ArticleLiterature Review

Non-visual Effects of the Color Temperature of Fluorescent Lamps on Physiological Aspects in Humans

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Abstract

The non-visual effects of the color temperature of fluorescent lamps were reviewed based mainly on our recent studies with special reference to physiological aspects in humans such as arousal level, autonomic nerve system including heart rate variability, blood pressure and body temperature regulation, and sleep architecture. It was concluded that there obviously existed the non-visual effects of the spectral composition of fluorescent lamps on physiological aspects, as predicted based on the functions of the nuclei located on the photic non-visual pathway.

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... Light can cause cortisol levels in humans to rise or fall (Jung et al., 2010). Previous studies have investigated the relationship between cortisol secretion and the lighting environment (Küller and Wetterberg, 1993;Yasukouchi and Ishibashi, 2005;Sahin et al., 2014;Ivanova et al., 2016;Gentile et al., 2018;Choi et al., 2019;Rahman et al., 2019;Petrowski et al., 2021). However, there seem to be no consistent results from previous studies on the relationship between illumination and cortisol secretion. ...
... For instance, the experimental results from the work of Sahin et al. (2014), Gentile et al. (2018), and Choi et al. (2019) showed that the level of cortisol secretion does not seem to be affected by the CCT, illuminance, or lighting equipment. Conversely, Yasukouchi and Ishibashi (2005) and Petrowski et al. (2021) found that bright white light could evoke the highest cortisol secretion level when compared to red, blue, and dim white lighting environments. Regardless of the results of the above studies, it is known that the measurement of cortisol secretion levels has been widely used in lighting-related research. ...
Article
Previous research has indicated that lighting can affect people's concentration levels and working performance. However, it is unknown whether the same effect is also achieved when the lighting source is focused on the target to be identified. Thus, the objective of this study was to apply different lighting environments to evaluate the concentration level during a sustained attention task. To this end, 60 college students were recruited as participants (33 males and 27 females), and two lighting environments (focused and general lighting environments) with two sustained attention task times (15 and 30 min, respectively) were utilized. The task performance, electroencephalogram (EEG) signal, and cortisol secretion were employed to evaluate the concentration levels of the participants during the sustained attention task. The results show that the concentration level is affected by the lighting environment, and the participants performed better on task performance and cortisol secretion were activated in the focused lighting environment with the 15 min task time. However, there were no significant differences in task performance or cortisol secretion between the focused and general lighting environments with the 30 min task time. According to the EEG results, with either the 15 or 30 min task time, the ratio of theta to beta waves in the focused lighting environment was relatively stable, which indicates that the participants could concentrate more steadily when they worked in the focused lighting environment. In conclusion, the findings of this study could be applied to cognitive-related workplace lighting design and lighting-related research in the future. Relevance to industry This study's results on task performance, EEG, and cortisol secretion show that the participants in a focused lighting environment can concentrate more easily. These findings could serve as a reference for the lighting environment design of cognitive-related workplaces.
... The functions of food are divided into the primary function of "nutrition" and the secondary function of "preference" and deliciousness, as well as the "bioregulatory function" as a tertiary function [1]. Similarly, the functions of light include bioregulatory function [2][3][4][5][6][7][8][9][10][11] in addition to function as light for work at night or in indoor environments, function as signs, and function for the artistry and rendition of space. Among the bioregulatory function of light, the non-image forming effects of blue wavelength light through the intrinsically photosensitive retinal ganglion cells (ipRGC) [12,13] are attracting attention [8,[14][15][16][17]. ...
... Similarly, the functions of light include bioregulatory function [2][3][4][5][6][7][8][9][10][11] in addition to function as light for work at night or in indoor environments, function as signs, and function for the artistry and rendition of space. Among the bioregulatory function of light, the non-image forming effects of blue wavelength light through the intrinsically photosensitive retinal ganglion cells (ipRGC) [12,13] are attracting attention [8,[14][15][16][17]. The non-image forming effects of blue light include important biological regulations, such as increased vigilance [18,19], autonomic nervous arousal [20,21], and circadian clock adaptation to the environment [22][23][24][25], but that is why excessive exposure to blue light, especially before bedtime, could adversely affect sleep due to improper arousal and circadian rhythm disturbances [26][27][28][29][30]. ...
Article
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Background Although evidence of both beneficial and adverse biological effects of lighting has accumulated, biologically favorable lighting often does not match subjectively comfortable lighting. By controlling the correlated color temperature (CCT) of ambient lights, we investigated the feasibility of combined lighting that meets both biological requirements and subjective comfort. Methods Two types of combined lightings were compared; one consisted of a high-CCT (12000 K) light-emitting diode (LED) panel as the ambient light and a low-CCT (5000 K) LED stand light as the task light (high-low combined lighting), and the other consisted of a low-CCT (4500 K) LED panel as the ambient light and the same low-CCT (5000 K) stand light as the task light (low-low combined lighting) as control. Ten healthy subjects (5 young and 5 elderly) were exposed to the two types of lighting on separate days. Autonomic function by heart rate variability, psychomotor performances, and subjective comfort were compared. Results Both at sitting rest and during psychomotor workload, heart rate was higher and the parasympathetic index of heart rate variability was lower under the high-low combined lighting than the low-low combined lighting in both young and elderly subject groups. Increased psychomotor alertness in the elderly and improved sustainability of concentration work performance in both age groups were also observed under the high-low combined lighting. However, no significant difference was observed in the visual-analog-scale assessment of subjective comfort between the two types of lightings. Conclusions High-CCT ambient lighting, even when used in combination with low-CCT task lighting, could increase autonomic and psychomotor arousal levels without compromising subjective comfort. This finding suggests the feasibility of independent control of ambient and task lighting as a way to achieve both biological function regulation and subjective comfort.
... Given their relationship with various structures in the brain, such as the lateral geniculate nucleus (LGN), the suprachiasmatic nucleus (SCN), and the OPN, it is only reasonable to assume that the ipRGCs have an abundance of effects (such as melatonin secretion, alertness [18,80,81,110,111]), the most recently studied ones being on heart rate and heart rate variability. ...
Article
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Light is a fundamental aspect of our lives, being involved in the regulation of numerous processes in our body. While blue light has always existed in nature, with the ever-growing number of electronic devices that make use of short wavelength (blue) light, the human retina has seen increased exposure to it. Because it is at the high-energy end of the visible spectrum, many authors have investigated the theoretical harmful effects that it poses to the human retina and, more recently, the human body, given the discovery and characterization of the intrinsically photosensitive retinal ganglion cells. Many approaches have been explored, with the focus shifting throughout the years from examining classic ophthalmological parameters, such as visual acuity, and contrast sensitivity to more complex ones seen on electrophysiological assays and optical coherence tomographies. The current study aims to gather the most recent relevant data, reveal encountered pitfalls, and suggest future directions for studies regarding local and/or systemic effects of blue light retinal exposures.
... It is found that higher organisms are normally light-sensitive and the biological clock can be taken as a functional system. In 2002, Berson et al. [26] discovered the third type of photoreceptor cells in human body which can affect human biorhythm by controlling the secretion of melatonin. Yasukouchi and Ishibashi [27] found that there are two main neural pathways in the human brain when light signals are transmitted from the retina to the cerebral cortex. ...
Article
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Intelligent lighting has attracted lots of research interests to investigate all the possible schemes to support this need as human has spent more and more time indoor. Semiconductor-based illumination network is an ideal bearer to carry on this mission. In this paper, we propose the concept of Internet of Light (IoL) and define its key functionalities by introducing the information and communication technologies to the illumination networks. Our latest research progress on high-speed transmission, resource optimization, and light stroboscopic irradiation experiment based on loL platform show that loL can not only provide value-added services such as positioning and information transmission but also act like a sensor network as part of Internet of Things infrastructure. It confirms that with sensors for different purposes integrated into the lamp, loL helps people be aware of the environmental changes and make the adjustment accordingly, can provide cost-effective information service for Internet of Things applications, and supports the non-intrusive optical therapy in the future.
... In 2002, David Berson et al. of Brown University discovered the third type of photoreceptor cells in the retina, these nerve cells have different sensitivities to various light wavelengths and peak value is located at 490 nm, this is called citopic vision. Yasukouchi found that lighting color temperature has obvious physiological effects [27]. Studies show that the photobiological effect is sensitive to light of 490 nm wavelength and the corresponding maximum light efficiency is 3850 lm/W. ...
Article
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Compared with open roadways, traffic safety in highway tunnels requires more attention to build smoothly transitioned and well-coupled light environments for drivers to alleviate visual discomfort so as to achieve a balanced sense of driving safety and comfort. In this study, in order to overcome the drawbacks of existing tunnel lighting control modes that disregard the color temperature of natural light characteristics and collaborative influence of color temperature and luminance of natural light on tunnel lighting quality, one artificial neural network (ANN) model is designed and trained to simulate one physical lighting control system that takes into consideration color temperature and luminance simultaneously. In this model, multiple parameters of discrete and continuous types of input layer and output layer are synergistically analyzed. The model was also trained with quantities of field data from one tunnel in service and includes one hidden layer with 10 neurons. The simulation results showed that this model obtains a high degree of fitness with inside luminance and 100% recognition rate with inside color temperature in the threshold zone, which conforms to the regulation strategy of actual lighting control systems with high confidence. The proposed model will greatly enhance the reliability and sustainability of the lighting system during its normal operation, which can also support other lighting scenarios due to its flexibility and scalability with multiple-input and multiple-output (MIMO) capabilities.
... Other studies comparing sources of lighting based on their CCT (Correlated color temperature) show that exposure to sources with higher CCT (and thus more short-wavelength light) (Katsuura & Lee, 2019;Yasukouchi & Ishibashi, 2005) leads to an increase in arousal levels, autonomic nervous system activation (including heart rate variability, blood pressure, and body temperature regulation) and changes in sleep architecture. Wavelength comparisons by Hanifin et al. (Hanifin et al., 2019) have also indicated that circadian phaseshifting and enhancement of subjective and EEG correlates of alertness have a higher sensitivity to short-wavelength visible light. ...
Thesis
Background: Since the discovery of ipRGCs (intrinsic photosensitive retinal ganglion cells) in the retina, new research possibilities for studying the effects of light on the regulation of various behavioral and physiological functions that are independent of image formation arose. As ipRGCs are most sensitive to light of short wavelengths (460-480nm), this dissertation focuses on current topics related to the use of blue light, emphasizing its influence on circadi-an rhythms, sleep and cognitive performance and possible applications in clinical and non-clinical settings. Aims: The first study aimed to explore the effects of 20 minutes of narrow-bandwidth light exposure of different wavelengths on various neuropsychological and neurophysiological parameters of vigilance in healthy volunteers. The objective of the second study was to assess the effect of combining CBT-I (cognitive-behavioral therapy for insomnia) with wearing blue-light blocking glasses 90 minutes before bedtime on subjective and objective sleep pa-rameters and daily symptoms (anxiety, depression, hyperarousal). The third study aimed to examine subjective sleep quality in a population of healthy volunteers and its association with evening and night light exposure to screens of media devices. Methods: In the first study, twelve healthy volunteers went through 3 sessions of 20 minutes of light exposure of different wavelengths (455, 508, and 629 nm, with an irradiance of 14 μW/cm2), while EEG was recorded (including ERP (event-related potential) P300 and spec-tral characteristics) and behavioral data (subjective sleepiness, reaction time) gathered. In the second study, 30 patients completed a CBT-I group therapy program, with groups randomly assigned to either active (blue-light filtering glasses) condition, or placebo (glasses without filtering properties) condition. Patients were continually monitored by wristwatch actigraphy, kept their sleep diaries, and completed a standard questionnaire battery at admission and after the end of the program. Lastly, 693 participants in total completed an online questionnaire battery consisting of several sleep-related questionnaires: PSQI, FSS, MCTQ, MEQ and add-ed questions assessing the timing and character of the evening and night exposure to electron-ic devices (TV, PC, tablets and phones) and the use of various filters blocking short-wavelength light. Results: Our analyses showed that the short-wavelength light condition (455nm) in the first study, was found to be the most effective in terms of its alerting effect for the following vari-ables: subjective sleepiness, the latency of P300 response and absolute EEG power in higher beta (24-34 Hz) and gamma (35-50 Hz) range. The second study showed a greater reduction of anxiety symptoms in the active vs. placebo group of patients and significant prolongation of subjective total sleep time in the active group. When pre- and post-treatment results were compared in both groups separately, significant differences were observed for the scores in the depression and hyperarousal scales in the active group only. In the active group, there was also a significant reduction of subjective sleep latency and an increase of subjective total sleep time without a change in objective sleep duration, which was significantly shortened in the placebo group. In the third study, our analyses showed that longer cumulative exposure to screen light in the evening was associated with greater sleep inertia in the morning and longer sleep latency on workdays. Furthermore, exposure to screen light 1.5h before sleep or during night awakenings was also associated with a decreased chance to wake up before the alarm time, larger social jet-lag, more pronounce daytime dysfunction, decreased subjective sleep quality, and more fatigue. A statistical trend for an increase in the duration of sleep on week-days was also found in participants using blue-light filters in the evening hours. Conclusion: Our results provide valuable insight into the alerting effects of short-wavelength (blue) light. We also show that avoiding blue light in the evening may help reduce the phase-delaying effect of light and facilitate an improvement in sleep parameters and psychiatric symptoms. Altogether, these results may contribute to the development of new lighting or light-filtering systems and may also be applicable for healthy sleep promotion in both the general and clinical populations.
... High CCT light has greater effects than low CCT light on arousal level and melatonin suppression [16][17][18]. The physiological effects of high CCT of a fluorescent lamp were reported even before the discovery of ipRGCs [19][20][21][22]. In recent years, similar results have been obtained by exposure to LED lighting [23][24][25]. ...
Article
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Background Blue-enriched white light at night has the potential to delay the circadian rhythm in daily life. This study was conducted to determine whether the use of high correlated color temperature (CCT) light at home at night is associated with delay of sleep timing in university students. Methods The survey was conducted in 2014–2015 in 447 university students in Japan and 327 students in China. Habitual sleep timing and type of CCT light at home were investigated by using a self-administered questionnaire. The Japanese students were significantly later than the Chinese students in bedtime, wake time, and midpoint of sleep. They were asked whether the lighting in the room where they spend most of their time at night was closer to warm color (low CCT) or daylight color (high CCT). The amount of light exposure level during daily life was measured for at least 1 week by the use of a light sensor in 60 students in each country. Results The percentages of participants who used high CCT lighting at night were 61.6% for Japanese students and 80.8% for Chinese students. Bedtime and sleep onset time on school days and free days were significantly later in the high CCT group than in the low CCT group in Japan. The midpoint of sleep in the high CCT group was significantly later than that in the low CCT group on free days but not on school days. On the other hand, none of the sleep measurements on school days and free days were significantly different between the high CCT and low CCT groups in China. Illuminance level of light exposure during the night was significantly higher in Japanese than in Chinese, but that in the morning was significantly higher in China than in Japan. Conclusions The use of high CCT light at night is associated with delay of sleep timing in Japanese university students but not in Chinese university students. The effects of light at night on sleep timing and circadian rhythm may be complicated by other lifestyle factors depending on the country.
... LEDs in combination with smart lighting control can lead to an increase in light quality, an improved regulation of the circadian rhythm, and an increase in productivity (Hye Oh, Ji Yang, and Rag Do 2014;Karlicek 2012). Different light colour temperatures have been shown to influence human physiology (Yasukouchi and Ishibashi 2005), i.e. higher colour temperatures result in higher attention, and are therefore often used in work areas. Studies on human-centric lighting (HCL) have also reported that lighting adjusted to workers' needs contributes to the well-being of employees and prevents accidents at work (Pandharipande and Caicedo 2015). ...
Article
Lighting influences both private and working life. At the same time, it is a critical contributor to energy consumption. Despite the various technical solutions for making lighting “smart,” today’s lighting systems are often kept simple, and they are frequently not adjusted to user behaviors. This is especially the case for production and logistics facilities such as warehouses, where large areas have to be illuminated, and where lighting is often fully turned on while the warehouse operates. This paper presents a simulation model developed to evaluate the cost benefits potentially resulting from using smart lighting systems in warehouses. The simulation model allows for varying warehouse design and order picking process parameters, such as the length and number of aisles and cross aisles, or the number of order pickers in the warehouse. In addition, three different operating strategies for lighting systems representing different types of smart lighting technologies are implemented and compared to a conventional lighting system. A structured simulation study provides insights into how smart lighting systems interact with system design and process parameters, and how both collectively influence warehouse operating costs. The results of the simulation model and data obtained from a practical case indicate that smart lighting systems have great potential for reducing the energy consumption in warehouses relative to conventional lighting, and that, in addition to savings in cost, they can contribute to improving the environmental footprints of warehouses.
... Natural daylight is on the blue end of the range of color temperatures, while an incandescent lightbulb emits lower warmer light [55]. Therefore, a study setting with natural blue daylight, which is only present during the strongest sun irradiation hours [55,56], could affect cognitive-emotional neuromodulation independent of the applied stimulation [57,58]. We thus recommend that future studies control light conditions during rTMS experiments. ...
Article
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Growing evidence suggests that colored light exposure can affect several brain functions in addition to conscious visual perception. Blue as compared to green light has especially been shown to enhance alertness and vigilance, as well as cognitive functions. However, the role of light exposure in studies using non-invasive brain stimulation remains unclear. Here, we examined the impact of light on cognitive-emotional effects of prefrontal repetitive transcranial magnetic stimulation (rTMS). In a randomized within-subjects design, twenty participants (12 males, 26 ± 4 years) were exposed to blue or green light prior and concomitant to active or sham rTMS (1Hz, 15min, 110% of the resting motor threshold), applied over the right dorsolateral prefrontal cortex (DLPFC). In each condition, an emotional working memory task (EMOBACK) was presented pre- and post-intervention. Stimuli of the EMOBACK task were positive, negative and neutral words. Our results revealed valence-specific stimulation effects in dependence of colored light exposure. More specifically, task accuracy was significantly increased for positive stimuli under blue light and for negative stimuli under green light exposure. Our findings highlight the importance of state-dependency in studies using non-invasive brain stimulation and show blue light exposure to be a potential adjunctive technique to rTMS for enhancing cognitive-emotional modulation.
... These biological effects are traced back to the reaction to blue light due to a third photoreceptor in the human eye (Brainard et al. 2001;Brainard et al. 2015). Different colour temperatures, light intensities and light sources with various light spectra influence humans' circadian rhythm and physiological processes, such as pupil diameter and melatonin production (Schratz et al. 2013;Knez 2001;Yasukouchi and Ishibashi 2005;Lu et al. 2016). This affects performance and work efficiency, concentration, and the sleep-wake cycle. ...
Article
Full-text available
Artificial lighting is a constant companion in everyday private and working life, influencing visibility in interior spaces as well as outdoors. In recent years, new technical solutions have extended traditional lighting systems to become ‘smart’. Different types of smart lighting systems are available on the market today, and researchers have concentrated on analyzing their usability and efficiency, especially for private households, office buildings and public streets. This paper presents a systematic literature review to analyze the state-of-knowledge of technologies and applications for smart lighting systems. The results of the review show that smart lighting systems have been frequently discussed in the literature, but that their potentials in industrial environments, such as production and logistics, has rarely been addressed in the literature so far. Lighting systems for industrial environments often have very different requirements depending on the working environment and operating conditions. Based on the results of the literature review, this paper contributes to closing this research gap by discussing the usage potential of smart lighting systems to improve the efficiency of warehouse order picking, which is an application that may benefit from various functions smart lighting systems provide. Several propositions are developed that emphasize research opportunities and managerial implications in this context.
... On a psychological level, humans perceive a room as brighter and more pleasant with higher CCT levels of lighting (Boyce, 2004;Wei et al., 2014). Higher levels of CCT lighting in a room also subliminally influence human heart rate (Schlangen, 2010), autonomic nerve tone, hormonal secretion and motor function (Yasukouchi & Ishibashi, 2005). These actions occur from an increase in brain activity as a response to non-visual short wavelengths present in lighting with high CCT levels (Keis et al., 2014). ...
Article
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Numerous studies suggest a correlation between a school's physical environment and children's academic success. A variable within the classroom environment that has received little attention in the literature is the interior lighting. It is known that higher levels of correlated color temperature (CCT) lighting influence worker productivity in a workplace or laboratory setting. The CCT is the color of light emitted from a light source ranging from low (red) to high (blue). It is therefore necessary to uncover if a higher CCT level of lighting compared to the typically specified lower CCT level of lighting would influence student productivity and academic success in a classroom environment. This is a mixed method within-subjects case study designed to observe student behaviors as a way to gauge student productivity and academic success. Two different CCT levels of fluorescent lighting, which is the standard lighting fixture in most American public school classrooms, were installed in an existing second grade classroom using an ABAB study design. The study utilized both behavior mapping techniques to record student physical locations in the room and a time sampling non-participate observation technique to record on-task behaviors of the students for a duration of 5 months. The findings on the relation between the CCT of the lighting fixtures and student on-task behavior in an elementary classroom concluded that the higher CCT of the lighting the more student on-task behaviors were (p =.038) even while more male students physically moved around the classroom. This study has practical implications to facility managers and school officials interested in bettering classroom physical environments to advance student academic success.
... Exposure to pulsed light results in non-visual physiological responses in humans [1] [2] [3] [4] [5] [6] [7] [8] [9] . The present study aims to investigate whether such non-visual effects are influenced to a greater extent by the frequency of flickering or by the combination of colours of lighting, this research obeys to a previous experiment in which an intervention of Blue Pulsed LED was used as an addition to a task lamp in order to improve the state of alertness in humans when a continuous stream of pulses at 100 Hz was delivered to a conventional workspace [10] . ...
Article
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The aim of this study is to investigate the effect of a continuous stream of pulses of monochromatic blue pulsed (BP) and a combination of blue and green pulsed (BGP) light-emitting diode (LED) light conditions on physiological responses. This study is an approach to clarify the most suitable LED combination and flickering frequency to evoke alertness when a continuous stream of pulsed LED light is delivered and may suggest applications of continuous pulsed light as support for task illumination for shift workers, hospital nurses, school students or office employees. Combinations were delivered by exposures of BPLED and BGPLED pulses at 100, 200, and 400 Hertz over two background light colors (BLC). Participants were exposed to 12 different light conditions in a counterbalanced procedure. By integrating measures of electroencephalogram (EEG) and pupil constriction; results suggested significant changes in responses during the interaction of BLC, LED, and EEG. Beta waves exhibited a statistically significance (p < 0.05) in arousal levels when exposed to BG light, although no active task was involved during exposure. Furthermore, pupil reacted with larger constriction towards BGPLED exposure than towards monochromatic BPLED exposure, thus demonstrating that a continuous stream of pulses can deliver the same irradiance as if delivered in a continuous flow and without affecting perception as no flickering was perceived in any of the conditions by a qualitative evaluation.
... Licht ermöglicht im Allgemeinen das Sehen, beeinflusst das Verhalten und die Leistung des Menschen und beeinflusst den Schlaf-Wach-Rhythmus sowie die Stimmung und Motivation des Menschen (Boyce 2014). LEDs in Kombination mit einer intelligenten Lichtsteuerung können zu einer Erhöhung der Lichtqualität, einer verbesserten Regulation des Tagesrhythmus und einer Steigerung der Produktivität führen (Oh et al. 2014, Karlicek 2012 (Yasukouchi und Ishibashi 2005), sodass höhere Farbtemperaturen zu einer höheren Aufmerksamkeit führen und daher häufig in Arbeitsbereichen eingesetzt werden. Studien zum Human Centric Lighting (HCL) berichteten darüber hinaus, dass an die Bedürfnisse der Arbeitnehmer angepasste Beleuchtung zum Wohlbefinden der Arbeitnehmer und zur Vermeidung von Arbeitsunfällen beitragen (Pandharipande und Caicedo 2015). ...
Technical Report
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Die Zielsetzung des Projekts bestand in der Untersuchung von Nutzenpotenzialen intelligenter Beleuchtungssysteme in der Lagerhaltung. Intelligente Beleuchtungssysteme sind in der Lage, Gänge des Lagers nutzungsabhängig auszuleuchten, sodass die Beleuchtungsintensität und damit auch der Energieverbrauch an die tatsächliche Nutzung des Lagers angepasst werden kann. Da die Nutzungsintensität der Gänge des Lagers wiederum von der Steuerung des Lagers durch das Unternehmen abhängt und damit aktiv beeinflusst werden kann, entstehen zwischen den operativen Betriebsstrategien für das Lager und den Nutzenpotenzialen intelligenter Beleuchtungssysteme zahlreiche Wechselwirkungen. Diese Wechselwirkungen wurden im vorliegenden Projekt, insbesondere durch die Entwicklung integrierter athematischer Optimierungsmodelle für die Kommissionierung sowie durch die Entwicklung eines Simulationsmodells, explizit untersucht. Die Bearbeitung der Themenstellung ist in enger Zusammenarbeit mit dem projektbegleitenden Ausschuss erfolgt.
... The high color (colder/bluer) temperature of fluorescent light stimulates the non-visual pathway from the eye to various part of the brain that involves the circadian rhythm. [17] In our study the average time at which the lights were switched off in the room is 24 00 hrs. Assuming that lights were switched on at 1800 hrs the length of exposure to bright light would be around 5-6 hours. ...
Article
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Background: Exposure to light from viewing devices at night disturbs the circadian rhythm, especially sleep. The study aimed to assess (a) extent to which smart phones are used by medical undergraduate students during bedtime and to find their quality of sleep (b) the association of quality of sleep and cell phone variables. Methods: A cross sectional observational study was conducted among 450 medical undergraduate students. The participants completed Pittsburgh Sleep Quality Index (PSQI) questionnaire and a validated semi structured questionnaire consisting of demographic details and cell phone variables. Results: By dividing the subjects into three groups according to their usage (Group I <1 hour, Group II 1 to 2 hours, Group III >2 hours), Group III respondents had significant prolonged sleep latency, reduced sleep duration, sleep inefficiency and daytime sleep disturbances (P < 0.05). Lack of awareness about night shift mode, lying posture use while using phone during bedtime correlated with poor quality sleep (P < 0.05). Conclusions: Awareness about the negative impact of evening exposure to viewing devices on sleep and health should be emphasized.
... In classrooms, illumination is a very important design factor [4]. Illumination affects not only visual response but also nonvisual reactions, such as performance, mood, and attention [5][6][7][8]. Improvements in the quality of illumination environments increase productivity in students and teachers [9]. Different illumination environments in a classroom will trigger different sentiments, which may influence learners' ability to concentrate and attendance [10]. ...
Article
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This paper investigated foreign language learning efficiency in four different illumination environments (in different illuminance and color temperatures), focusing on the influence of the illumination environment on foreign language learners’ sentimental status, by means of foreign language skills testing in mind-map, objective evaluation of physiological reaction, and subjective evaluation of psychological reaction. It was shown that in different illumination environments, the language skills of foreign language learners were different, and their psychological and physiological reactions varied, which influenced the efficiency of foreign language learning. The results indicated that the ideal learning space was in high illuminance and low color temperature, which increased the stimulation in foreign language learners; promoted the formation of optimistic sentiment; and enhanced their interest in, and the quality and efficiency of, foreign language learning.
... Studies have shown that different light color temperatures influence the human physiology [24], such that lower color temperature is often used in living areas since it promotes relaxation [25]. Lighting could therefore be adapted to the natural biological daily rhythm of humans to mitigate negative effects resulting from artificial light. ...
Article
Light influences private and working life. Smart lighting systems make it possible to adjust the available light to the behavior and preferences of the user, which increases productivity and user well-being and contributes to lowering energy cost. The benefits of smart lighting systems have frequently been discussed for private households, office buildings and for public streets; their potential for supporting industrial processes has, in contrast, not attracted much attention so far. The work at hand gives an overview of smart lighting systems and the potential benefits associated with them. It then presents a few use cases to highlight how smart lighting could lower energy costs and improve operational processes in industrial companies.
... The results suggested that individuals under artificial skylights would have the same work performance as those under fluorescent lights with a lower phasic arousal level and same sleepiness. In other words, occupants under the fluorescent lights might have a slightly excessive tension of arousal level when achieving the same work compared with those under the artificial skylights [45]. ...
Article
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Background: Recently, more consideration is being given to the beneficial effects of lighting on the maintenance and promotion of the health and well-being of office occupants in built environments. A new lighting technology using Rayleigh scattering has made it possible to simulate a blue sky. However, to date, no studies have examined the possible beneficial effects of such artificial skylights. The aims of this study were to examine the non-visual effects of artificial skylights and conventional fluorescent lights in a simulated office environment and to clarify the feature effects of the artificial skylights. Methods: Participants were 10 healthy male adults. Non-visual effects were evaluated based on brain arousal levels (α-wave ratio and contingent negative variation [CNV]), autonomic nervous activity (heart rate variability [HRV]), work performance, and subjective responses during daytime exposure to either an artificial skylight or fluorescent lights, as well as nocturnal melatonin secretion. Results: Subjective evaluations of both room lighting-related "natural" and "attractive" items and the "connected to nature" item were significantly higher with the skylight than with the fluorescent lights. Cortical arousal levels obtained from the early component of the CNV amplitude were significantly lower with the skylight than with the fluorescent lights, whereas α-wave ratio and work performance were similar between the two light sources. The HRV evaluation showed that sympathetic nerve tone was lower and parasympathetic nerve tone was higher, both significantly, for the skylight than for the fluorescent lights during daytime. Nocturnal melatonin secretion was significantly greater before and during light exposure at night under the daytime skylight than under the fluorescent lights. Conclusions: Our results suggest that artificial skylights have some advantages over conventional fluorescent lights in maintaining ordinary work performance during daytime with less psychological and physiological stress. The findings also suggest that the artificial skylights would enable built environments to maintain long-term comfort and productivity.
... LEDs in combination with smart lighting control can lead to an increase in light quality, an improved regulation of the circadian rhythm, and an increase in productivity (Hye Oh, Ji Yang, and Rag Do 2014;Karlicek 2012). Different light colour temperatures have been shown to influence human physiology (Yasukouchi and Ishibashi 2005), i.e. higher colour temperatures result in higher attention, and are therefore often used in work areas. Studies on human-centric lighting (HCL) have also reported that lighting adjusted to workers' needs contributes to the well-being of employees and prevents accidents at work (Pandharipande and Caicedo 2015). ...
... These biological effects are traced back to the reaction to blue light due to a third photoreceptor in the human eye (Brainard et al. 2001;Brainard et al. 2015). Different colour temperatures, light intensities and light sources with various light spectra influence humans' circadian rhythm and physiological processes, such as pupil diameter and melatonin production (Schratz et al. 2013;Knez 2001;Yasukouchi and Ishibashi 2005;Lu et al. 2016). This affects performance and work efficiency, concentration, and the sleep-wake cycle. ...
Conference Paper
Lighting influences private and working life. At the same time, it is a critical contributor to energy consumption. Although there exist manifold technical solutions for lighting to become ‘smart’, today’s lighting systems are often kept simple, and they are frequently not adjusted to the user’s behavior. This paper presents the results of a systematic literature review on smart lighting systems and their related components. The results show that lighting systems for use in private households, office buildings and for public streets are well investigated in the literature. However, the potentials of smart lighting systems in industrial settings have only infrequently been discussed. The aim of this paper therefore is to present the state-of-knowledge on smart lighting systems and to highlight the potentials of such systems for production and logistics facilities.
... This study reported the ratios of the normal wave component of the EGG during sweet and salty taste stimulation to be significantly higher than those observed during bitter taste stimulation, with significant increases of this ratio under low color temperature exposure [30]. Yasukouchi and Ishibashi [31] reviewed the nonvisual effects of color temperature based mainly on their studies with special reference to sleep architecture, arousal level, and ANS (including parameters such as HRV, blood pressure, and body temperature regulation). ...
Article
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Here, we review the history and the trends in the research on the nonvisual effect of light in the field of physiological anthropology. Research on the nonvisual effect of light in the field of physiological anthropology was pioneered by Sato and colleagues in the early 1990s. These authors found that the color temperature of light affected physiological functions in humans. The groundbreaking event with regard to the study of nonvisual effects of light was the discovery of the intrinsically photosensitive retinal ganglion cells in the mammalian retina in the early 2000s. The interest of the physiological anthropology scientific community in the nonvisual effects of light has been increasing since then. A total of 61 papers on nonvisual effects of light were published in the Journal of Physiological Anthropology (including its predecessor journals) until October 2018, 14 papers (1.4/year) in the decade from 1992 to 2001, 45 papers (2.8/year) in the 16 years between 2002 and 2017, and two papers in 2018 (January–October). The number of papers on this topic has been increasing in recent years. We categorized all papers according to light conditions, such as color temperature of light, light intensity, and monochromatic light. Among the 61 papers, 11 papers were related to color temperature, 20 papers were related to light intensity, 18 papers were related to monochromatic light, and 12 papers were classified as others. We provide an overview of these papers and mention future research prospects.
... The iris pupil is opened and closed via a single constrictor or dilator muscle. The ANS is activated when we open our eyes, and the amount of light is adjusted by the iris [8]. Non-visual impacts of light are mediated by melanopsin-based photoreceptors in the retinal photosensitive ganglia cells [9]. ...
Article
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The existence of the retinohypothalamic pathway suggests that light may influence autonomic outflow activity. The objective of this study was to examine the correlation between the estimated iris muscle sympathetic‒parasympathetic area (IRIS) ratio and the sympathetic‒parasympathetic ratio (low frequency [LF]/high frequency [HF] ratio).
... The iris pupil is opened and closed via a single constrictor or dilator muscle. The ANS is activated when we open our eyes, and the amount of light is adjusted by the iris [8]. Non-visual impacts of light are mediated by melanopsin-based photoreceptors in the retinal photosensitive ganglia cells [9]. ...
Article
Full-text available
The existence of the retinohypothalamic pathway suggests that light may influence autonomic outflow activity. The objective of this study was to examine the correlation between the estimated iris muscle sympathetic-parasympathetic area (IRIS) ratio and the sympathetic‒parasympathetic ratio (Low Frequency (LF)/High Frequency (HF) ratio). The study population consisted of 200 females and 200 males (mean age, 32.4 ± 7.1 y). The IRIS ratio was determined from digital photographs of the iris in a computer setting. The LF/HF ratio was determined from records of heart rate variability obtained using a Holter implementation. The minimum LF/HF ratio was 1.4 and the maximum 5.6 (mean, 3.0 ± 0.8). The minimum IRIS ratio was 1.4 and the maximum 4.9 (mean, 2.7 ± 0.6). A strong positive correlation was determined between the LF/HF and IRIS ratios in the entire population (r=0.825; p<0.001) and positive correlations were also observed in males and females separately. The intraclass correlation between the LF/HF and IRIS ratios was 0.836. A strong correlation exists between the LF/HF and IRIS ratios.
... Respiration frequency may be controlled by the inputs from both chemoreceptors and baroreceptors and by the psychological factors. Furthermore, the biological effects of blue light could be mediated by non-image forming visual functions which involves intrinsically photosensitive retinal ganglion cells [1], [3], [4], [13], [14]. Blue light is also known to enhance alertness at least immediately after exposure [6]. ...
... Bright light may also disturb sleep, as can exposure to evening/night blue-spectrum light from monitors. 18 Nocturnal care interactions can average 42.6 per night. 12 We critiqued all published studies that investigated the use of conservative techniques to improve sound and light exposure and patient disruptions in the ICU and their impact on sleep and report our findings as a narrative review. ...
Article
Purpose: Sleep disturbance is common in intensive care units. It is associated with detrimental psychological impacts and has potential to worsen outcome. Irregular exposure to sound and light may disrupt circadian rhythm and cause frequent arousals from sleep. We sought to review the efficacy of environmental interventions to reduce sound and light exposure with the aim of improving patient sleep on adult intensive care units. Methods: We searched both PubMed (1966-30 May 2017) and Embase (1974-30 May 2017) for all relevant human (adult) studies and meta-analyses published in English using search terms ((intensive care OR critical care), AND (sleep OR sleep disorders), AND (light OR noise OR sound)). Bibliographies were explored. Articles were included if reporting change in patient sleep in response to an intervention to reduce disruptive intensive care unit sound /light exposure. Results: Fifteen studies were identified. Nine assessed mechanical interventions, four of which used polysomnography to assess sleep. Five studies looked at environmental measures to facilitate sleep and a further two (one already included as assessing a mechanical intervention) studied the use of sound to promote sleep. Most studies found a positive impact of the intervention on sleep. However, few studies used objective sleep assessments, sample sizes were small, methodologies sometimes imperfect and analysis limited. Data are substantially derived from specialist (neurosurgical, post-operative, cardiothoracic and cardiological) centres. Patients were often at the 'less sick' end of the spectrum in a variety of settings (open ward beds or side rooms). Conclusions: Simple measures to reduce intensive care unit patient sound/light exposure appear effective. However, larger and more inclusive high-quality studies are required in order to identify the measures most effective in different patient groups and any impacts on outcome.
... Known systemic physiological effects include the suppression of melatonin secretion, a hormone initiating sleep, by blue and white light [8][9][10][11][12][13][14] , and an interaction between cortisol, a hormone associated with stress, and white light exposure 15 . Blue and white light have also been effective in altering the core body temperature 16 and heart rate (HR) [16][17][18][19] , both of which fall in the late evening as part of the circadian rhythm. ...
Article
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Exposure to artificial coloured light is unavoidable in our modern life, but we are only just beginning to understand the impact of coloured light on human physiology. The aim of the present study was to determine effects of coloured light exposure on human systemic and brain physiology using systemic physiology augmented functional near-infrared spectroscopy (SPA-fNIRS). We measured changes in haemoglobin concentrations and tissue oxygen saturation in the left and right prefrontal cortices (L-PFC, R-PFC) by fNIRS, and also recorded skin conductance (SC), partial pressure of end-tidal CO2 (PETCO2), and heart-rate variability variables. 17 healthy adults (median age: 29 years, range: 25–65 years, 6 women) were exposed to blue, red, green, or yellow light for 10 minutes. Pre-light and post-light conditions were in darkness. In the L-PFC the yellow evoked a brain activation. SC and PETCO2 did not change during any of the coloured light exposures, but SC increased and PETCO2 decreased for all colours (except green) in the post-light period. Changes in L-PFC haemoglobin concentration were also observed during the post-light period but have to be interpreted with care, because heart rate and SC increased while PETCO2 decreased. The detected effects are potentially of high relevance for choosing room lighting and may possibly be applied therapeutically.
... Berson et al. from Brown University found that the third type of photoreceptor cells (ipRGC) of eye retina could transmit signal to the brain's biological clock regulatorthe suprachiasmatic nucleus (SCN), thus helping the human regulate circadian rhythms and other biological effects, including the change of human vital signs (blood pressure, pulse, blood oxygen, temperature, etc.), hormone secretion and the degree of alertness and excitement of the body [1]. YasuKouchi et al. studied that ipRGC accepted light signal and sent it to the brain's hypothalamus suprachiasmatic nucleus (SCN), which controls the pineal gland of the hypothalamus that secretes certain hormones, realizing the regulation of circadian rhythms and hormone control [2]. Hormones biologically regulated and affected by the light are mainly melatonin and cortisol. ...
Conference Paper
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Visual search tasks are mainly test methods of user performances for smartphone displays, which are usually used to assess the subjective quality of the visual display terminal. This study investigated the effect of different smartphone displays on visual search performance. A within-subject factorial design was used in this experiment. The visual search contents were Landolt Ring visual search performance, the search target of which was a ring with a gap in one of the four directions (up, down, right, left). The experiment was carried out in three smartphone displays. The search time and accuracy of each participant were recorded. The difference in search performance and subjective experiences among different smartphone displays was significant. Post hoc comparisons found that the search performance and the subjective experiences under the OLED was significantly better than the other smartphone displays, the low blue light LCD was second and he general LCD was the worst. These results revealed that visual search performance and the subjective experience were sensitive to different smartphones. The obtained results could be a reference to decide the visual search efficiency on different smartphone displays.
... In fact, the peak in the wavelength spectrum of the blue primary of our LED display is close to the peak sensitivity in the action spectrum of the Melanopsin-expressing ganglion cells (Brainard et al., 2001;Thapan, Arendt, & Skene, 2001). However, activation of these photoreceptors by shortwavelength light should result in an increase in alertness or arousal (e.g., Yasukouchi & Ishibashi, 2005), while our data show significantly lower arousal under short-wavelength blue light compared to longer-wavelength red light. In principle, this seemingly contradictory effect could be due to the modulating input of S-, M-, and L-cones (Kaiser & Boynton, 1996) to the Melanopsin-expressing ganglion cells (Dacey et al., 2005), where S-cone input is inhibitory, while L-and M-cone input is excitatory. ...
Article
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Previous studies on emotional effects of color often failed to control all the three perceptual dimensions of color: hue, saturation, and brightness. Here, we presented a three-dimensional space of chromatic colors by independently varying hue (blue, green, red), saturation (low, medium, high), and brightness (dark, medium, bright) in a factorial design. The 27 chromatic colors, plus 3 brightness-matched achromatic colors, were presented via an LED display. Participants (N = 62) viewed each color for 30 s and then rated their current emotional state (valence and arousal). Skin conductance and heart rate were measured continuously. The emotion ratings showed that saturated and bright colors were associated with higher arousal. The hue also had a significant effect on arousal, which increased from blue and green to red. The ratings of valence were the highest for saturated and bright colors, and also depended on the hue. Several interaction effects of the three color dimensions were observed for both arousal and valence. For instance, the valence ratings were higher for blue than for the remaining hues, but only for highly saturated colors. Saturated and bright colors caused significantly stronger skin conductance responses. Achromatic colors resulted in a short-term deceleration in the heart rate, while chromatic colors caused an acceleration. The results confirm that color stimuli have effects on the emotional state of the observer. These effects are not only determined by the hue of a color, as is often assumed, but by all the three color dimensions as well as their interactions.
... Recent research has confirmed that there are indeed have different preferences of color temperatures for different types of spaces [66]. In fact, it has been proven that the color temperature of lighting has an immense impact on the human physiological processes [67,68]. Generally, lower color temperatures are preferred for spaces such as bedrooms, hotels, and living rooms; higher color temperatures are normally required in work spaces such as offices, warehouses, and classrooms. ...
Article
The push for ubiquitous networking and device inter-connectivity in buildings is fueling the development of a new wave of smart devices with embedded electronics, sensors and wireless connectivity that can collect, process and exchange data. Commonly known as the Internet of Things (IoT), it encompasses, but is not limited to wireless sensor networks, home automation, mobile devices and lighting control systems. Smart lighting systems are of particular interest as they evolve from traditional lighting control by introducing autonomous control of light through feedback from integrated sensors, user data, cloud services and user input, bringing with it a host of benefits including increased energy savings, enhanced functionality, and user-centric lighting. In this paper, we review the current state of the art in smart lighting technology, focusing on energy-saving, commercial, and advanced smart lighting systems. Furthermore, we also present a review of smart lighting connectivity options and discuss potential advancements through the integration of visible light communication technology.
... Added to the behavioural effects, light has been shown to affect various psychophysiological aspects such as, alertness, arousal level, heart-rate, body temperature and circadian rhythm [41], [42]. Moreover, behavioural lighting research documents positive influences of light and colour on moods [43]. ...
Article
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The emergence of ubiquitous sensing and the Internet of things (IOT) have inspired the development of “smart” everyday objects, which offer tremendous opportunities for maintaining the quality of life in ambient assisted living (AAL) environments. Inspired by the future possibilities of connected everyday devices, we envision a peripheral activity based awareness system that captures human activity information and renders this information to enhance context awareness and support social connectedness between the elderly and their caregivers. Leveraging ambient intelligence and IOT technologies, ambient displays can convey activity information in the periphery of our attention. In particular, light has been used as a means to display ambient information and there is scientific evidence that it can enhance well-being, interconnectedness and improve productivity. In this work, we undertake two studies, first through an exploratory study we investigate the features of light suitable for conveying subtle activity information within the periphery of the users’ attention for promoting context awareness. Also, we examine the preferences, perceptions, and interpretations of ambient lighting configurations of prospective caregiver’s for conveying the activity information of older adults. In a second study, we assess the implications of activity awareness through lighting on cognitive performance, moods and social connectedness. The set-up and design decisions of the second study were partly informed by previous research and by the outcomes of the first experiment. Together, these studies provide additional design guidelines for representing activity information with ambient lighting and highlight potential benefits and usage possibilities for lighting displays within the AAL domain. Furthermore, the results indicate a significant effect of activity awareness on cognitive performance. However, there were no significant effects of activity awareness through lighting on moods and social connectedness. Finally, we discuss the design guidelines and implications of these findings for designing activity-based ambient lighting displays for AAL environments.
... Recent research has indicated that exposure to light results in non-visual physiological effects in humans [1][2][3][4][5][6][7][8][9], as well as visual effects (brightness or spectral distribution). Such research has resulted in the discovery of a third class of photoreceptors in the mammalian retina known as intrinsically photosensitive retinal ganglion cells (ipRGCs), which have a peak sensitivity to short-wavelength light of around 480 nm [10,11]. ...
Article
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Background Exposure to pulsed light results in non-visual physiological responses in humans. The present study aims to investigate whether such non-visual effects are influenced to a greater extent by the intensity of lighting or by the power (quantity) of lighting. Methods>Twelve healthy young male participants (23 ± 0.3 years, 21–24 age range) were recruited for the present study. Participants were exposed to light of varying levels of intensity and quantity whose frequency was held constant across the conditions, which consisted of exposure to blue (different intensity, constant quantity) and white (constant intensity, different quantity) LEDs. Pupillary constriction, electroencephalogram (EEG) alpha band ratio, subjective sleepiness, concentration and perception of blueness were measured. ResultsPupillary constriction and subjective concentration were significantly greater under the high-intensity and short pulse width (HS) condition than under the low-intensity and long pulse width (LL) conditions at three time points during exposure to high-intensity light. However, no significant differences were observed among the results at the three time points during exposure to different quantities of pulsed light. Conclusions The results of the present study indicate that non-visual influences of pulsed light on physiological function are mainly determined not by the quantity but by the intensity of the emitted light, with relatively higher levels of intensity producing more significant physiological changes, suggesting potent excitation of intrinsically photosensitive retinal ganglion cells.
... Based on the results of CCT values, the daylight CFLs have more natural color temperature than the other types of the studied lamps. Warm white light (CCT near 3000 0 k) facilitates relaxation and improves human's well-being and creates nice atmosphere, while daylight or cool white light (CCT near 5000 0 k) stimulates and activates the human body 23 . Therefore, warm white lamp can be employed for homes usage, while daylight lamp can be used for offices rooms. ...
Article
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Background: Some characteristics of lighting sources such as color properties and ultraviolet emissions have important roles on visual and non-visual health effects of lighting. This study aimed to investigate the light emissions of some compact fluorescent lamps (CFLs) and incandescent lamps commercially available to the Iranian consumers. Methods: Sixty lamps included 48 single envelope CFLs, and 12 incandescent lamps available in the electrical devices markets (in the west of Iran) were randomly selected from famous manufacturers between 2014 and 2015. Lighting characteristics and ultraviolet (UV) emissions were measured using spectroradiometer and calibrated radiometer, respectively. Data analysis was performed using SPSS16 software. Results: Color-rendering indexes of the studied lamps were above 80, which showed good color properties. The daylight CFLs had more desirable and natural color temperature (near to 5000 0k) compared with the other types of the studied lamps. Occupational exposures for periods up 8 h to UVB from the studied lamps at distances up to 0.25 m were more than the recommended limits. Moreover, public exposures for periods up 16 h to UVB from the studied lamps at any distances up to 2 m were more than the recommended limits. Conclusions: Warm white lamps are suitable for homes usage, while daylight lamps can be used for offices rooms. Occupational exposure to single envelope CFLs near the body at distances of less than 25 cm can result in overexposure to actinic UV. Moreover, CFLs must be used at distances greater than 200 cm for public exposure.
... In humans, light is a crucial source of stimuli that enhance the arousal systems and entrain their rhythms to those of the external environments. These actions of light can be elicited independently of the functions of image-forming vision and have greater sensitivity to blue wavelength light [1][2][3][4]. This is presumably resulted from the involvement of intrinsically photosensitive retinal ganglion cells (ipRGCs) expressing the photopigment melanopsin, and which are sensitive to blue wavelength around 480 nm [5][6][7][8][9]. ...
Article
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Background: Blue light containing rich melanopsin-stimulating (melanopic) component has been reported to enhance arousal level, but it is unclear whether the determinant of the effects is the absolute or relative content of melanopic component. We compared the autonomic and psychomotor arousal effects of melanopic-enriched blue light of organic light-emitting diode (OLED) with those of OLED lights with lesser absolute amount of melanopic component (green light) and with greater absolute but lesser relative content (white light). Methods: Using a ceiling light consisting of 120 panels (55 × 55 mm square) of OLED modules with adjustable color and brightness, we examined the effects of blue, green, and white lights (melanopic photon flux densities, 0.23, 0.14, and 0.38 μmol/m(2)/s and its relative content ratios, 72, 17, and 14%, respectively) on heart rate variability (HRV) during exposures and on the performance of psychomotor vigilance test (PVT) after exposures in ten healthy subjects with normal color vision. For each of the three colors, five consecutive 10-min sessions of light exposures were performed in the supine position, interleaved by four 10-min intervals during which 5-min PVT was performed under usual fluorescent light in sitting position. Low-frequency (LF, 0.04-0.15 Hz) and high-frequency (HF, 0.15-0.40 Hz) power and LF-to-HF ratio (LF/HF) of HRV during light exposures and reaction time (RT) and minor lapse (RT >500 ms) of PVT were analyzed. Results: Heart rate was higher and the HF power reflecting autonomic resting was lower during exposures to the blue light than the green and white lights, while LF/HF did not differ significantly. Also, the number of minor lapse and the variation of reaction time reflecting decreased vigilance were lower after exposures to the blue light than the green light. Conclusions: The effects of blue OLED light for maintaining autonomic and psychomotor arousal levels depend on both absolute and relative contents of melanopic component in the light.
Article
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Light simultaneously induces visual and non-visual effects. Although the differences in the spectral sensitivity of intrinsic photosensitive retinal ganglion cells induce opposing influences on physiological responses, it is difficult to independently measure only non-visual effects. Therefore, the reported effects of light color on physiological responses are inconsistent. This study aimed to clarify the visual and non-visual effects of light color on physiological responses. Three different conditions were employed to construct a lighting environment in which light colors were difficult to perceive due to chromatic adaptation and change blindness: constant white light (baseline condition), a gradual transition from white to blue light, and a gradual transition from white to red light. The physiological responses (brain activity, heart rate variability, and electrodermal activity) of 21 participants were measured with and without light color perception. The results suggested that blue light causes more non-visual effects compared to red light as blue light induces brain activation in some regions of the PFC (p < 0.05) and increases sweating, although the differences were not statistically significant. A mean comparison suggested that the visual effects of blue light showed tendencies toward a calming role for the prefrontal cortex and inhibition of sweating, but the differences were not statistically significant. Another mean comparison suggested that the visual effects of red light tended to enhance sweating, but the differences were not statistically significant. Visual and non-visual effects did not cause significant differences in heart rate variability. Additionally, a mean comparison did not reveal any significant tendencies.
Article
In the context of epidemic normalization, it is particularly important to explore environmental health from the perspective of adaptation of patient pathological characteristics to achieve sustainable goals. Although recent studies have confirmed the effects of ventilation and sound on human health and revealed that improvement in the quality of patient recovery can be achieved by controlling the material exchange between people and the environment, it remains unclear in terms of the mutual drivers of intangible material (ventilation and sound) and patient recovery quality. This study establishes a link between the physical environment and the quality of rehabilitation by reporting on the ventilation and noise levels at a rehabilitation facility for people with cognitive disorders. Second, a successful design optimization technique based on the adaption of pathological traits is suggested. The Centre fails to fulfil the ventilation and acoustic criteria for indoor comfort, according to the findings of the real testing. The study procedure demonstrates that (1) enhancing the space's openness to unblock the airflow can only have its effect maximised if the layout is taken into account to accommodate the wind direction.; (2) the spatial scale is not the only factor affecting the sound quality of the environment; and (3) increasing the openness of the area can improve the quality of sound transmission and reduce noise in the area, but at the same time, it will have some impact on other areas.
Article
Adverse weather such as fog will reduce drivers' visual recognition ability, and important visual information in the driving will be weakened and even lost, which brings risks to driving safety. This paper sets out to explore causes for the decline in driving visual ability in foggy sections at night based on drivers' visual recognition demand mechanism. The purpose is to study the influence of light source characteristics on visual distance under open traffic conditions. Through an outdoor visual recognition test, data were collected on the visual recognition distances of 12 car drivers to standard gray small targets, under different light source characteristics and meteorological visibility conditions. Results revealed that the latter conditions, along with illuminance and correlated color temperature affected drivers' visual recognition ability in low meteorological visibility sections at night. At the same illuminance and meteorological visibility, a light source with high correlated color temperature could improve visual distance. The multivariate power function model of meteorological visibility, illuminance at the target and driver's visual distance in foggy areas were obtained by fitting. The research methods and conclusions could provide technical reference for improving traffic visual distance at night, and thus help lay a foundation for road construction and traffic control technology in foggy areas.
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The luminous environment had a significant influence on the working efficiency, especially for the learning efficiency of undergraduates. Correlated color temperature (CCT), as an important evaluation parameter of luminous environment, affects the learning efficiency and fatigue obviously, so it is important to select the suitable CCT for classrooms. To explore the comprehensive influence of CCT on undergraduates and thereby, find the suitable CCT in different environments for classrooms, a classroom model was built with 6 CCTs (3000K, 3700K, 4400K, 5100K, 5800K, and 6500K) under three air temperatures of 23 °C, 26 °C and 29 °C. The questionnaire survey was conducted to analyze the subjective feeling including thermal sensation, thermal comfort and CCT satisfaction for 32 undergraduates, while the experiment was done to measure the attention and relaxation of undergraduates under the different luminous environment. The questionnaire results showed that the thermal sensation vote reduced by 1.65–2.75 when CCT increased from 3000K to 6500K, and the same thermal sensation of slightly warm (TSV = 1) was achieved when CCTs were 3000K, 4400K and 5800K at 23 °C, 26 °C and 29 °C, respectively. These indicated that CCT could obviously regulate the subjective thermal perception at different air temperatures. The fitting analysis of subjective perception and physiological parameters showed that the average attention and relaxation were the highest when the thermal sensation was slightly cool (TSV = −0.40) and slightly warm (TSV = 0.59), respectively. And moderate thermal comfort (TCV = 0.03) maximized the average attention, and increased thermal comfort increased the relaxation. The suggested CCTs for learning were 4400K–5100K, 5100K–5800K, and 5800K–6500K of 23 °C, 26 °C and 29 °C, respectively. And the suggested CCTs for rest were 3700K–4400K, 4400K–5100K, and 5800K–6500K of 23 °C, 26 °C and 29 °C, respectively. This provides a comfortable and efficient lighting environment for undergraduates.
Chapter
Waste electrical and electronic equipment (WEEE), often entitled e-waste is very significant group of waste these days, due to the enormous use of computers and mobile devices by our society. This chapter shows the possibility of the mechanochemical treatment of waste cathode ray tubes, printed circuit boards, displays (PDP or LCD), batteries and fluorescent lamps. The most common way of recycling this type of waste is the recovery of valuable metals (including rare Earth ones mainly from fluorescent lamps). In the case of batteries, the electrochemical characterization and tests of potential reuse is often discussed.
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In this article, we present a design method for multifunctional illumination sensors, which can simultaneously detect blue light hazard, circadian rhythm, as well as scotopic and photopic vision based on spectral analysis. We showed that illumination sensors for blue light hazard, circadian rhythm, scotopic vision, and photopic vision can be fabricated based on attaching the Si photodiode S5981 to the bandpass filters DTB435, DTB470, DTB500, and DTB545 with a thickness of 4 mm. The deviations of the central wavelengths of their response curves from those of the four response functions of the human eye are 3, 11, –3, and –8 nm; the corresponding deviations of the full widths at half maximum are 16, 5, 1, and –7 nm, and the corresponding relative deviations of the integrals over the visible wavelength range of 380–780 nm are 32.0%, 15.2%, 4.5%, and 1.9%. The average absolute and relative errors of the values measured with our self-made photopic vision illumination sensor in ten independent measurements are 7.82 lx and 1.77%, respectively. Six kinds of light sources were measured with the circadian rhythm illumination sensor, and all relative errors are less than 5%, and the average value is 2.63%. The experimental results showed that this design method is feasible, and the research can provide a reference for enriching optical bioluminescence sensors.
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With the recent advances in photobiology research and light-emitting diode technology, considering the circadian effects and the potential health benefits of lighting has attracted much attention. In this work, to achieve a white light-emitting LED cluster with beneficial and tunable circadian effects, a red-green-blue-warm white colour-mixing method based on pulse width modulation has been introduced and developed. Five optimal spectral power distributions were achieved with the correlated colour temperatures of 2700, 4000, 5000, 6500 and 8000 K that provide maximum colour-rendering indices of 95.0, 96.6, 96.8, 95.6 and 93.5 for each correlated colour temperature. Moreover, the Bellia model was modified to take into account the reduction in spectral transmittance of the human eye that occurs with age. Using the five spectral power distributions, based on the eye spectral transmittance with age-related change, we studied the change of the circadian effect with corneal illuminance at the different correlated colour temperatures. Solutions are provided for scenarios where circadian effect should be avoided for different age groups while the reasonable illuminance and colour temperature are maintained.
Article
Under the pressure of ensuring student visual performance, this study investigated whether improving the classroom lighting is helpful in relieving the daytime serum melatonin concentration in undergraduates who suffer from sub-syndromal seasonal affective disorder in winter. Two negative control groups (Undergraduates without sub-SAD, lighting conditions 300 lx, 4000K), two positive control groups (undergraduates with sub-seasonal affective disorder, lighting conditions 300 lx, 4000K) and six positive intervention groups (undergraduates with sub-seasonal affective disorder, lighting conditions 1000, 2000, 3000 lx and 4000K and 5000K). There were eight participants in each group (four males and four females). A total of 80 participants took part in 15 successive days of study, and the melatonin was measured every seven days. After comparing participants’ melatonin levels before and after exposure, statistical analysis revealed: (1) Participants with sub-seasonal affective disorder had a higher daytime serum melatonin level than the normal; (2) Increasing the illuminant colour temperature or illuminance in daytime can effectively restrain sub-seasonal affective disorder participants’ daytime serum melatonin secretion; (3) Compared to the 4000K intervention, the 5000K light source affected the participants’ daytime serum melatonin suppression more significantly. These results provide suggestions for classroom lighting in sunless areas from the aspect of melatonin rhythm.
Article
A white light emitting diode (WLED) based on ZnO nanorods (ZNRs)/polymer blend p-n heterojunction has been fabricated. Different from the common commercial GaN WLEDs with a blue emission, the ZNRs/polymer blend WLED exhibits a blue-green emission peaked at 490 nm. Thus, the ZNRs/polymer blend WLED has a better cirtopic effect and smaller blue-light hazard. To get the 490 nm emission, intrinsic n-type ZNRs were annealed in a mixed gas of He and Zn vapor, and poly (9, 9-dioctylfluorene) (PFO) was mixed into the p-type polymer blend. Poly (3-hexylthiophene) (P3HT) was also mixed into the blends to get red emission. Results show the ZNRs/polymer blend heterojunction exhibits high-quality white-light emission with superior chromaticity coordinate (0.30, 0.33) as well as good cirtopic-effect spectrum. In comparison with the commercial GaN WLED, the ZNRs/polymer blend WLED is significantly potential for human health and work efficiency.
Conference Paper
Based on the analysis of visual cognition demands mechanism and behavioral characteristics of safety driving, this paper presents a study on light source characteristics of visual cognition distance which increased by artificial lighting in nighttime highway foggy section. This experiment aims to improve the driving safety and efficiency. Experiment scene simulates nighttime highway foggy section. We conduct the experiment of visual cognition in target by drivers under the different light source characteristics and visibility. A random sample of 12 drivers was selected for this experiment. Binary linear model was used to fitting the experimental data, the relationship between visibility and visual cognition distance under different illumination levels, and color temperature was established after analyzing the experimental data. Results demonstrate that higher color temperature light can increase driving visual distance under the same visibility and illumination, improving luminance can meet the demand of driving visual distance. The research method and conclusion in this paper can provide technical reference for the light source setting of the highway foggy section in nighttime and lay the foundation for the future study of safety guarantee technology highway foggy section at nighttime.
Article
Background: The therapeutic effects of visible light and infrared is especially often used in physiotherapy. Objective: The purpose of this study was to determine the effect of exposure to radiation on the motor units activity. Methods: The study included 29 volunteers whom was evaluated the spontaneous and voluntary bioelectric activity of the trapezius muscle using surface electromyography (value of average amplitude and frequency), before and immediately after a 15-minute irradiation. Additionally was assessed the range of motion of the cervical spine and trigger points pain sensitivity to the pressure. Results: No statistically significant changes in the pain sensitivity threshold and the range of motion after the irradiation applied. On the other hand, a 15-minute exposure to radiation induced an increase in the value of average amplitude of rest-related as well as exercise-related potentials and an increase in the average value of frequency of the right side biopotentials at rest and of both sides for active elevation. Conclusions: Infrared radiation and visible red light have a stimulating effect on the muscle ability to develop active contraction. It is proposed that the changes being observed are associated with the thermal effect of radiation as well as with the so-called extra-visual effects.
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The circadian rhythm in melatonin production in mammals is regulated by a suprachiasmatic (SCN) leads to spinal cord leads to pineal circuit. In the present investigation the possible participation of the paraventricular nucleus of the hypothalamus (PVN) in the SCN leads to spinal cord segment of this circuit was investigated in the rat. Bilateral lesions of the PVN area were produced and one to two weeks later melatonin production was evaluated by measuring the activities of the two pineal enzymes required for the formation of melatonin from serotonin, indoleamine N-acetyltransferase (NAT) and hydroxyindole-O-methyltransferase (HIOMT), and urinary 6-hydroxymelatonin, the major melatonin metabolite. In some cases pineal melatonin was also measured. Control animals received sham-PVN lesions. Histological examination of the lesions indicated that the PVN were bilaterally destroyed 100% in 12 animals. The nighttime pineal melatonin and urinary 6-hydroxymelatonin values in this group were reduced about 90%, nighttime pineal NAT activity was reduced about 98%, and HIOMT activity about 75%. The urinary 6-hydroxymelatonin values of PVN-lesioned animals and animals with denervated pineal glands were similar. In animals with hypothalamic lesions involving less than 30% of the PVN, nighttime values of NAT, HIOMT, and urinary 6-hydroxymelatonin were normal; in animals with 30 to 95% PVN damage these parameters were altered to a small degree. These studies, together with histochemical observations, indicate the SCN neurons responsible for pineal circadian rhythms project to the PVN area of the hypothalamus.
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To be adaptively useful, internal circadian clocks must be entrained (synchronized) to daily rhythms in the external world. The entraining process adjusts the period of the internal clock to 24 hours and its phase to a value that determines the organism's temporal niche (e.g., diurnal and nocturnal). For most vertebrates, the dominant environmental synchronizer is light. All vertebrates employ specialized photoreceptor cells to perceive synchronizing light signals, but mammals and nonmammalian vertebrates do this differently. Mammals concentrate circadian photoreceptors in the retina, employing rods, cones, and a subset of retinal ganglion cells that are directly photosensitive and contain an unusual photopigment (melanopsin). Nonmammalian vertebrates use photoreceptors located deep in the brain and in the pineal gland as well as others in the retina. Such photoreceptor extravagance is difficult to explain. It seems likely that the different photoreceptor classes in this elaborate sensory system may have specialized roles in entrainment. There is some evidence that this is in fact the case. Furthermore, this nonvisual "circadian" photoreceptive system also controls acute behavioral responses to light (masking), pupillary constriction, and photoperiodic regulation of reproductive state. We review some of the early work on birds and describe new findings that indicate specific roles for retinal rods, cones, and photosensitive retinal ganglion cells in mammals.
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A study on the effects of different color temperatures of fluorescent lamps on skin and rectal temperatures in a moderately cold environment involving (i) changes in skin temperature of 7 male subjects exposed to an ambient temperature ranging from 28 degrees C to 18 degrees C (experiment I) and (ii) changes in skin and rectal temperatures and metabolic heat production of 11 male subjects exposed to ambient temperature of 15 degrees C for 90 min (Experiment II) was conducted. In Experiment I, the reduction of mean skin temperature from the control value was significantly greater under 3000 K than under 5000 K or 7500 K lighting. In Experiment II, the reductions in mean skin temperature and rectal temperature were respectively greater and smaller under 3000 K than those under 5000 K or 7500 K lighting. However, metabolic heat production was not affected by color temperature conditions. The relationships between morphological and physiological parameters revealed that no significant relation of rectal temperature to body surface area per unit body weight was found only under 3000 K. Furthermore, while the mean skin temperature was independent on the mean skinfold thickness under 3000 K, a significant negative correlation between the rectal and mean skin temperatures was observed. Therefore, body heat loss might be suppressed effectively by increasing the vasoconstrictor tone under a color temperature of 3000 K, and the body shell was dependent only on morphological factors under 5000 K and 7500 K lighting.
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The brains of nonmammalian vertebrates contain populations of photoreceptive cells that are important for establishing the circadian rhythms of physiology and behavior. Do mammals, which evolved from strictly nocturnal ancestors, contain such photoreceptive cells? As Menaker explains in his Perspective, new work (including Lucas et al. and Van Gelder et al.) establishes that the mammalian retina contains photoreceptive ganglion cells carrying the photopigment melanopsin, which contribute to the entrainment of circadian rhythms to the light-dark cycle.
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A novel photoreceptor of the mammalian retina has recently been discovered and characterized. The novel cells differ radically from the classical rod and cone photoreceptors. They use a unique photopigment, most probably melanopsin. They have lower sensitivity and spatiotemporal resolution than rods or cones and they seem specialized to encode ambient light intensity. Most surprisingly, they are ganglion cells and, thus, communicate directly with the brain. These intrinsically photosensitive retinal ganglion cells (ipRGCs) help to synchronize circadian rhythms with the solar day. They also contribute to the pupillary light reflex and other behavioral and physiological responses to environmental illumination.
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