The effects of artificial light at night on spider brains.

Artificial light at night (ALAN) is an increasingly pervasive pollutant that alters animal behaviour and physiology, with cascading impacts on development and survival. Recent evidence links exposure to ALAN with neural damage, potentially due to its action on melatonin synthesis, a powerful antioxidant. However, these data are scarce and taxonomically limited. Here, we used micro-CT to test the effects of short-term ALAN exposure on brain volumes in the Australian garden orb-weaving spider (Hortophora biapicata), a species commonly found in urban areas and, specifically, around street lights. We found that short-term ALAN exposure was linked to reductions in the volumes of brain structures in the primary eye visual pathway, potentially as a consequence of oxidative stress or plastic shifts in neural investment. Although the effects of ALAN were subtle, they provided new insights into potential mechanisms underpinning the behavioural and physiological impacts of ALAN in this important urban predator.

The effects of light emitting diodes on mitochondrial function and cellular viability of M-1 cell and mouse CD1 brain cortex neurons.

The invention of Light Emitting Diode (LED) revolutionized energy-efficient illumination, but concerns persist regarding the potential harm of blue light to our eyes. In this study, we scrutinized the impact of LED light characteristics on eyes using two cell types: M-1 (rich in mitochondria) and CD-1 (neuronal). Variations in color rendering index (CRI) and correlated color temperature (CCT) were investigated, alongside exposure durations ranging from 0 to 24 hours. The findings illuminated the potential benefits of high-quality LED lighting, characterized by a high CRI and low CCT, which emits a greater proportion of red light. This form of lighting was associated with enhanced cell proliferation, elevated ATP levels, and reduced oxidative stress. In contrast, LEDs with low CRI and high CCT exhibited adverse effects, diminishing cell viability and increasing oxidative stress. These results suggest that high-quality LED lighting may have neuroprotective potential as a treatment option, such as for retinal ganglion cells.

Circadian lighting effect for inpatients with schizophrenia: A prospective cohort study.

OBJECTIVES: In schizophrenia, nonspecific lighting likely causes sleep timing disturbances, leading to distress and poorer clinical status. However, the effect of exposure to circadian lighting on psychopathology outcome in schizophrenia remains unknown. Hence, this study aimed to develop such an intervention and investigate its impact on schizophrenia. METHODS: Twenty schizophrenia patients at a psychiatric nursing institute were monitored over 10 weeks, with assessments using the Brief Psychiatric Rating Scale (BPRS) and Mini-Mental State Examination (MMSE) conducted at baseline, weeks 3 (T1), 7 (T2), and 10 (T3). RESULTS: Circadian lighting significantly improved BPRS scores between T1-T2 (p < .05) and T1-T3 (p < .001), with affectivity scores also showing significant enhancements postintervention. Notably, female participants exhibited substantial improvements in BPRS scores from T1 to T3 (p < .01), while male participants demonstrated significant gains in MMSE scores from T1 to T2 (p < .01). CONCLUSIONS: Circadian lighting presents a promising intervention for improving psychiatric outcomes in schizophrenia, with distinct benefits observed across different psychopathological aspects and genders. These findings underscore the potential of lighting chronotherapy in psychiatric clinical practice and warrant further exploration in related research.

Effect of Ambient Lighting on Intraocular Pressure Rhythms in Rats.

Purpose: The purpose of this study was to determine the effects of ambient lighting on intraocular pressure (IOP) rhythmicity and variability. Methods: IOP was continuously recorded by wireless telemetry from rats under light/dark (LD), dark/light (DL), asymmetric (6L18D and 18D6L), constant dark (DD), and constant light (LL) cycles. In some DD experiments, 1-hour light pulses were presented at varying times. IOP rhythmicity and variability were respectively quantified via cosinor analysis and peak detection algorithms that identified transient and sustained fluctuations. Results: Rat IOP peaked at night and troughed during the day with LD amplitude of 8.7 ± 3.4 mm Hg. Rhythmicity persisted in DD and LL with a free-running period of 24.1 ± 0.3 and 25.2 ± 0.4 hours, respectively. Peak-to-trough amplitude was approximately 60% smaller in LL, often disappeared after 1 to 2 weeks as daytime IOP drifted 2.6 ± 1.5 mm Hg higher, and returned to approximately 60% larger in LD. Rhythmicity was similarly impacted but resynchronized to DL over 4 to 6 days. Rhythmicity was unaltered by short photoperiods (6L18D), but the nocturnal IOP elevation was markedly shortened by long photoperiods (18L6D) and temporarily lowered to daytime levels by light pulses during the subjective night. Transient and sustained event rate, amplitude, interval, and energy content were nearly identical in LD, DD, and LL. Conclusions: Aqueous humor dynamics of rat eyes are intrinsically configured to set IOP at daytime levels. Circadian clock input modulates these dynamics to elevate IOP at night. Light at night blocks this input, sending IOP back to daytime levels. Effects of abnormal lighting on IOP rhythmicity may contribute to pressure-related ocular neuropathies.

Artificial light at night alters the locomotor behavior of the Mediterranean sea urchin Paracentrotus lividus.

Artificial light at night (ALAN) is a recognized source of anthropogenic disturbance, although its effects on biological systems have not been fully explored. Within marine ecosystems, coastal areas are the most impacted by ALAN. Here, we focused on the Mediterranean sea urchin Paracentrotus lividus, which has a crucial role in shaping benthic ecosystems. Our objective was to investigate if ALAN affects the nocturnal locomotor behavior of P. lividus. A semi-controlled field study was conducted along a rocky shore near a promenade lit at night. Results suggested a potential impact of ALAN on the locomotor behavior of sea urchins. Individuals of P. lividus tended to move away from the light sources while its directions in dark conditions were uniform. Their locomotor performance, in presence of ALAN, was characterized by shorter latency time, lower sinuosity and higher mean speed at increasing light intensity, with potential cascading effect at the ecosystem level.

Intra-canopy LED lighting outperformed top LED lighting in improving tomato yield and expression of the genes responsible for lycopene, phytoene and vitamin C synthesis.

Greenhouses located at high latitudes and in cloudy areas often experience a low quality and quantity of light, especially during autumn and winter. This low daily light integral (DLI) reduces production rate, quality, and nutritional value of many crops. This study was conducted on Sakhiya RZ F1 tomato plants to evaluate the impact of LED lights on the growth and nutritional value of tomatoes in a greenhouse with low daily light due to cloudy weather. The treatments included LED growth lights in three modes: top lighting, intra-canopy lighting, and combined top and intra-canopy lighting. The results showed that although the combined top and intra-canopy lighting reached the maximum increase in tomato yield, exposure to intra-canopy LED lighting alone outperformed in tomato fruit yield increase (28.46%) than exposure to top LED lighting alone (12.12%) when compared to no supplemental lighting during the entire production year. Intra-canopy exposure demonstrated the highest increase in tomato lycopene (31.3%), while top and intra-canopy lighting exhibited the highest increase in vitamin C content (123.4%) compared to the control. The LED light treatment also had a very positive effect on the expression of genes responsible for metabolic cycles, including Psy1, LCY-ß, and VTC2 genes, which had collinearity with the increase in tomato fruit production.

Classification of melanocytic lesions using direct illumination multispectral imaging.

With rising melanoma incidence and mortality, early detection and surgical removal of primary lesions is essential. Multispectral imaging is a new, non-invasive technique that can facilitate skin cancer detection by measuring the reflectance spectra of biological tissues. Currently, incident illumination allows little light to be reflected from deeper skin layers due to high surface reflectance. A pilot study was conducted at the University Hospital Basel to evaluate, whether multispectral imaging with direct light coupling could extract more information from deeper skin layers for more accurate dignity classification of melanocytic lesions. 27 suspicious pigmented lesions from 23 patients were included (6 melanomas, 6 dysplastic nevi, 12 melanocytic nevi, 3 other). Lesions were imaged before excision using a prototype snapshot mosaic multispectral camera with incident and direct illumination with subsequent dignity classification by a pre-trained multispectral image analysis model. Using incident light, a sensitivity of 83.3% and a specificity of 58.8% were achieved compared to dignity as determined by histopathological examination. Direct light coupling resulted in a superior sensitivity of 100% and specificity of 82.4%. Convolutional neural network classification of corresponding red, green, and blue lesion images resulted in 16.7% lower sensitivity (83.3%, 5/6 malignant lesions detected) and 20.9% lower specificity (61.5%) compared to direct light coupling with multispectral image classification. Our results show that incorporating direct light multispectral imaging into the melanoma detection process could potentially increase the accuracy of dignity classification. This newly evaluated illumination method could improve multispectral applications in skin cancer detection. Further larger studies are needed to validate the camera prototype.

Monitoring Turkey's nighttime light and environmental change.

Nighttime lighting (NTL), population growth, and climate change are critical concerns for Turkey. The intensity of nighttime lights in Turkey has significantly increased in recent years, closely associated with rapid population growth and urban expansion. Areas with higher population density exhibit greater nighttime light presence. Nighttime lighting is directly linked to energy consumption and greenhouse gas (GHG) emissions, contributing significantly to global climate change. The rise in nighttime lighting in Turkey exacerbates climate change effects. In this study, data on NTL were gathered from the NOAA/V21 satellite for 2013-2021, the NOAA/CMCFG satellite for average DMSP-OLS radiance values from 2013 to 2023, and the NOAA/VNP46A2 satellite for BRDF-corrected DMSP-OLS NTL data from 2013 to 2023. Night temperature values were extracted from NOAA and MODIS images, and their correlation with NTL data was analyzed. A moderate relationship was observed between NTL and night land surface temperature (LST) (R, 0.32; p-value < 0.05). Population and greenhouse gas emission data were sourced from the Turkish Statistical Institute (TurkStat). Carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), and fluorinated gases (F-gases) are direct greenhouse gases. A strong correlation was found between NTL and greenhouse gases (R, 0.8; p-value < 0.05). Population density emerges as a significant determinant of nighttime light intensity. These findings underscore the substantial correlation between nighttime light intensity in Turkey, population dynamics, and GHG emissions. The study suggests that NTL data can inform the development of sustainable environmental policies. Mitigating greenhouse gas emissions necessitates controlling population growth and energy consumption, pivotal steps toward environmental sustainability.

Assessment of indoor light-at-night exposure in children and adolescents during schooldays and weekends.

Light-At-Night (LAN) is increasingly recognized and may has adverse health effects on children and adolescents, yet few studies have reported objective indoor LAN exposure levels for children and adolescents. In this study, we measured the indoor LAN exposure levels and duration among 897 children and adolescents aged 6-14 in Beijing, China, using portable photometers during both school days and weekends. Results indicate that the median indoor LAN exposure from 9:00 p.m. to 7:00 a.m. was 5.1 lx, with 31.8% of the subjects experiencing an average exposure above 10 lx. Additionally, from the perspective of cumulative high exposure duration, children and adolescents were exposed to more than 10 lx for approximately 64 min from 9:00 p.m. to 7:00 a.m. During the entire nighttime (from self-reported bedtime to wake-up time), the median exposure was 2.1 lx, with 16.6% averaging exposures above 10 lx. Exposure levels were significantly higher on weekends than on schooldays. Both girls and upper-grade students had higher levels of exposure and longer durations of high exposure. Girls in grade 7 (OR:2.56, 95%CI: 1.68-3.88) experienced the highest LAN exposure in our subjects compared to boys in grade 1-4. Our findings underscore the importance of promoting healthy light exposure behaviors among children and adolescents and reducing their light exposure environments to mitigate the potential health impacts of LAN.

Monitoring day and dark traffic collisions in Toronto neighbourhoods with implications for injury reduction and Vision Zero initiatives: A spatial analysis approach.

The City of Toronto adopted a Vision Zero strategy in 2016 that aims to eliminate deaths and serious injuries from vehicular collisions. The strategy includes policies to improve lighting to reduce collision risks, and past research has suggested lighting as a road safety factor. We apply Bayesian spatial analysis (including Poisson log-normal regression modelling, shared component spatial modelling, and Bayesian spatiotemporal modelling) to publicly available data on traffic collisions where persons are killed or seriously injured (KSI) based on Day/Dark conditions. We assess (1) links between KSI risk and socioeconomic and built environment factors, (2) spatial distributions of relative Day & Dark KSI risk, and (3) area-specific trends in space and time for Day-Dark KSI risk change across Toronto neighbourhoods. Our analysis does not find significant associations between socioeconomic/built environment factors and KSI risk, but we uncover neighbourhoods with heightened Dark KSI risk and pronounced Day-Dark KSI changes compared to Toronto's mean area trend. Findings highlight the need for increased policy attention for impacts of lighting on collisions and provide insight for focus regions for improved Vision Zero policy development.

KineWheel-DeepLabCut Automated Paw Annotation Using Alternating Stroboscopic UV and White Light Illumination.

Uncovering the relationships between neural circuits, behavior, and neural dysfunction may require rodent pose tracking. While open-source toolkits such as DeepLabCut have revolutionized markerless pose estimation using deep neural networks, the training process still requires human intervention for annotating key points of interest in video data. To further reduce human labor for neural network training, we developed a method that automatically generates annotated image datasets of rodent paw placement in a laboratory setting. It uses invisible but fluorescent markers that become temporarily visible under UV light. Through stroboscopic alternating illumination, adjacent video frames taken at 720 Hz are either UV or white light illuminated. After color filtering the UV-exposed video frames, the UV markings are identified and the paw locations are deterministically mapped. This paw information is then transferred to automatically annotate paw positions in the next white light-exposed frame that is later used for training the neural network. We demonstrate the effectiveness of our method using a KineWheel-DeepLabCut setup for the markerless tracking of the four paws of a harness-fixed mouse running on top of the transparent wheel with mirror. Our automated approach, made available open-source, achieves high-quality position annotations and significantly reduces the need for human involvement in the neural network training process, paving the way for more efficient and streamlined rodent pose tracking in neuroscience research.

Practical Advice on Measuring and Applying Light for Laboratory Mammals.

Light is recognized as an important component of the environment for laboratory animals. It supports vision, sets the phase of circadian clocks, and drives wide-ranging adjustments in physiological and behavioral state. Manipulating light is meanwhile a key experimental approach in the fields of vision science and chronobiology. Nevertheless, until recently, there has been no consensus on methods for quantifying light as experienced by laboratory animals. Widely adopted practices employ metrics such as illuminance (units = lux) that are designed to quantify light as experienced by human observers. These weight energy across the spectrum according to a spectral sensitivity profile for human vision that is not widely replicated for non-human species. Recently, a Consensus View was published that proposes methods of light measurement and standardization that take account of these species-specific differences in wavelength sensitivity. Here, we draw upon the contents of that consensus to provide simplified advice on light measurement in laboratory mammal experimentation and husbandry and quantitative guidance on what constitutes appropriate lighting for both visual and circadian function.

A Comprehensive Survey on Emerging Assistive Technologies for Visually Impaired Persons: Lighting the Path with Visible Light Communications and Artificial Intelligence Innovations.

In the context in which severe visual impairment significantly affects human life, this article emphasizes the potential of Artificial Intelligence (AI) and Visible Light Communications (VLC) in developing future assistive technologies. Toward this path, the article summarizes the features of some commercial assistance solutions, and debates the characteristics of VLC and AI, emphasizing their compatibility with blind individuals' needs. Additionally, this work highlights the AI potential in the efficient early detection of eye diseases. This article also reviews the existing work oriented toward VLC integration in blind persons' assistive applications, showing the existing progress and emphasizing the high potential associated with VLC use. In the end, this work provides a roadmap toward the development of an integrated AI-based VLC assistance solution for visually impaired people, pointing out the high potential and some of the steps to follow. As far as we know, this is the first comprehensive work which focuses on the integration of AI and VLC technologies in visually impaired persons' assistance domain.

An Investigation into the Effects of Correlated Color Temperature and Illuminance of Urban Motor Vehicle Road Lighting on Driver Alertness.

Current international optical science research focuses on the non-visual effects of lighting on human cognition, mood, and biological rhythms to enhance overall well-being. Nocturnal roadway lighting, in particular, has a substantial impact on drivers' physiological and psychological states, influencing behavior and safety. This study investigates the non-visual effects of correlated color temperature (CCT: 3000K vs. 4000K vs. 5000K) and illuminance levels (20 lx vs. 30 lx) of urban motor vehicle road lighting on driver alertness during various driving tasks. Conducted between 19:00 and 20:30, the experiments utilized a human-vehicle-light simulation platform. EEG (ß waves), reaction time, and subjective evaluations using the Karolinska Sleepiness Scale (KSS) were measured. The results indicated that the interaction between CCT and illuminance, as well as between CCT and task type, significantly influenced driver alertness. However, no significant effect of CCT and illuminance on reaction time was observed. The findings suggest that higher illuminance (30 lx) combined with medium CCT (4000K) effectively reduces reaction time. This investigation enriches related research, provides valuable reference for future studies, and enhances understanding of the mechanisms of lighting's influence on driver alertness. Moreover, the findings have significant implications for optimizing the design of urban road lighting.

A Rapid Nanofocusing Method for a Deep-Sea Gene Sequencing Microscope Based on Critical Illumination.

In the deep-sea environment, the volume available for an in-situ gene sequencer is severely limited. In addition, optical imaging systems are subject to real-time, large-scale defocusing problems caused by ambient temperature fluctuations and vibrational perturbations. To address these challenges, we propose an edge detection algorithm for defocused images based on grayscale gradients and establish a defocus state detection model with nanometer resolution capabilities by relying on the inherent critical illumination light field. The model has been applied to a prototype deep-sea gene sequencing microscope with a 20× objective. It has demonstrated the ability to focus within a dynamic range of ±40 µm with an accuracy of 200 nm by a single iteration within 160 ms. By increasing the number of iterations and exposures, the focusing accuracy can be refined to 78 nm within a dynamic range of ±100 µm within 1.2 s. Notably, unlike conventional photoelectric hill-climbing, this method requires no additional hardware and meets the wide dynamic range, speed, and high-accuracy autofocusing requirements of deep-sea gene sequencing in a compact form factor.

Illumination Intelligent Adaptation and Analysis Framework: A comprehensive solution for enhancing nighttime driving fatigue monitoring.

Nighttime driving presents a critical challenge to road safety due to insufficient lighting and increased risk of driver fatigue. Existing methods for monitoring driver fatigue, mainly focusing on behavioral analysis and biometric monitoring, face significant challenges under low-light conditions. Their effectiveness, especially in dynamic lighting environments, is limited by their dependency on specific environmental conditions and active driver participation, leading to reduced accuracy and practicality in real-world scenarios. This study introduces a novel 'Illumination Intelligent Adaptation and Analysis Framework (IIAAF)', aimed at addressing these limitations and enhancing the accuracy and practicality of driver fatigue monitoring under nighttime low-light conditions. The IIAAF framework employs a multidimensional technology integration, including comprehensive body posture analysis and facial fatigue feature detection, per-pixel dynamic illumination adjustment technology, and a light variation feature learning system based on Convolutional Neural Networks (CNN) and time-series analysis. Through this integrated approach, the framework is capable of accurately capturing subtle fatigue signals in nighttime driving environments and adapting in real-time to rapid changes in lighting conditions. Experimental results on two independent datasets indicate that the IIAAF framework significantly improves the accuracy of fatigue detection under nighttime low-light conditions. This breakthrough not only enhances the effectiveness of driving assistance systems but also provides reliable scientific support for reducing the risk of accidents caused by fatigued driving. These research findings have significant theoretical and practical implications for advancing intelligent driving assistance technology and improving nighttime road safety.

Colour expectations across illumination changes.

This study investigates human expectations towards naturalistic colour changes under varying illuminations. Understanding colour expectations is key to both scientific research on colour constancy and applications of colour and lighting in art and industry. We reanalysed data from asymmetric colour matches of a previous study and found that colour adjustments tended to align with illuminant-induced colour shifts predicted by naturalistic, rather than artificial, illuminants and reflectances. We conducted three experiments using hyperspectral images of naturalistic scenes to test if participants judged colour changes based on naturalistic illuminant and reflectance spectra as more plausible than artificial ones, which contradicted their expectations. When we consistently manipulated the illuminant (Experiment 1) and reflectance (Experiment 2) spectra across the whole scene, observers chose the naturalistic renderings significantly above the chance level (>25 %) but barely more often than any of the three artificial ones, collectively (>50 %). However, when we manipulated only one object/area's reflectance (Experiment 3), observers more reliably identified the version in which the object had a naturalistic reflectance like the rest of the scene. Results from Experiments 2-3 and additional analyses suggested that relational colour constancy strongly contributed to observer expectations, and stable cone-excitation ratios are not limited to naturalistic illuminants and reflectances but also occur for our artificial renderings. Our findings indicate that relational colour constancy and prior knowledge about surface colour shifts help to disambiguate surface colour identity under illumination changes, enabling human observers to recognise surface colours reliably in naturalistic conditions. Additionally, relational colour constancy may even be effective in many artificial conditions.

The adaptive global effect: Luminance contrast modulates the global effect zone.

When two peripheral objects are presented in close proximity, saccades towards one of these objects land at a weighted average location between the two objects. This phenomenon, known as the 'global effect' or 'saccade averaging', disappears when the distance between the objects increases. When objects are further apart, outside the averaging zone, saccades land on one of the objects with little or no saccade averaging. Although it is known that the strength of the global effect is dependent on the specific features of the two objects, it is unclear if the size of the zone in which averaging can occur (i.e., the averaging zone) is adaptive. The aim of the current study was to investigate whether the size of the averaging zone adapts to variations in object luminance contrast of the objects. In order to systematically assess changes in the averaging zone, in two experiments, observers made saccadic eye movements while the luminance of the target and the distractor varied. We report three major findings: 1) When a distractor was more luminant relative to the target, the averaging zone increased (Exp. 1). Notably, saccade averaging never entirely ceased to exist, even for remote distractors. 2) When target and distractor were equiluminant, the averaging zone did not change with absolute luminance (Exp. 2). 3) Higher (relative and absolute) luminance increased the averaging zone especially for shorter saccadic response times (SRT). We conclude that the averaging zone is adaptive and becomes larger with increasing relative luminance and especially when SRTs are short.

Adaptation of indoor ornamental plants to various lighting levels in growth chambers simulating workplace environments.

Despite the growing interest in indoor greenery and its positive effects on occupants' well-being, there is limited knowledge on the optimal light levels for indoor plants that ensure energy efficiency and sustainable growth. This study explored the survival of ornamental plants under low-light conditions typical of indoor workplaces without daylight and investigated the impact of increased light intensity or extended day length on their growth. Three species of foliage plants (Epipremnum aureum, Pachira aquatica, and Rhaphidophora tetrasperma) were cultivated in growth chambers with three different lighting schemes. The results showed that plants sustained growth with 6.8 µmol m-2 s-1 white LED light for 9 h/day, suggesting that extra lighting might not be necessary for shade-tolerant species in offices. In this environment, plants maintained efficient photosynthesis under low illumination by increasing their specific leaf area. Elevating the light to 20.1 µmol m-2 s-1 and extending the day length to 18 h/day enhanced the plants' relative growth rate. Climbing plants allocated more biomass to stems, resulting in a lower leaf weight ratio and noticeably altering their appearance. This study demonstrates that customized lighting strategies effectively support indoor greening goals, like adjusting intensity for energy savings or adding light for greening large spaces.

Numerical simulation application in occupational health studies: a review.

Most occupational hazardous agents in workplaces should be evaluated and controlled. Different methods exist for identifying, evaluating and controlling these agents, such as numerical simulation tools. Numerical simulations can help experts to improve occupational health. Due to the importance and abilities of numerical simulations, this study divided occupational hazardous agents into 10 subgroups. These subgroups included air pollution, ventilation, respiratory airways, noise and vibration, lighting, radiation, ergonomics, fire and explosion, risk assessment and personal protective equipment. Recent research studies in each subgroup were then reviewed, and the codes and software used in simulations were determined. The results show that Fluent software and k-ϵ turbulence models are the most used in occupational health studies simulations. Today, different codes and software have been developed for simulation, and we suggest their use in occupational health studies.