scholarly journals The Calculated Circadian Effects of Light Exposure from Commuting

2021 ◽  
Vol 11 (24) ◽  
pp. 11846
Author(s):  
Yihan Lu ◽  
Wenye Hu ◽  
Wendy Davis
Keyword(s):  
Circadian Rhythms ◽  
Light Exposure ◽  
Weather Conditions ◽  
Health Problems ◽  
Spectral Irradiance ◽  
Metropolitan Region ◽  
Circadian Regulation ◽  
Lighting Conditions ◽  
Indoor Lighting ◽  
Daylight Exposure

Light entrains human circadian rhythms, but increased time spent indoors and decreased daylight exposure may disrupt human circadian regulation and cause health problems. Much research is focused on improving indoor lighting conditions to minimize the adverse circadian impact of electric lights, and few studies investigate the circadian impact of daylight during the incidental time that people spend outdoors. For instance, when people commute from home to work, they are exposed to daylight. The purpose of this study is to investigate daylight’s impact on commuters’ circadian rhythms. Measurements of the illuminance and the spectral irradiance distribution (SID) of daylight were taken for three modes of commuting: driving, riding on trains, and walking; and under different weather conditions, on different days, and at different locations throughout the summer and autumn in the Sydney metropolitan region in Australia. With the SID data, three metrics were calculated to estimate the circadian impacts: α-opic irradiance, circadian stimulus (CS), and equivalent melanopic lux (EML). The results suggest that driving or walking on sunny or cloudy days and riding trains on sunny days are beneficial for the commuters’ circadian synchronization.

scholarly journals VALIDATION OF SPECTRAL SIMULATION TOOLS FOR THE PREDICTION OF INDOOR ELECTRIC LIGHT EXPOSURE

2021 ◽  
Author(s):  
C. Pierson ◽  
M. Gkaintatzi-Masouti ◽  
M.P.J. Aarts ◽  
M. Andersen
Keyword(s):  
Light Exposure ◽  
Spectral Characteristics ◽  
Spectral Irradiance ◽  
Spectral Simulation ◽  
Simulation Tools ◽  
Lighting Conditions ◽  
Spectral Simulations ◽  
Electric Light ◽  
Indoor Lighting

As the interest in design applications related to responses to light beyond vision is growing, two simulation tools, ALFA and Lark, have been developed to incorporate spectral characteristics of light in the evaluation of indoor lighting conditions. The spectral characteristics of light are of particular relevance when studying ipRGC-influenced responses. This paper aims to assess the reliability of these tools in predicting indoor spectral irradiance specifically from electric lighting. Spectral irradiance was measured under three indoor electric lighting scenarios and compared against spectral irradiance simulated in ALFA and Lark. While the outcomes of the study tend to show that ALFA is both more accurate and faster, rather large errors were found for spectral irradiance (-28.6% to 33.4%). In comparison to a prior study focusing on daylighting, these results seem to indicate that spectral simulations of electrically lit scenes are generally less accurate than those of daylit scenes with these tools.

Range of entrainment of rat circadian rhythms to sinusoidal light-intensity cycles

2000 ◽  
Vol 278 (5) ◽  
pp. R1148-R1156 ◽  
Author(s):  
Setsuo Usui ◽  
Yasuro Takahashi ◽  
Terue Okazaki
Keyword(s):  
Circadian Rhythms ◽  
Light Intensity ◽  
Lower Limit ◽  
Phase Angle ◽  
Light Exposure ◽  
Sprague Dawley ◽  
Lighting Conditions ◽  
Behavioral Rhythm ◽  
Sprague Dawley Rats ◽  
Daily Cycles

The range of entrainment of the circadian behavioral rhythm was compared between two groups of Sprague-Dawley rats (each n = 10) exposed to daily cycles of rectangular light-dark alternation (LD) and sinusoidal fluctuations of light intensity (SINE), respectively. The maximum illuminance (20 lx), the minimum illuminance (0.01 lx), and the total amount of light exposure per cycle were the same under the two lighting conditions. The periods (Ts) of both lighting cycles were lengthened stepwise from 24 through 25, 26, 26.5, 27, 27.5, and 28 h to 28.5 h in experiment 1 and were shortened stepwise from 24 through 23.5, 23, and 22.5 h to 22 h in experiment 2. Each T cycle lasted for 30 cycles. In experiment 1, 60% of rats under the LD condition entrained up to T = 28.5 h, whereas 50% of rats under the SINE condition entrained up to T = 28.5 h. In experiment 2, no animal under the LD condition entrained to T < 23.5 h, whereas 40% of rats under the SINE condition entrained down to T = 23 h and 20% of rats remained to entrain down to T = 22 h cycles. The phase angle of entrainment was systematically changed, depending on T under both conditions. These results suggest that the lower limit of entrainment is expanded under the SINE condition compared with the LD condition.

scholarly journals Light and chronobiology: implications for health and disease

2012 ◽  
Vol 14 (4) ◽  
pp. 448-453 ◽  
Keyword(s):  
Cognitive Performance ◽  
Light Exposure ◽  
Biological Clock ◽  
Spectral Composition ◽  
Light Therapy ◽  
Lighting Conditions ◽  
Environmental Light ◽  
Health And Disease ◽  
Peripheral Clocks ◽  
Indoor Lighting

Environmental light synchronizes the primary mammalian biological clock in the suprachiasmatic nuclei, as well as many peripheral clocks in tissues and cells, to the solar 24-hour day. Light is the strongest synchronizing agent (zeitgeber) for the circadian system, and therefore keeps most biological and psychological rhythms internally synchronized, which is important for optimum function. Circadian sleep-wake disruptions and chronic circadian misalignment, as often observed in psychiatric and neurodegenerative illness, can be treated with light therapy. The beneficial effect on circadian synchronization, sleep quality, mood, and cognitive performance depends on timing, intensity, and spectral composition of light exposure. Tailoring and optimizing indoor lighting conditions may be an approach to improve wellbeing, alertness, and cognitive performance and, in the long term, producing health benefits.

Circadian rhythms of temperature and activity in obese and lean Zucker rats

1995 ◽  
Vol 269 (5) ◽  
pp. R1038-R1043 ◽  
Author(s):  
D. M. Murakami ◽  
B. A. Horwitz ◽  
C. A. Fuller
Keyword(s):  
Circadian Rhythms ◽  
Female Rats ◽  
Zucker Rats ◽  
Circadian Regulation ◽  
Circadian Timing ◽  
Lighting Conditions ◽  
Timing System ◽  
Circadian Timing System ◽  
Obese Zucker Rats ◽  
Normal Light

The circadian timing system is important in the regulation of feeding and metabolism, both of which are aberrant in the obese Zucker rat. This study tested the hypothesis that these abnormalities involve a deficit in circadian regulation by examining the circadian rhythms of body temperature and activity in lean and obese Zucker rats exposed to normal light-dark cycles, constant light, and constant dark. Significant deficits in both daily mean and circadian amplitude of temperature and activity were found in obese Zucker female rats relative to lean controls in all lighting conditions. However, the circadian period of obese Zucker rats did not exhibit differences relative to lean controls in either of the constant lighting conditions. These results indicate that although the circadian regulation of temperature and activity in obese Zucker female rats is in fact depressed, obese rats do exhibit normal entrainment and pacemaker functions in the circadian timing system. The results suggest a deficit in the process that generates the amplitude of the circadian rhythm.

Circadian regulation of locomotor activity and skeletal muscle gene expression in the horse

2010 ◽  
Vol 109 (5) ◽  
pp. 1328-1336 ◽  
Author(s):  
Ann-Marie Martin ◽  
Jeffrey A. Elliott ◽  
Pat Duffy ◽  
Catriona M. Blake ◽  
Sarra Ben Attia ◽  
...  
Keyword(s):  
Gene Expression ◽  
Skeletal Muscle ◽  
Locomotor Activity ◽  
Circadian Rhythms ◽  
Environmental Changes ◽  
Light Exposure ◽  
Circadian Regulation ◽  
Circadian Pattern ◽  
Muscle Gene Expression ◽  
Muscle Gene

Circadian rhythms are innate 24-h cycles in behavioral and biochemical processes that permit physiological anticipation of daily environmental changes. Elucidating the relationship between activity rhythms and circadian patterns of gene expression may contribute to improved human and equine athletic performance. Six healthy, untrained mares were studied to determine whether locomotor activity behavior and skeletal muscle gene expression reflect endogenous circadian regulation. Activity was recorded for three consecutive 48-h periods: as a group at pasture (P), and individually stabled under a light-dark (LD) cycle and in constant darkness (DD). Halter-mounted Actiwatch-L data-loggers recorded light exposure and motor activity. Analysis of mean activity (average counts/min, activity bouts/day, average bout length) and cosinor parameters (acrophase, amplitude, mesor, goodness of fit) revealed a predominantly ultradian (8.9 ± 0.7 bouts/24 h) and weakly circadian pattern of activity in all three conditions (P, LD, DD). A more robust circadian pattern was observed during LD and DD. Muscle biopsies were obtained from the middle gluteal muscles every 4 h for 24 h under DD. One-way qRT-PCR results confirmed the circadian expression ( P < 0.05) of six core clock genes ( Arntl, Per1, Per2, Nr1d1, Nr1d2, Dbp) and the muscle-specific transcript, Myf6. Additional genes, Ucp3, Nrip1, and Vegfa, demonstrated P values approaching significance. These findings demonstrate circadian regulation of muscle function and imply that human management regimes may strengthen, or unmask, equine circadian behavioral outputs. As exercise synchronizes circadian rhythms, our findings provide a basis for future work determining peak times for training and competing horses, to reduce injury and to achieve optimal performance.

Nonphotic entrainment of the human circadian pacemaker

1998 ◽  
Vol 274 (4) ◽  
pp. R991-R996 ◽  
Author(s):  
Elizabeth B. Klerman ◽  
David W. Rimmer ◽  
Derk-Jan Dijk ◽  
Richard E. Kronauer ◽  
Joseph F. Rizzo ◽  
...  
Keyword(s):  
Circadian Rhythms ◽  
Light Exposure ◽  
Core Body Temperature ◽  
Biological Clock ◽  
Bright Light ◽  
Circadian Pacemaker ◽  
Temperature Rhythms ◽  
Blind Individuals ◽  
Nonphotic Entrainment ◽  
Core Body

In organisms as diverse as single-celled algae and humans, light is the primary stimulus mediating entrainment of the circadian biological clock. Reports that some totally blind individuals appear entrained to the 24-h day have suggested that nonphotic stimuli may also be effective circadian synchronizers in humans, although the nonphotic stimuli are probably comparatively weak synchronizers, because the circadian rhythms of many totally blind individuals “free run” even when they maintain a 24-h activity-rest schedule. To investigate entrainment by nonphotic synchronizers, we studied the endogenous circadian melatonin and core body temperature rhythms of 15 totally blind subjects who lacked conscious light perception and exhibited no suppression of plasma melatonin in response to ocular bright-light exposure. Nine of these fifteen blind individuals were able to maintain synchronization to the 24-h day, albeit often at an atypical phase angle of entrainment. Nonphotic stimuli also synchronized the endogenous circadian rhythms of a totally blind individual to a non-24-h schedule while living in constant near darkness. We conclude that nonphotic stimuli can entrain the human circadian pacemaker in some individuals lacking ocular circadian photoreception.

Influence of the perceived size of a light source on non-visual effects in humans

2020 ◽  
Vol 9 (6) ◽  
pp. 385-393
Author(s):  
Arvid Niemeyer ◽  
Lucia Rottmair ◽  
Cornelius Neumann ◽  
Cornelius Möckel
Keyword(s):  
Working Memory ◽  
Light Exposure ◽  
Error Rates ◽  
Positive Contribution ◽  
Measurement Point ◽  
Visual Effects ◽  
Lighting Conditions ◽  
Light Measurement ◽  
And Performance ◽  
Main Effects

AbstractLight not only enables humans to perceive their surroundings, but also influences their sleep–wake cycle, mood, concentration and performance. Targeted use of these so called nonvisual effects could also have a positive contribution in automobiles by keeping passengers alert, minimizing error rates or bootsting attention in general. Since construction space in vehicle interios is scarce, this study compared the influence of differently-sized light panels and thus solid angles on nonvisual effects. In a counterbalanced order, 32 volunteers were exposed to three lighting conditions in the morning: baseline (12 lx, 2200 K), small (200 lx, 6500 K, 0.05 sr) and large (200 lx, 6500 K, 0.44 sr). During each session of 60 min, alertness, concentration and working memory were assessed before and during light exposure. After data analysis no significant main effects of light, measurement point or interaction between light and measurement point could be seen.

scholarly journals Practical limitations of lane detection algorithm based on Hough transform in challenging scenarios

2021 ◽  
Vol 18 (2) ◽  
pp. 172988142110087
Author(s):  
Qiao Huang ◽  
Jinlong Liu
Keyword(s):  
Hough Transform ◽  
Detection Rate ◽  
Real Life ◽  
Weather Conditions ◽  
Autonomous Driving ◽  
Detection Algorithm ◽  
Lane Detection ◽  
Search Range ◽  
Range Restriction ◽  
Lighting Conditions

The vision-based road lane detection technique plays a key role in driver assistance system. While existing lane recognition algorithms demonstrated over 90% detection rate, the validation test was usually conducted on limited scenarios. Significant gaps still exist when applied in real-life autonomous driving. The goal of this article was to identify these gaps and to suggest research directions that can bridge them. The straight lane detection algorithm based on linear Hough transform (HT) was used in this study as an example to evaluate the possible perception issues under challenging scenarios, including various road types, different weather conditions and shades, changed lighting conditions, and so on. The study found that the HT-based algorithm presented an acceptable detection rate in simple backgrounds, such as driving on a highway or conditions showing distinguishable contrast between lane boundaries and their surroundings. However, it failed to recognize road dividing lines under varied lighting conditions. The failure was attributed to the binarization process failing to extract lane features before detections. In addition, the existing HT-based algorithm would be interfered by lane-like interferences, such as guardrails, railways, bikeways, utility poles, pedestrian sidewalks, buildings and so on. Overall, all these findings support the need for further improvements of current road lane detection algorithms to be robust against interference and illumination variations. Moreover, the widely used algorithm has the potential to raise the lane boundary detection rate if an appropriate search range restriction and illumination classification process is added.

scholarly journals Light, Alertness, and Alerting Effects of White Light: A Literature Overview

2018 ◽  
Vol 33 (6) ◽  
pp. 589-601 ◽  
Author(s):  
Renske Lok ◽  
Karin C. H. J. Smolders ◽  
Domien G. M. Beersma ◽  
Yvonne A. W. de Kort
Keyword(s):  
White Light ◽  
Light Exposure ◽  
Neural Mechanisms ◽  
Dependent Manner ◽  
Experimental Paradigm ◽  
Research Paradigms ◽  
Lighting Conditions ◽  
Literature Overview ◽  
Dose Dependent ◽  
As Effects

Light is known to elicit non–image-forming responses, such as effects on alertness. This has been reported especially during light exposure at night. Nighttime results might not be translatable to the day. This article aims to provide an overview of (1) neural mechanisms regulating alertness, (2) ways of measuring and quantifying alertness, and (3) the current literature specifically regarding effects of different intensities of white light on various measures and correlates of alertness during the daytime. In general, the present literature provides inconclusive results on alerting effects of the intensity of white light during daytime, particularly for objective measures and correlates of alertness. However, the various research paradigms employed in earlier studies differed substantially, and most studies tested only a limited set of lighting conditions. Therefore, the alerting potential of exposure to more intense white light should be investigated in a systematic, dose-dependent manner with multiple correlates of alertness and within one experimental paradigm over the course of day.

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