Sustained effects of prior red light on pupil diameter and vigilance during subsequent darkness

Environmental light can exert potent effects on physiology and behaviour, including pupil size, vigilance and sleep. Previous work showed that these non-image forming effects can last long beyond discontinuation of short -wavelength light exposure. The possible functional effects after switching off long -wavelength light, however, have been insufficiently characterized. In a series of controlled experiments in healthy adult volunteers, we evaluated the effects of five minutes of intense red light on physiology and performance during subsequent darkness. As compared to prior darkness, prior red light induced a subsequent sustained pupil dilation. Prior red light also increased subsequent heart rate and heart rate variability when subjects were asked to perform a sustained vigilance task during the dark exposure. While these changes suggest an increase in the mental effort required for the task, it could not prevent a post-red slowing of response speed. The suggestion that exposure to intense red light affects vigilance during subsequent darkness, was confirmed in a controlled polysomnographic study that indeed showed a post-red facilitation of sleep onset. Our findings suggest the possibility of using red light as a nightcap.

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Prediction Of Shiftworker Alertness, Sleep, And Circadian Phase Using A Model Of Arousal Dynamics Constrained By Shift Schedules And Light Exposure

SLEEP ◽

10.1093/sleep/zsab146 ◽

2021 ◽

Author(s):

Stuart A Knock ◽

Michelle Magee ◽

Julia E Stone ◽

Saranea Ganesan ◽

Megan D Mulhall ◽

...

Keyword(s):

Light Exposure ◽

Night Shift ◽

Vigilance Task ◽

Study Data ◽

Accurate Prediction ◽

Environmental Constraints ◽

Wake Time ◽

Circadian Phase ◽

Shift Schedules ◽

And Performance

Abstract Study Objectives The study aimed to, for the first time, (i) compare sleep, circadian phase, and alertness of Intensive Care Unit (ICU) nurses working rotating shifts with those predicted by a model of arousal dynamics; and (ii) investigate how different environmental constraints affect predictions and agreement with data. Methods The model was used to simulate individual sleep-wake cycles, urinary 6-sulphatoxymelatonin (aMT6s) profiles, subjective sleepiness on the Karolinska Sleepiness Scale (KSS), and performance on a Psychomotor Vigilance Task (PVT) of 21 ICU nurses working day, evening, and night shifts. Combinations of individual shift schedules, forced wake time before/after work and lighting, were used as inputs to the model. Predictions were compared to empirical data. Simulations with self-reported sleep as an input were performed for comparison. Results All input constraints produced similar prediction for KSS, with 56-60% of KSS scores predicted within ±1 on a day and 48-52% on a night shift. Accurate prediction of an individual’s circadian phase required individualised light input. Combinations including light information predicted aMT6s acrophase within ±1 h of the study data for 65% and 35-47% of nurses on diurnal and nocturnal schedules. Minute-by-minute sleep-wake state overlap between the model and the data was between 81±6% and 87±5% depending on choice of input constraint. Conclusions The use of individualised environmental constraints in the model of arousal dynamics allowed for accurate prediction of alertness, circadian phase and sleep for more than half of the nurses. Individual differences in physiological parameters will need to be accounted for in the future to further improve predictions.

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Light at Night and Measures of Alertness and Performance

Biological Research For Nursing ◽

10.1177/1099800415572873 ◽

2015 ◽

Vol 18 (1) ◽

pp. 90-100 ◽

Cited By ~ 38

Author(s):

Mariana G. Figueiro ◽

Levent Sahin ◽

Brittany Wood ◽

Barbara Plitnick

Keyword(s):

White Light ◽

Light Exposure ◽

Red Light ◽

Reaction Times ◽

Light At Night ◽

Improve Performance ◽

Practical Applications ◽

Circadian Phase ◽

Dim Light ◽

And Performance

Rotating-shift workers, particularly those working at night, are likely to experience sleepiness, decreased productivity, and impaired safety while on the job. Light at night has been shown to have acute alerting effects, reduce sleepiness, and improve performance. However, light at night can also suppress melatonin and induce circadian disruption, both of which have been linked to increased health risks. Previous studies have shown that long-wavelength (red) light exposure increases objective and subjective measures of alertness at night, without suppressing nocturnal melatonin. This study investigated whether exposure to red light at night would not only increase measures of alertness but also improve performance. It was hypothesized that exposure to both red (630 nm) and white (2,568 K) lights would improve performance but that only white light would significantly affect melatonin levels. Seventeen individuals participated in a 3-week, within-subjects, nighttime laboratory study. Compared to remaining in dim light, participants had significantly faster reaction times in the GO/NOGO test after exposure to both red light and white light. Compared to dim light exposure, power in the alpha and alpha-theta regions was significantly decreased after exposure to red light. Melatonin levels were significantly suppressed by white light only. Results show that not only can red light improve measures of alertness, but it can also improve certain types of performance at night without affecting melatonin levels. These findings could have significant practical applications for nurses; red light could help nurses working rotating shifts maintain nighttime alertness, without suppressing melatonin or changing their circadian phase.

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0172 Blue-Light Blockers and Sleep: A Meta-Analysis of Intervention Studies

SLEEP ◽

10.1093/sleep/zsaa056.170 ◽

2020 ◽

Vol 43 (Supplement_1) ◽

pp. A68-A69

Author(s):

A Shechter ◽

K A Quispe ◽

J S Mizhquiri Barbecho ◽

L Falzon

Keyword(s):

Short Wavelength ◽

Light Exposure ◽

Meta Analysis ◽

Electronic Devices ◽

Sleep Onset ◽

Sleep Time ◽

Combined Effect ◽

Light Emitting ◽

Short Wavelength Light ◽

Wavelength Light

Abstract Introduction Sleep and circadian physiology are influenced by external light, particularly within the short-wavelength portion of the visible spectrum (~450–480 nm). Most personal light-emitting electronic devices (e.g., tablets, smartphones, computers) are enriched in this so-called “blue” light. Interventions to reduce short-wavelength light exposure to the eyes before bedtime may help mitigate adverse effects of light-emitting electronic devices on sleep. Methods We conducted a meta-analysis of intervention studies on the effects of wearing color-tinted lenses (e.g., orange or amber) in frames in the evening before sleep to selectively filter short-wavelength light exposure to the eyes. Outcomes were self-reported or objective (wrist-accelerometer) measures of nocturnal sleep. Databases (MEDLINE, EMBASE, Cochrane Library, PsycINFO, CINAHL, AMED) were searched from inception to November 2019. PROSPERO Registration: CRD42018105854. Results Ten studies were identified (7 randomized controlled trials; 3 before-after studies). Findings of individual studies were inconsistent, with some showing benefit and others showing no effect of intervention. For objective sleep onset latency, there was a significant modest-sized combined effect (Hedge’s g=-0.52, 95% CI: -1.27-0.24, Z=-2.94, p=0.003, I2=16.6%, k=3). There was a minor but non-statistically significant combined effect for objective sleep efficiency (Hedge’s g=0.24, 95% CI: -0.16–0.64, Z=1.69, p=0.09, I2=23.7%, k=5). There were no significant combined effects for objective measures of total sleep time and wake after sleep onset. For self-reported total sleep time, there was a statistically significant medium-sized combined effect (Hedge’s g=0.61, 95% CI: 0.14–1.09, Z=5.56, p<0.01, I2=0%, k=3). Conclusion There is mixed evidence that this approach can improve sleep. Relatively few studies have been conducted, and most did not assess light levels or melatonin. The “blue-blocker” intervention may be particularly useful in individuals with insomnia, delayed sleep phase syndrome, or attention-deficit hyperactive disorder. Considering the ubiquitousness of short wavelength-enriched light sources and the potential for widespread sleep disturbance, future controlled studies examining the efficacy of this approach to improve sleep are warranted. Support N/A

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Diurnal Rhythm of Plasma Melatonin Concentration in the Domestic Turkey and Its Regulation by Light and Endogenous Oscillators

Animals ◽

10.3390/ani10040678 ◽

2020 ◽

Vol 10 (4) ◽

pp. 678 ◽

Cited By ~ 1

Author(s):

Magdalena Prusik ◽

Bogdan Lewczuk

Keyword(s):

Diurnal Rhythm ◽

Light Exposure ◽

Red Light ◽

Secretory Activity ◽

Continuous Darkness ◽

Night Time ◽

Melatonin Concentration ◽

Plasma Melatonin ◽

Environmental Light ◽

The Difference

The aim of this study was to characterize the diurnal rhythm of plasma melatonin (MLT) concentration and its regulation by light and endogenous oscillators in 10-week-old domestic turkeys. Three experiments were performed to examine (i) the course of daily changes in plasma MLT concentration in turkeys kept under a 12 h light: 12 h dark (12L:12D) cycle; (ii) the influence of night-time light exposure lasting 0.5, 1, 2, or 3 h on the plasma MLT level; and (iii) the occurrence of circadian fluctuations in plasma MLT levels in birds kept under continuous dim red light and the ability of turkeys to adapt their pineal secretory activity to a reversed light-dark cycle (12D:12L). The plasma MLT concentration was measured with a direct radioimmunoassay. The plasma MLT concentration in turkeys kept under a 12L:12D cycle changed significantly in a daily rhythm. It was low during the photophase and increased stepwise after the onset of darkness to achieve the maximal level in the middle of the scotophase. Next, it decreased during the second half of the night. The difference between the lowest level of MLT and the highest level was approximately 18-fold. The exposure of turkeys to light during the scotophase caused a rapid, large decrease in plasma MLT concentration. The plasma MLT concentration decreased approximately 3- and 10-fold after 0.5 and 1 h of light exposure, respectively, and reached the day-time level after 2 h of exposure. In turkeys kept under continuous darkness, the plasma MLT level was approximately 2.5-fold higher at 02:00 h than at 14:00 h. In birds kept under 12D:12L, the plasma MLT level was significantly higher at 14:00 h than at 02:00 h. The results showed that plasma MLT concentrations in 10-week-old turkeys have a prominent diurnal rhythm, which is endogenously generated and strongly influenced by environmental light.

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Wearable Technologies in Field Hockey Competitions: A Scoping Review

Sensors ◽

10.3390/s21155242 ◽

2021 ◽

Vol 21 (15) ◽

pp. 5242

Author(s):

Jolene Ziyuan Lim ◽

Alexiaa Sim ◽

Pui Wah Kong

Keyword(s):

Heart Rate ◽

Inertial Sensors ◽

Wearable Devices ◽

Field Hockey ◽

Heart Rate Monitors ◽

Search Terms ◽

Physiological Demands ◽

And Performance ◽

Future Work ◽

Skin Temperatures

The aim of this review is to investigate the common wearable devices currently used in field hockey competitions, and to understand the hockey-specific parameters these devices measure. A systematic search was conducted by using three electronic databases and search terms that included field hockey, wearables, accelerometers, inertial sensors, global positioning system (GPS), heart rate monitors, load, performance analysis, player activity profiles, and competitions from the earliest record. The review included 39 studies that used wearable devices during competitions. GPS units were found to be the most common wearable in elite field hockey competitions, followed by heart rate monitors. Wearables in field hockey are mostly used to measure player activity profiles and physiological demands. Inconsistencies in sampling rates and performance bands make comparisons between studies challenging. Nonetheless, this review demonstrated that wearable devices are being used for various applications in field hockey. Researchers, engineers, coaches, and sport scientists can consider using GPS units of higher sampling rates, as well as including additional variables such as skin temperatures and injury associations, to provide a more thorough evaluation of players’ physical and physiological performances. Future work should include goalkeepers and non-elite players who are less studied in the current literature.

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Indices of Heart Rate Variability and Performance During a Response-Conflict Task Are Differently Associated With ADHD and Autism

Journal of Attention Disorders ◽

10.1177/1087054720972793 ◽

2021 ◽

pp. 108705472097279

Author(s):

Alessio Bellato ◽

Iti Arora ◽

Puja Kochhar ◽

Chris Hollis ◽

Madeleine J. Groom

Keyword(s):

Heart Rate ◽

Heart Rate Variability ◽

Sensory Information ◽

Response Conflict ◽

Mediation Model ◽

Conflict Task ◽

Accurate Performance ◽

And Performance ◽

Comorbid Adhd ◽

The Relationship

We investigated autonomic arousal, attention and response conflict, in ADHD and autism. Heart rate variability (HRV), and behavioral/electrophysiological indices of performance, were recorded during a task with low and high levels of response conflict in 78 children/adolescents (7–15 years old) with ADHD, autism, comorbid ADHD+autism, or neurotypical. ANOVA models were used to investigate effects of ADHD and autism, while a mediation model was tested to clarify the relationship between ADHD and slower performance. Slower and less accurate performance characterized ADHD and autism; however, atypical electrophysiological indices differently characterized these conditions. The relationship between ADHD and slower task performance was mediated by reduced HRV in response to the cue stimulus. Autonomic hypo-arousal and difficulties in mobilizing energetic resources in response to sensory information (associated with ADHD), and atypical electrophysiological indices of information processing (associated with autism), might negatively affect cognitive performance in those with ADHD+autism.

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Field Monitoring the Effects of Overnight Shift Work on Specialist Tactical Police Training with Heart Rate Variability Analysis

Sustainability ◽

10.3390/su13147895 ◽

2021 ◽

Vol 13 (14) ◽

pp. 7895

Author(s):

Colin Tomes ◽

Ben Schram ◽

Robin Orr

Keyword(s):

Heart Rate ◽

Heart Rate Variability ◽

Shift Work ◽

Emergency Response ◽

Police Training ◽

Heart Rate Variability Analysis ◽

Response Team ◽

Hrv Analysis ◽

And Performance ◽

Personnel Allocation

Police work exposes officers to high levels of stress. Special emergency response team (SERT) service exposes personnel to additional demands. Specifically, the circadian cycles of SERT operators are subject to disruption, resulting in decreased capacity to compensate in response to changing demands. Adaptive regulation loss can be measured through heart rate variability (HRV) analysis. While HRV Trends with health and performance indicators, few studies have assessed the effect of overnight shift work on HRV in specialist police. Therefore, this study aimed to determine the effects overnight shift work on HRV in specialist police. HRV was analysed in 11 SERT officers and a significant (p = 0.037) difference was found in pRR50 levels across the training day (percentage of R-R intervals varying by >50 ms) between those who were off-duty and those who were on duty the night prior. HRV may be a valuable metric for quantifying load holistically and can be incorporated into health and fitness monitoring and personnel allocation decision making.

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098 Effects of Metameric Display-Light on Alertness, Vigilance and Melatonin

SLEEP ◽

10.1093/sleep/zsab072.097 ◽

2021 ◽

Vol 44 (Supplement_2) ◽

pp. A40-A41

Author(s):

Isabel Schöllhorn ◽

Oliver Stefani ◽

Manuel Spitschan ◽

Robert Lucas ◽

Christian Cajochen

Keyword(s):

Statistical Power ◽

Light Exposure ◽

Vigilance Task ◽

Ongoing Study ◽

Swiss National Science Foundation ◽

Visual Appearance ◽

Salivary Melatonin ◽

Subjective Alertness ◽

Psychomotor Vigilance ◽

Circadian Physiology

Abstract Introduction Light emitted from visual displays can acutely increase alertness, improve cognitive performance and suppress melatonin in the evening. Here we tested the influence of different melanopic irradiance levels emitted by a metameric display setting on alertness, vigilance and salivary melatonin levels. Methods In an ongoing study, 37 healthy, male participants have so far completed a 2-week study protocol. Volunteers were assigned to one of four luminance groups which differed in brightness levels (27 cd/m2 - 280 cd/m2). Illuminance ranged between 7 and 85 lx. Within the four groups each volunteer was exposed to a low melanopic (LM) and a high melanopic condition (HM). The LM and HM differed in melanopic irradiance (ca. 3-fold change), but matched in terms of cone excitation (metamers). Before, during and after the light exposure, volunteers performed a psychomotor vigilance task (PVT). Subjective alertness and melatonin levels were continuously measured in half-hourly intervals throughout scheduled wakefulness in the 17-h in lab study. Results Preliminary analysis yielded an overall alerting response in the HM vs. the LM condition (p<0.05) concomitant with a trend of reduced melatonin levels in HM vs. LM (p=0.08). So far, we could not observe a difference in PVT performance for HM and LM (Reaction time responses between 100 and 500 ms). Since we are still lacking statistical power in the ongoing study, we cannot yet satisfactorily interpret interaction effects between melanopic condition and brightness. Conclusion Our data indicate that rather low brightness levels of high melanopic display light impacts alertness and melatonin levels in the evening. Thus, metameric low melanopic display light may be a promising method to attenuate activating properties of evening light on circadian physiology without affecting visual appearance. Support (if any) This project is funded by the Swiss National Science Foundation (SNSF).

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An Investigation of the Physical and Electrical Properties of Knitted Electrodes When Subjected to Multi-Axial Compression and Abrasion

Proceedings ◽

10.3390/proceedings2021068002 ◽

2021 ◽

Vol 68 (1) ◽

pp. 2

Author(s):

Arash M. Shahidi ◽

Theodore Hughes-Riley ◽

Carlos Oliveira ◽

Tilak Dias

Keyword(s):

Heart Rate ◽

Electrical Properties ◽

Applied Load ◽

Pressure Sensors ◽

Electrical Performance ◽

Electronic Textiles ◽

Heart Rate Monitors ◽

Mechanical Loads ◽

And Performance ◽

Over Time

Knitted electrodes are a key component to many electronic textiles including sensing devices, such as pressure sensors and heart rate monitors; therefore, it is essential to assess the electrical performance of these knitted electrodes under different mechanical loads to understand their performance during use. The electrical properties of the electrodes could change while deforming, due to an applied load, which could occur in the uniaxial direction (while stretched) or multiaxial direction (while compressed). The properties and performance of the electrodes could also change over time when rubbed against another surface due to the frictional force and generated heat. This work investigates the behavior of a knitted electrode under different loading conditions and after multiple abrasion cycles.

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Artificial complementary chromatic acclimation gene expression system in Escherichia coli

Microbial Cell Factories ◽

10.1186/s12934-021-01621-3 ◽

2021 ◽

Vol 20 (1) ◽

Author(s):

Dwi Ariyanti ◽

Kazunori Ikebukuro ◽

Koji Sode

Keyword(s):

Gene Expression ◽

Escherichia Coli ◽

Light Exposure ◽

Expression System ◽

Red Light ◽

Green Light ◽

Light Illumination ◽

Multiple Gene ◽

Gene Expression System ◽

Chromatic Acclimation

Abstract Background The development of multiple gene expression systems, especially those based on the physical signals, such as multiple color light irradiations, is challenging. Complementary chromatic acclimation (CCA), a photoreversible process that facilitates the control of cellular expression using light of different wavelengths in cyanobacteria, is one example. In this study, an artificial CCA systems, inspired by type III CCA light-regulated gene expression, was designed by employing a single photosensor system, the CcaS/CcaR green light gene expression system derived from Synechocystis sp. PCC6803, combined with G-box (the regulator recognized by activated CcaR), the cognate cpcG2 promoter, and the constitutively transcribed promoter, the PtrcΔLacO promoter. Results One G-box was inserted upstream of the cpcG2 promoter and a reporter gene, the rfp gene (green light-induced gene expression), and the other G-box was inserted between the PtrcΔLacO promoter and a reporter gene, the bfp gene (red light-induced gene expression). The Escherichia coli transformants with plasmid-encoded genes were evaluated at the transcriptional and translational levels under red or green light illumination. Under green light illumination, the transcription and translation of the rfp gene were observed, whereas the expression of the bfp gene was repressed. Under red light illumination, the transcription and translation of the bfp gene were observed, whereas the expression of the rfp gene was repressed. During the red and green light exposure cycles at every 6 h, BFP expression increased under red light exposure while RFP expression was repressed, and RFP expression increased under green light exposure while BFP expression was repressed. Conclusion An artificial CCA system was developed to realize a multiple gene expression system, which was regulated by two colors, red and green lights, using a single photosensor system, the CcaS/CcaR system derived from Synechocystis sp. PCC6803, in E. coli. The artificial CCA system functioned repeatedly during red and green light exposure cycles. These results demonstrate the potential application of this CCA gene expression system for the production of multiple metabolites in a variety of microorganisms, such as cyanobacteria.

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