Light and health

Urban-centric lighting is the research topic of an Urban Lighting task group. The group was formed to
carry out research about the influence of urban exterior lighting in people’s health. The Task Group is
promoted and managed by CICAT, a Spanish Cluster for innovation in the sector of lighting. The cluster
members come mainly from the lighting manufacturing industry, and also include universities, and other
related companies, including independent lighting designers.
This applied research is being carried out by technicians, planners, managers and designers from
different private companies and public institutions, with responsibility and objective markets centered
in public lighting and urban planning.

Shading due to proximity between buildings can reduce or compromise the quality of natural lighting in work environments and, consequently, impact the quality of lighting throughout the day. The objective of the research is to evaluate the photobiological parameter equivalent melanopic lux (EML) in prolonged daytime work environments, shaded by adjacent buildings. The methodology of this study foresees: simulations of the work environment and the possible impact of shading from adjacent buildings on the level of EML; and environment simulations with Integrative Lighting guidelines. Through gradual simulations, the aim is to verify the possibility of reestablishing minimum EML levels through compensatory electrical lighting configurations for a healthy photobiological day for individuals in this environment. The research foresees as a concrete object of study a working environment with prolonged stay during the day. In relation to simulations, the research will provide verification of the impact of shading on the quality of environments in terms of Lighting for a healthy photobiological day and proposing a methodology for compensating obstructed natural lighting. The research aims therefore to contribute to the current debates on sustainability and resilience in cities, regarding daylight and electric lighting solutions for healthier environments.

Lighting research has recently seen an increase in interest in the invisible effects of lighting on human performance, health, and well-being. In this paper, a systematic literature review was conducted to gather research evidence on the nonvisual effects of lighting on the elderly in terms of sleep, mood, and alertness. This study aims to investigate the lighting scenarios that have previously been tested on older adults and identify the most effective lighting scenarios that improve elderly sleep, mood, and alertness. The literature review included 24 studies with widely disparate results. Dynamic lighting scenarios and lighting interventions tailored to affect the circadian system (CS) seem to be the most effective in improving sleep and mood for older adults. On the other hand, the effect of lighting on the alertness of the elderly is still not fully understood due to a lack of relevant research. The review offers suggestions and recommendations for lighting scenarios for the elderly based on research-evidence-based criteria and strategies. It is recommended to intensify

In addition to stimulating the visual system, light incident on the retina stimulates other biological functions, also referred to as non-visual responses. Among the most notable biological functions are human circadian rhythms, which are bodily rhythms that, in constant darkness, oscillate with a period close to, but typically slightly longer than 24 hours. Twenty-four-hour light-dark patterns incident on the retina are the major synchroniser of circadian rhythms to the local time on Earth. Entrainment of circadian rhythms has been implicated in health and well-being. Light can also elicit an acute alerting effect on people, similar to a 'cup of coffee.' This review summarises the literature on how light affects entrainment and alertness and how it can be used to achieve these aims.

The magnitude of nocturnal melatonin suppression depends upon the spectrum, amount, and duration of light exposure. The functional relationship between melatonin suppression and the light spectrum and amount have been previously described. Only one duration-dependent parameter was needed to extend this functional relationship to predict nocturnal melatonin suppression during the early biological night from a variety of published studies. Those predictions suggest that ambient lighting commonly found in North American homes will not suppress melatonin for durations up to 3 h, whereas extended use of self-luminous displays in the home prior to sleep can.

Background: By affecting the internal timing mechanisms of the brain, light regulates human physiology and behavior, perhaps most notably the sleep-wake cycle. Humans spend over 90% of their waking hours indoors, yet light in the built environment is not designed to affect circadian rhythms. Objective: Using a device calibrated to measure light that is effective for the circadian system (circadianeffective light), collect personal light exposures in office workers and relate them to their sleep and mood. Setting: The research was conducted in 5 buildings managed by the US General Services Administration. Participants: This study recruited 109 participants (69 females), of whom 81 (54 females) participated in both winter and summer. Measurements: Self-reported measures of mood and sleep, and objective measures of circadian-effective light and activity rhythms were collected for 7 consecutive days. Results: Compared to office workers receiving low levels of circadian-effective light in the morning, receiving high levels in the morning is associated with reduced sleep onset latency (especially in winter), increased phasor magnitudes (a measure of circadian entrainment), and increased sleep quality. High levels of circadian-effective light during the entire day are also associated with increased phasor magnitudes, reduced depression, and increased sleep quality. Conclusions: The present study is the first to measure personal light exposures in office workers using a calibrated device that measures circadian-effective light and relate those light measures to mood, stress, and sleep. The study's results underscore the importance of daytime light exposures for sleep health.

The relevance of daylight went beyond issues of energy savings or illuminance required by standards, after the discovery of the third class of photoreceptors: intrinsically photosensitive ganglion cells (ipRGCs). These cells are responsible for non-visual responses, regulating the circadian rhythm, culminating, consequently, in the physiological and behavioral performance of individuals. This research aimed to analyze an example of the recurrent typology of office buildings in São Paulo, from the point of view of the performance of the users' circadian rhythm, with the objective of tracing design guidelines that aimed at taking advantage of natural lighting and well-being. being of its occupants. The method used the ALFA (Adaptive Lighting for Alertness) tool in the selected typology, in order to evaluate its potential in relation to the users' circadian rhythm. The results indicated the need to evaluate the pertinence of glass skin buildings for the city of São Paulo, whose window-to-wall ratio parameter exceeds that recommended by researchers in the area, as well as studies of facades based on the geometry of insolation, such as the analysis of the sky view factor and solar protection, in addition to the choice of selective glasses. So that users of office buildings can benefit from natural lighting, and the strategy becomes a viable resource, it is essential that architects design envelopes and internal spaces according to the reach of natural light, in quantities that favor the well-being, productivity and engagement of its occupants, and prevent the occurrence of glare.

The first evidence for a novel type of photoreceptor in humans was published in the form of an action spectrum for melatonin suppression. This action spectrum has very different spectral sensitivities compared to rod and cone photoreceptors. This discovery led scientists to rethink how lighting needs for human health are evaluated. Existing literature provides useful information about how to evaluate and report non-visual spectral sensitivities to light but lacks a unified description. In this paper, key concepts in the existing methods are identified and categorized to formulate a unified framework to assess the non-visual potential of light that is adaptable to a wide range of lighting solutions.

Background Alzheimer's disease (AD) patients exhibit aperiodic (random) patterns of rest and activity rather than the consolidated sleep/wake cycle found in normal, older people. This aperiodic pattern of behavior is very difficult for caregivers who must be vigilant to the needs of AD patients, because they are usually on a normal, 24-hour, circadian pattern of rest and activity. Clinical research has shown that exposure to very bright light in the day and darkness at night can consolidate rest and activity patterns in AD patients [1]. This clinical research was based upon more basic studies of circadian regulation by light exposure in animals and humans [2,3]. This large and growing body of research shows that bright light during the day is a powerful means of entraining natural circadian rhythms in all species, including humans. Depending upon the timing, duration, intensity and spectrum of the light, circadian rhythms can be synchronized or desynchronized (phase advanced or phase delayed) with the natural, 24-hour, daylight/darkness pattern. Very recent research has shown that the spectral sensitivity of the circadian system is very different than the spectral sensitivity of the retina used in visual activities such as reading and used to measure light in illuminating engineering. Very short wavelength (blue) light is maximally effective at affecting the circadian system [4,5,6] whereas middle wavelengths (yellow-green) are maximally effective for visual performance. Based on our knowledge of advanced lighting technologies and our understanding of neurophysiology and psychophysics of the human retina, we undertook a pilot study to determine if exposure to blue light from light emitting diodes (LEDs) could have a clinical impact on AD patients.

In addition to stimulating the visual system, light incident on the retina stimulates other biological functions, also referred to as non-visual responses. Among the most notable biological functions are human circadian rhythms, which are bodily rhythms that, in constant darkness, oscillate with a period close to, but typically slightly longer than 24 hours. Twenty-four-hour light-dark patterns incident on the retina are the major synchroniser of circadian rhythms to the local time on Earth. Entrainment of circadian rhythms has been implicated in health and well-being. Light can also elicit an acute alerting effect on people, similar to a 'cup of coffee.' This review summarises the literature on how light affects entrainment and alertness and how it can be used to achieve these aims.

The purpose of this research paper is to explore if there is a way to create a daylight environment, in spaces without access to it. This thesis hopes to benefit people living in spaces without access to daylight, and bring science and design a step closer to prevent Seasonal Depressive Disorder (SAD). Rather than curing SAD with a lamp, the focus will be on methods to uplift the mood and spirit of the human body and prevent the isolated feeling that can lead to depression. A thorough examination of studies done on the human circadian cycle is examined to understand the physical and physiologi- cal effects light has on the human body. After specifying the right dose of lighting required to achieve the positive daylight effects, the paper will look at qualities of artificial lighting and compare its dose to natural daylight. Different examples of lighting design in architecture will be used to analyse how designers have responded to the underexposure of daylight. Instead of giving al...

El presente artículo explora los diversos puntos de vista que han surgido sobre el uso seguro de dispositivos electrónicos, particularmente en el manejo de pantallas y los posibles efectos en la vista que puede conllevar su uso prolongado. Se determina que el buen uso de pantallas, y específicamente la luz azul de estas, no producen debilitamiento de la vista. Sin embargo, sí producen un empeoramiento de los síntomas que padecen pacientes con síndrome de resequedad ocular. Esto no quiere decir que la enfermedad agrave, sólo implica un aumento de irritación especialmente tras 3 horas continuas de exposición. Por otro lado, los estudios confirman perturbaciones del ciclo circadiano, patrones del sueño y cambios en concentraciones hormonales por uso prolongado de pantallas. El hecho de que las pantallas produzcan ceguera o enfermedades como la miopía parecen quedar como fake news.

The present article explores the distinct points of view that have had emerged upon the safe use of electronical devices, particularly about the management of screens and the possible effects on the sight that a prolonged use may lead to. It has been determined that the proper use of screens and specifically blue light of these, do not produce sight weakening. Nevertheless, they do worsen symptoms of the dry eye disease. This does not mean that the disease aggravates, it only implies an increase of irritation specially after 3 continuous hours of exposition. On the other hand, studies confirm perturbations on the circadian cycle, sleep patterns and changes on hormonal concentrations due to a prolongated usage time of screens. The fact that screens produce blindness or diseases like Myopia seem to remain as fake news.

Life on Earth evolved in day-and-night cycles. Plants and animals, including insects such as the fruit fly, have a biological clock that controls their circadian rhythms — as the 2017 winners of the Nobel Prize in Physiology or Medicine showed. Now, humans’ increasing reliance on artificial lighting is changing those rhythms.

This paper aims to combine theory and applied science;
academia and practice for the creative transformation of spaces
after dark taking into account a consistent environmental
awareness. It is based on the premise that design research in
the realm of architectural lighting design should function as
a development of practice, instead of being a distraction to
it. Architectural lighting design is a field within architecture
and spatial design that concerns itself primarily with the
illumination of architecture, including academic/institutional,
corporate, hospitality, monumental structures, residential, retail/
entertainment and site/facade projects after dark.

Does the iris colour of individuals have an impact on their preference of colour under white light emitting diodes (LEDs)?
To address this question, a study was conducted to examine how people with different iris colours respond to the colour and brightness of three scene settings under illumination from LEDs.

La recherche médicale et scientifique a démontré que notre santé et notre bien-être sont fortement liés la lumière.
Les impacts de la lumière sur la santé peuvent être regroupés en trois catégories :
– les influences de la lumière naturelle sur le fonctionnement biologique des êtres humains ;
– les impacts potentiellement négatifs de l’éclairage artificiel actuel sur la santé ;
– l’utilisation de la lumière à des fins thérapeutiques (luminothérapie).
La prise de conscience de notre sensibilité physique à la lumière (que la lumière soit « naturelle » ou « artificielle ») et la connaissance de ses bienfaits ou de ses méfaits potentiels visent à encourager son utilisation raisonnée.

Does the iris colour of individuals have an impact on their preference of colour under white light emitting diodes (LEDs)? To address this question, a study was conducted to examine how people with different iris colours respond to the colour and brightness of three scene settings under illumination from LEDs.

The urban fabric comprises the crossed and connected lines of streets, squares and landscaped areas. In the continued development of our urban spaces, academics and critics have often debated the dual role of urban design as a product and as a process as they watch over changes to cities through the times.

The paper examines using relatively recent discoveries on how evolution has embedded within all living organisms a natural sensitivity towards their native environment, in particular luminance levels and specific wavelengths of light. The studies conducted so far indicate that lighting installations that are visible after dark impact on humans, flora and fauna and influence our evolutionary dispositions, possibly with negative consequences. So far, little is known by the general public about the non-visual effects of light on human beings and the discovery of a new photoreceptor type in the eye (ipRGC -intrinsic photosensitive retinal ganglion cells) which is responsible for the regulation of the internal circadian clock, which, in turn, affects the immune system and triggers numerous biochemical processes.

Research about the impact of age on the perception of light quality by Dr. Karolina M. Zielinska -
Dabkowska and Veronika Labancová of the University of Applied Sciences, Technology, Business and Design Wismar/ Germany, has given unexpected results.