototherapy is mainly related to the wavelength, irradiation dose and irradiation mode, using various colors of photons to produce different photochemical reactions on the body to achieve the purpose of wound treatment and beauty.

In phototherapy, the different characteristics of each wavelength of light can be used to target the effect. Among them, infrared light and red light have significant photothermal effects, which can raise the tissue temperature, promote blood circulation and accelerate wound healing, thus being able to promote blood circulation and accelerate wound healing.

The photochemical effect of blue light has a wide range of applications: firstly, blue light can treat neonatal jaundice because it has the strongest hydrolysis effect on bilirubin; secondly, blue light can have a photochemical biological reaction with the porphyrins in Propionibacterium acnes, thus improving acne; in addition, because the retina-hypothalamus bundle is most sensitive to blue light, blue light is also closely related to rhythm regulation is closely related.

Violet light and ultraviolet light are more energetic and can cause photochemical reactions in cellular molecules, such as photolytic effect, photochemical effect, photopolymerization and photosensitization, and thus have anti-inflammatory, analgesic and skeletal disease treatment effects.

As an emerging effective treatment, phototherapy has many advantages over pharmacological treatment.

(1) Safety: Adequate research at home and abroad has shown that the irradiation of various colors of light on the body or cells will only have certain effects on abnormal tissue cells and will not have adverse effects on normal tissue cells. Therefore, as a non-pharmacological means, light therapy has small side effects, no residue in the body, and no after-effects.

(2) Extensive: Due to the rich physicochemical effects of light, the field of phototherapy involves all aspects of medical fields such as oncology, psychiatry, orthopedics, and medical aesthetics.

(3) Low invasiveness: In the treatment process for skin diseases mostly use extracorporeal irradiation, while photodynamic therapy mostly puncture needles, optical fiber, endoscopy and other interventional techniques to guide the light source deep into the body for treatment. Compared with surgery, phototherapy can be non-invasive or minimally invasive, minimizing the trauma and pain of patients.

(4) High selectivity: In phototherapy, the light source, wavelength and dose can be selected by targeting germs, tumors and other attack targets to achieve the effect of precise action without damaging other tissues.

(5) Highly adjuvant: Phototherapy can be combined with various treatments such as surgery and drugs; it can also be used to treat insomnia, using blue light and melatonin to work together for better results.

1

Light for repair

Infrared light for wound healing

For wounds such as burns, ulcers, and surgical procedures, the body’s natural growth is slow to heal and there is a risk of wound infection, so infrared or red light is often used in medical treatment to accelerate wound healing.

Because of its excellent healing effect and minimal side effects, light therapy can speed up recovery and reduce patient pain, and is therefore used in a wide range of applications and for people of all ages, such as post-cesarean section, post-neonatal surgery, severe burns, chronic ulcers, hemorrhoids, etc.

The mechanism of restorative light therapy makes use of the fact that red light and infrared light can pass through the skin and directly produce thermal effects on muscles and subcutaneous tissues: on the one hand, it can accelerate the circulation of blood substances and the absorption of inter-tissue fluids, which helps to keep the wound surface dry, thus reducing the survival of microorganisms and the occurrence of infections; on the other hand, it can accelerate the metabolism of ecological tissues and enhance the self-healing ability of wounds. In addition, infrared light can also reduce the excitability of nerves and provide pain relief.

In practical application, the ratio of each wavelength component is very important. Infrared rays used in light therapy can be divided into short- and medium-wave infrared rays and long-wave infrared rays. The penetration of long-wave infrared light is relatively weak and is mostly absorbed by the surface skin; the penetration of short- and medium-wave infrared light is the strongest and can directly heat the deep muscle and blood vessel tissues, and the therapeutic effect is also better. Therefore, the ratio of short and medium wave infrared rays is one of the important factors affecting the effect of restorative light therapy.

2

The Light of Beauty

Light and skin care beauty

The application of light therapy in the field of skin care and beauty can be divided into two categories: ultraviolet light for the treatment of skin diseases and visible light for acne and skin rejuvenation.

Red light irradiation with a wavelength of about 650nm can increase the level of cellular mitochondrial metabolism and promote collagen formation, making it substantially higher than the amount produced by normal cell differentiation in the human body.

And yellow light with a wavelength of about 580nm can enhance the activity of skin collagen cells, promote collagen synthesis, and strengthen collagen and elastic fibers in the skin, so it can be used for skin whitening.

As for blue light at around 415nm, domestic and foreign clinical experimental research shows that it can effectively kill Propionibacterium acnes and also reduce the number of acne and inflammatory lesions, promote tissue repair and improve skin quality.

Light therapy is not only a cosmetic treatment, but also a solution to the “hair loss” problem that many people suffer from. Red or near-infrared lasers have the ability to promote tissue repair and regeneration, promote intracellular energy transfer and circulation, increase nutrients to the hair follicle, and stimulate new hair growth.

3

The Light of Listening

Optical Cochlear Implant

A cochlear implant is a biomedical device that converts sound waves into electrical signals, which are then sent to auditory processing nerve cells. A team of researchers at the University ofGöttingen Medical Center has combined LED and genetic manipulation to create an optical cochlear implant that successfully restores sound perception to deaf people, replacing electronic electrodes with optical fibers and electric currents to activate cochlear auditory neurons, and solving the problems of resolution and clarity of the traditional cochlear sound signal.

Photodynamic Therapy (PDT) is a new method of treatment with photosensitive drugs and laser activation, with the outstanding advantages of being precise, targeted, less invasive, and repeatable. The three necessary elements are photosensitizer, light source and oxygen molecules in the cells, and the choice of photosensitizer and wavelength of light is the key to photodynamic therapy. The selection of photoreceptors and wavelengths is the key to photodynamic therapy.

4

Light of Life

Optogenetic

Optogenetic (optical genetics) is a discipline born in 2005 that combines optics, software control, genetic manipulation, electrophysiology and other technological frontiers of crossover bioengineering.

Optogenetics holds promise for restoring memory in Alzheimer’s patients, and for treating Parkinson’s disease, narcolepsy, depression, and anxiety. Optogenetic technology tools bring a revolutionary boost in neuroscience and cell biology signaling pathway research. Optogenetic technology precisely controls the activity of specific cells in space and time, especially in time with millisecond precision, with a wide range of potential applications, even covering diseases in our overall life stage from birth to aging, and its ambition to benefit human health is just around the corner.

Rotate the life clock-natural light and human biorhythms

In 1972, scientists identified the Suprachiasmatic Nucleus (SCN) in the hypothalamus as the central biological clock that coordinates circadian rhythms in mammals by destroying neural tissue. It is responsible for sensing the changes of light in the external world and transmitting the time information of light to the peripheral organs in the form of hormones and signals from the autonomic nervous system, and keeping the Peripheral Clock of the whole body in the same rhythm as the Central Clock for the healthy functioning of the human organism.

The light and dark changes of the sun are the most powerful influences on the endogenous rhythm of life. The circadian rhythm, with a cycle close to 24 hours, is involved in regulating many important physiological processes in the human body, controlling the daily cycle of sleep, waking, eating, body temperature, hormone secretion, metabolism and other physiological activities.

The daily variation of the light and dark cycle of natural light is the most important timing factor of biological rhythm, and the variation of the intensity and time of sunlight stimulation in the early morning and evening of different seasons also affects the biological rhythm and makes human physical and mental health show seasonal correlation.

For example, the early sunrise and high intensity of sunlight in summer make the circadian phase of human body earlier than other seasons, and even under the same indoor temperature, human body sleeps shorter and wakes up earlier in summer than other seasons.

Seasonal Affective Disorder (SAD) strikes at the same time every year, starting in late fall/early winter and ending in late spring/early summer, and is more prevalent in high latitudes where seasonal changes are evident.

Obesity, many cancers, neurodegenerative pathologies, and psychiatric disorders are all highly associated with rhythm disorders. The results of two U.S. clinical trials have shown that rhythm disorders seriously disrupt the dynamic balance of glucose levels in the body, affecting the regulatory effects of insulin and appetite control.

Therefore, people should learn to pay attention to the interaction mechanism between biological rhythms and human health while they are busy, follow the natural circadian rhythm, choose a healthy lifestyle, enjoy the sunlight during the day, experience the darkness at night, and work and rest with the sun.

In 2017, three geneticists from the United States, Jeffrey Hall, Michael Rosbash and Michael Young, were awarded the Nobel Prize in Physiology or Medicine for ”discovering the molecular mechanisms that control circadian rhythms.” They isolated from Drosophila a specific set of genes, named Period gene, whose mRNA and protein levels vary in a circadian rhythm, with lower concentrations during the day and higher concentrations at night. Through further in-depth study, they discovered more genes related to biological clocks and their production and operation mechanisms. This is an explanation of biological rhythms from a genetic perspective.

Exploring light and emotions

The second half of the 20th century witnessed a major shift in the spectrum of human diseases. With the advancement of medical technology and changes in population structure, lifestyle, and living environment, the incidence of infectious and malnutrition diseases declined dramatically, while the prevalence of chronic non-communicable diseases such as cardiovascular diseases, cancer, mood disorders, Alzheimer’s disease, and psychosomatic diseases increased dramatically, becoming the most potent enemy threatening human health and life.

In the 21st century, “disease medicine” is transformed into “health medicine”, and the prevention and treatment of human diseases and health protection are developing in a diversified way, and the medical model of “biology, psychology and society” has emerged. The “bio-psycho-social” model of medicine has emerged.

In 1943, James Halliday, an American physician, introduced the concept of psychosomatic illness and emphasized that psychological factors can cause illness.

and his book “Illness from the Heart

In his book “How to Live 365 Days a Year”, John A. Schindler, a practicing American physician, states that up to 76% of illnesses are related to bad emotions (in this case, hidden underlying emotions).

Not only do chronic bad moods lead to mental illness or psychological disorders, but they also cause negative reactions in the nervous and endocrine systems, leading to organic pathologies and functional disorders. For example, the human gastrointestinal tract is known as the palette of emotions, anxiety, depression, anger and other negative emotions may affect the gastrointestinal function, causing symptoms such as diarrhea and stomach pain. Stomach ulcers and duodenal ulcers are the most typical psychosomatic diseases. Through reasonable methods to regulate emotions and maintain an optimistic and positive state of mind is an important means to prevent and treat diseases and promote physical and mental health.

Light has significant emotional intervention effects through visual and non-visual effects, and also affects the cognitive processing of the brain such as memory, attention and decision making, and has health effects that should not be underestimated.

Emotion is an extremely complex psychophysiological phenomenon, reflecting the interaction between human subjective consciousness and cognition, the inner biological nervous system and the external environment. Since the time of ancient Greek civilization, humans have been tirelessly exploring the mystery of emotions, explaining them from different disciplinary perspectives, defining and classifying them. Nowadays, emotions are not only an important object of psychological research, but also an international frontier and a hot issue in multidisciplinary research.

Charles Robert Darwin, in The Expression of Emotion in Man and Animals, discusses the biological basis of emotions and emphasizes the role of the environment on emotional behavior. James Lange argues that stimuli trigger activity in the autonomic nervous system, producing changes in physiological states, and that emotions are the product of this process.

Cannon Bard asserts that the thalamus is the center of emotional activity, producing emotions of specialized nature attached to simple sensations when signals travel directly from the receptors or down from the cortex to the thalamus. When people are confronted with the same stimulus situation, individuals will have different emotional responses due to the different estimation and evaluation of the situation. Stanley Schachter and Jerome E. Singer proposed that individuals experience high levels of physiological arousal such as increased heart rate, stomach contractions, and shortness of breath, as well as individuals’ cognitive arousal to changes in physiological states are two necessary factors for the production of specific emotions.

It can be said that emotional states are the result of the integration of cognitive processes (expectations), physiological states and environmental factors in the cerebral cortex. In addition, Magda B. Arnold’s doctrine of “rated arousal”, James Papez’s agonistic circuit, Carroll Ellis Izard’s “motivational differentiation”, and many others have been proposed for emotional states. Izard’s “Motivation I Differentiation” and many other accounts of emotion generation.

The American psychologist Paul Ekman defined six basic human emotions: anger, disgust, fear, pleasure, sadness, and surprise. Like the three primary colors mixing to create multiple colors, the basic emotions combine with each other to derive a variety of compound emotions such as tension, anxiety and depression. The human inner world is so rich and subtle that it is beyond the scope of language to elucidate.

Emotional dimensional models have been gradually developed to represent the relationship between various emotions, to explain human emotions, and to describe emotional states. Wilhelm Wundt was the first to explicitly propose the Emotional Dimension theory, which states that emotions consist of three dimensions: “pleasant and unpleasant, excited and calm, and tense and relaxed”. Each specific emotion is located in a different position between the three dimensions and the two poles.

R. Piutchik, an American psychologist, believed that emotions consist of three dimensions: intensity, similarity, and bipolarity, and used an inverted cone to describe the relationship between the three dimensions of emotions. Charles E. Osgood’s study evaluated emotional experience in terms of three dimensions: evaluation, intensity, and activeness.

Albert Mehrabian and James A. Russell proposed the PAD three-dimensional emotion model in 1974, based on this idea that emotions possess three dimensions: Pleasure, Activation and Dominance:

P is Pleasure-Displeasure, which represents the positive and negative characteristics of an individual’s emotional state.

A is Arousal-Nonarousal, which indicates the level of neurophysiological activation of the individual

D is dominance-submissiveness

(Dominance-Submissiveness), which indicates the individual’s state of control over situations and others

It is used to indicate whether the emotion is subjective or influenced by the objective environment.

Specific emotions can be represented by the values of these three dimensions in spatial coordinates, with the values on each dimension ranging from -1 to +1, +1 indicating a high value on this dimension and -1 indicating a low value on this dimension called PAD.

Once upon a time, the study of emotions was quite difficult, and animal experiments could understand the emotional reflexes and neural projections of animals in real time, but the emotional responses of lower animals may be quite different from human emotions. The development of advanced nondestructive neuroimaging techniques, including brain waves and magnetic resonance functional imaging, provides avenues to explore emotional brain mechanisms.

Since the 1980s, numerous studies have shown that circuits in the brain control people’s emotions, integrate and process emotional information, and produce emotional behaviors. 1952, Panl D. MacLean formally introduced the term Limbic System, which consists of a series of neural clusters and the cerebral cortex, including the cingulate gyrus, hippocampal gyrus, amygdala, and septum, The limbic system is composed of a series of neural clusters and the cerebral cortex, including the cingulate gyrus, hippocampal gyrus, amygdala, septum, hypothalamus, and papillae. The amygdala is the key nucleus for emotional processing.

Research suggests that the amygdala is likely the body’s emotional integration center, integrating and projecting sensory information to the cortex, hypothalamus and brainstem nuclei to form emotions at the conscious level as well as somatic and visceral emotional responses. Recognition and expression of negative emotions such as fear and depression, perception of emotional faces, and emotional memory are all associated with the amygdala. The hypothalamus has an extremely important role in emotion regulation; it is the highest center under the vegetative nerve cortex, an important point of contact for the limbic system, the reticular formation.

The hippocampus is responsible for learning and memory and is also involved in emotion regulation. Conducting research on emotional brain mechanisms is necessary and urgent, and will help people explore the emotional healing effects of light in a more informed and systematic way, so that they can develop healthier light strategies with more practical effects.

Human-centered light environment design

The study of light environment was born out of human needs, and human pursuit of light has driven the continuous development and innovation of lighting and daylight utilization technology.

With the gradual clarification of human physiological and psychological response mechanisms to light environment stimuli, the health benefits of light in various aspects of “vision, rhythm and emotion” have been continuously discovered, and human factors lighting-related research, design and application projects have emerged in large numbers, and gradually from the study of human capabilities and limits of availability to a comprehensive focus on human physiological and psychological needs The research, design, and application projects related to human factors lighting have been proliferated, and gradually expanded from usability research on human capabilities and limits to comprehensive research on human physiological and psychological needs.

In 2016, the European Lighting Association released its 10-year strategic roadmap, which puts forward the core development concept of “human-centered lighting” and confirms the strategy to improve the quality of lighting through LED products, intelligent lighting systems, as well as human-centered lighting and circular economy to make it a new driver of growth in the European lighting market, and will develop policies to Support the development of human factors lighting-related industries.

Taiwan’s Industrial Technology Research Institute (ITRI) has set up the LED Human Factors Lighting Laboratory and conducted research projects such as “LED Intelligent Human Factors Lighting Research to Improve Work Performance” and “High Value LED Human Factors Lighting Research for Healthy Home Lighting at Night”, and released the “LED indoor human factors lighting system and Android body remote control system composite human factors intelligent light environment system” and other application products.

Technology will eventually return to people-oriented and focus on human health and well-being, and human factors engineering will also lead the future of light health research and practice.

People read in dim light or shadow, write on strongly reflective paper, and work in front of a high-brightness electronic screen …… These ergonomic lighting will cause eye fatigue, blurred vision, headaches and general discomfort, resulting in reduced operational performance, mental alertness and many other problems.

Long-term flicker, unsuitable illumination, uneven light distribution, strobe, glare light environment, will produce visual damage and other more serious consequences. It can be seen that ergonomics in the design of the light environment can not be ignored.

Systematic thinking is the beauty of ergonomics. Ergonomics in the light environment is a comprehensive study that takes into account visual characteristics, operational tasks, environmental conditions and the coordination between them. The purpose is to make people easily and accurately identify visual targets, complete visual tasks with high performance, create a light environment that meets maximum comfort while protecting visual health, and avoid physical damage caused by poor lighting conditions to ensure safety.

Smart lighting will become more common in the future, and the diverse ways of interaction between people and the light environment and its luminous interface have become the key elements of light health human factors research.