Article

Lamond N, Dawson D. Quantifying the performance impairment associated with fatigue. J Sleep Res 8: 255-262

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Abstract

The present study systematically compared the effects of fatigue and alcohol intoxication on a range of neurobehavioural tasks. By doing so, it was possible to quantify the performance impairment associated with fatigue and express it as a blood alcohol impairment equivalent. Twenty-two healthy subjects aged 19-26 years participated in three counterbalanced conditions. In the sustained wakefulness condition, subjects were kept awake for 28 h. In the alcohol and placebo conditions, subjects consumed either an alcoholic or non-alcoholic beverage at 30 min intervals, until their blood alcohol concentration reached 0.10%. In each session, performance was measured at hourly intervals using four tasks from a standardised computer-based test battery. Analysis indicated that the placebo beverage did not significantly effect mean relative performance. In contrast, as blood alcohol concentration increased performance on all the tasks, except for one, significantly decreased. Similarly, as hours of wakefulness increased performance levels for four of the six parameters significantly decreased. More importantly, equating the performance impairment in the two conditions indicated that, depending on the task measured, approximately 20-25 h of wakefulness produced performance decrements equivalent to those observed at a blood alcohol concentration (BAC) of 0.10%. Overall, these results suggest that moderate levels of fatigue produce performance equivalent to or greater than those observed at levels of alcohol intoxication deemed unacceptable when driving, working and/or operating dangerous equipment.

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... This has typically been done through hours of service (HOS) regulations [57,58]. While there is evidence that HOS regulations are helpful for managing fatigue, there is less evidence that they are sufficient [57,59]. ...
... We also found that by the end of their night shift non-nappers had been awake for an average of 19h, which puts them in a zone that has been identified in the literature as producing performance impairment equivalent to having a blood alcohol concentration of 0.05-0.10% [59,60]. This is of potential concern for those who are driving home from night shift. ...
... The drive home following night shift is a danger zone for shift workers because they have often been awake for approximately 24 hours by the end of the night shift, which is equivalent to having a blood alcohol concentration above the legal limit for driving [59,60]. Winding down the car windows, playing loud music and chewing ice or sipping on drinks are countermeasures that individuals often assume can help improve their alertness when driving home following a night shift. ...
... Decades of research on human sleep deprivation have resulted in the view that the extent to which a given cognitive task reveals changes during sleep deprivation depends upon such task parameters as duration (5)(6)(7), complexity (8,9), response rate (10), and interest (5,8,11,12). As such, findings regarding the type and magnitude of performance impairment during sleep deprivation are, to a large extent, contingent as much on these task parameters as on any particular type of cognitive test. ...
... Experimental comparisons between the performance effects of alcohol intoxication and sleep deprivation have found quantitative and qualitative similarities for numerous performance parameters including unpredictable tracking (9,99), vigilance (100), and response latency in a logical reasoning task (9). These studies have suggested that after 17-18 hr of sleep deprivation, performance is equivalent to (or greater than) that of a person with a blood alcohol concentration (BAC) of 0.05% (the legal driving limit in Australia) (100), and that after 20-25 hr awake, performance impairment is equivalent to (or greater than) a BAC of 0.10% (the legal driving limit in many states in the United States) (9). ...
... Experimental comparisons between the performance effects of alcohol intoxication and sleep deprivation have found quantitative and qualitative similarities for numerous performance parameters including unpredictable tracking (9,99), vigilance (100), and response latency in a logical reasoning task (9). These studies have suggested that after 17-18 hr of sleep deprivation, performance is equivalent to (or greater than) that of a person with a blood alcohol concentration (BAC) of 0.05% (the legal driving limit in Australia) (100), and that after 20-25 hr awake, performance impairment is equivalent to (or greater than) a BAC of 0.10% (the legal driving limit in many states in the United States) (9). ...
... Although many researchers and car companies have developed systems to predict and prevent sleepiness, these systems only react to a binary or ternary number of levels of sleepiness (Lal et al., 2003;Sayed & Eskandarian, 2001;Yeo et al., 2009;Shuyan & Gangtie, 2009;Patel et al., 2011;NapZapper, 2016;Bosch, 2012;Lexus, 2012), i.e. the sleepiness level changes from "awake" to "sleep" in a binary system and from "awake" to "drowsy" to "sleep" in a ternary system. During the "sleep" level, the driver's capabilities reduce and the probability of a road accident is high (Royal, 2003;Philip & Akerstedt, 2006;Connor et al., 2001;Klauer et al., 2006;Lamond & Dawson, 1999). This means that when a system that can only determine binary states of sleepiness predicts a "sleep" state, the driver is already in a high risk of being involved in a road accident. ...
... The risk of having an accident while being sleepy is four to six times higher than when the driver is alert (Klauer et al., 2006). Researchers have demonstrated that a driver who has sleep deprivation has the same driving skills as a person with an illegal high concentration of alcohol in their system (0.1 g/l) (Lamond & Dawson, 1999). In order to understand how we might build interventions to address this important topic of research, it is necessary first to examine the physiology of sleep and distinguish the difference between alertness and sleepiness as well as the different "sleep" and "awake" stages before engaging in methods to predict and prevent people from falling asleep while driving. ...
... The stage prior falling asleep is called drowsiness (Johns, 2000). This state can be recognized by difficulty in maintaining visual focus attention, limitation of the higher cognitive functions, and limitations in the visual perception (Lamond & Dawson, 1999;Thomas et al., 1998). This level is also characterized by the appearance of microsleeps (Broughton & Hasan, 1995;Tanaka, Hayashi, & Hori, 1996) as well as increase in the alpha and theta activity in the brain and a decrease in the beta activity in the brain (Jap et al., 2009;Lal & Craig, 2001a,b;Stern & Engel, 2005;Yeo et al., 2009;Zhao et al., 2012;Akerstedt & Gillberg, 1990;Campagne, Pebayle & Muzet, 2004;Jap et al., 2009;Kecklund & Akerstedt, 1993;Lowden et al., 2009). ...
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Thesis
This research investigates the use of objective EEG analysis to determine multiple levels of sleepiness in drivers. In the literature, current methods propose a binary (awake or sleep) or ternary (awake, drowsy or sleep) classification of sleepiness. Having few classification of sleepiness increases the risk of the driver reaching dangerous levels of sleepiness before a safety system can prevent it. Also, these methods are based on subjective analysis of physiological variables, which leads to lack of reproducibility and loss of data, when a lack of consensus is reached amongst the EEG experts. Therefore, the doctoral challenge was to determine whether multiple levels of sleepiness could be defined with high accuracy, using an objective analysis of EEG, a reliable indicator of sleepiness. The study identified awake, post-awake, pre-sleep and sleep as the multiple levels of sleepiness through the objective analysis of EEG. The research used Neural Networks, a type of Machine Learning algorithm, to determine the accuracy of the proposed multiple levels of sleepiness. The Neural Networks were trained using driving and physiological behaviour. The EEG data and the driving and physiological variables were obtained through a series of experiments aimed to induce sleepiness, conducted in the driving simulator at the University of Leeds. As the Neural Network obtained high accuracy when differentiating between awake and sleep and between post-awake and pre-sleep, it led to the conclusion that the proposed objective classification based on objective EEG analysis was suitable. However, this study did not reach the highest levels of accuracy when the 4 levels of sleepiness are combined, nevertheless the solutions proposed by the researcher to be carried in future work can contribute towards increasing the accuracy of the proposed method.
... The 12-h shift work, typical of FIFO work, leads to fatigue, which negatively affects productivity [29]. Fatigue can impair performance to levels equivalent to alcohol intoxication [30] and exposes workers to a higher risk of accidents and injury [31,32]. Reducing fatigue and associated health and safety risks will require input from both FIFO organizations and workers themselves. ...
... Twelve-hour shift work, which is typical for FIFO work, leads to fatigue, which negatively affects productivity [29]. Fatigue can impair performance to levels equivalent to alcohol intoxication [30] and exposes workers to a higher risk of accidents and injury [31,32]. ...
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Article
With high health requirements for FIFO work at industry, workers may experience adverse changes in psychological well-being and health status. This makes it relevant when developing the job performance model to rely on considering not only the effectiveness by employees but also their psychophysiological “cost of activity”, which is not reflected in modern scientific research. This article theoretically substantiates and empirically develops a job performance typology of fly-in-fly-out workers at industrial enterprises by correlating three components: effectiveness, psychophysiological resources, and the way of accomplishing tasks. The study involved 359 fly-in-fly-out workers in oil and gas, diamond mining and construction industries with different duration of the fly-in period, operating in the South and the North of the Russian Federation. The research methods included questioning, psychophysiological instrumental testing, and psychological testing. Statistical processing was carried out using the methods of descriptive statistics, two-stage cluster analysis, and multivariate analysis of variance. As a result of the study, six types of job performance of fly-in-fly-out personnel of industrial enterprises were identified. The employees at industrial enterprises of all six types of job performance correspond to their position and perform the assigned tasks, the difference in them lies in the desire to show an average or the highest possible result, as well as how much internal resources the employee spends to achieve this result and how quickly he restores them, which is expressed in terms of his state and well-being. Based on the results of these connections, measures for personnel management for industrial enterprises were proposed.
... They found that fatigue from sleep (24 hours of sustained wakefulness) had a greater impact on the speed of continuous attention, memory, and learning and the accuracy of complex matching than alcohol. These findings were in line with those of Lamond & Dawson (1999) [158], who found that exhausted drivers (those who had been awake for more than 22 hours) had a slower rate of continuous attention than those with a BAC of less than 0.05 percent. ...
... They found that fatigue from sleep (24 hours of sustained wakefulness) had a greater impact on the speed of continuous attention, memory, and learning and the accuracy of complex matching than alcohol. These findings were in line with those of Lamond & Dawson (1999) [158], who found that exhausted drivers (those who had been awake for more than 22 hours) had a slower rate of continuous attention than those with a BAC of less than 0.05 percent. ...
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Article
The number of traffic accidents because of distracted driving is increasing rapidly worldwide. Hence, the main objective of the present study is to review the effects of different distracting factors on driving performance indicators. Distracting factors considered in this study are roadside advertisements (billboards), mobile use, in-built vehicle systems, and sleepiness; and driving performance indicators are lane deviation, reaction time, and speed variation. Studies from existing literature reveal that all the distracting factors distract drivers from forwarding roadways in many ways. The location and content displayed on the billboard and the use of mobile phones increase reaction time. However, the former decreases the driver’s ability to control the vehicle, and the latter increases the speed variation and reduces lane-keeping capacity. Lateral vehicle control and reaction time are compromised when drivers engage in searching for songs or videos on music players. When sleepiness occurs, drivers exhibit a higher standard deviation of speed and a decreased headway distance. Nevertheless, most of the studies in this area are carried out in developed countries like the USA and European countries. Therefore, a detailed study and further research in developing countries like India, where activities like installing billboards and mobile phone use are increasing day by day due to the rapid urbanization of major cities in the country, are quite essential. Doi: 10.28991/CEJ-2022-08-02-014 Full Text: PDF
... Research on younger adults shows that birthday celebrations are associated with significantly higher levels of blood alcohol concentration compared to public holidays or special days, such as graduation (Neighbors et al. 2011). In particular alcohol consumption is associated with poorer sleep quality and quantity (Singleton and Wolfson 2009), resulting in fatigue on the next day (Lamond and Dawson 1999). Metabolic fatigue involves feelings of tiredness and low energy levels which negatively affect physical performance (Lamond and Dawson 1999), especially running performance (Bangsbo, Iaia, and Krustrup 2007). ...
... In particular alcohol consumption is associated with poorer sleep quality and quantity (Singleton and Wolfson 2009), resulting in fatigue on the next day (Lamond and Dawson 1999). Metabolic fatigue involves feelings of tiredness and low energy levels which negatively affect physical performance (Lamond and Dawson 1999), especially running performance (Bangsbo, Iaia, and Krustrup 2007). Consequently, running performance is expected to be significantly worse on the day following an individual's birthday. ...
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While the birthday effect has been widely studied in the economics and sport literature, this study introduces the concept of the ‘real’ birthday effect. It holds that birthday celebrations yield fatigue, which negatively affect running performance. The purpose of this study is to examine the effect of players’ birthdays on post-birthday running performance using data from the German Football Bundesliga (2011–2018). The dataset includes 1,040 different field players who played in 2,142 matches (n= 49,233). Running performance was measured by the total distance covered during the game (in m per minute) and the number of intensive runs (>20 and <24 km/h; per minute). On average, players ran 123.68 m and performed 0.70 intensive runs per minute, which are equivalent to 11.1 km and 63 intensive runs during a 90-minute match. The results of fixed effects panel regression analyses, which also control for various player, game, and team characteristics, show that players perform significantly fewer intensive runs on the day following their birthday. This finding supports the concept of the ‘real’ birthday effect. Football coaches should reconsider fielding players on match days succeeding their birthday as these players perform significantly fewer intensive runs.
... Interestingly, several studies have sought to understand the shortterm effects of extended wakefulness using the framework of blood alcohol concentration (BAC). 39,40 A BAC greater than 0.05% is widely accepted as hazardous. 41 Impairments in cognitive performance after extended wakefulness of 17-19 h has been shown equivalent to a BAC of 0.05% 39 and after 20-25 h equivalent to BAC of 0.10%. ...
... 41 Impairments in cognitive performance after extended wakefulness of 17-19 h has been shown equivalent to a BAC of 0.05% 39 and after 20-25 h equivalent to BAC of 0.10%. 39,40 This study found that 55% of hospitals utilizing a traditional structure rostered registrars to week-day on-call of >20 h duration, compared with 14% of those with hybrid or ASU models. These rosters are likely to lead to diminished cognitive performance in these clinicians. ...
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Background: Few studies have assessed the relationship between different emergency general surgery models and staff satisfaction, operative experience or working hours. The Royal Australasian College of Surgeons recommends maximum on-call frequency of one-in-four for surgeons and registrars. Methods: A cross-sectional study was conducted of all medium- to major-sized Australian public hospitals offering elective general surgery. At each site, an on-call general surgery registrar and senior surgeon were invited to participate. Primary outcomes were staff satisfaction and registrar-perceived operative exposure. Secondary outcomes were working hours. Results: Among eligible hospitals, 119/120 (99%) were enrolled. Compared with traditional emergency general surgery models, hybrid or acute surgical unit models were associated with greater surgeon and registrar satisfaction on quantitative (P = 0.012) and qualitative measures. Registrar-perceived operating exposure was unaffected by emergency general surgery model. Longest duration on-duty was higher among traditional structures for both registrars (mean 22 versus 15 h; P = 0.0003) and surgeons (mean 59 versus 41 h; P = 0.020). On-call frequency greater than one-in-four was more common in traditional structures for registrars (51% versus 28%; P = 0.012) but not surgeons (6% versus 0%; P = 0.089). Data on average hours per day off-duty were obtained for registrars only, and were lower in traditional structures (13 versus 15 h; P = 0.00002). Conclusion: Hybrid or acute surgical unit models may improve staff satisfaction without sacrificing perceived operative exposure. While average maximum duration on-duty exceeded hazardous thresholds for surgeons regardless of model, unsafe working hours for registrars were more common in traditional structures. General surgical departments should review on-call rostering to optimize staff and patient safety.
... Estudos nacionais e estrangeiros apresentam a fadiga, sonolência, cansaço físico e mental, uso de drogas e pagamento por produção entre os principais fatores que levam a acidentes no trabalho com motoristas profissionais. Apesar disso, o TRC tem se organizado de forma a privilegiar a produtividade, geralmente atrelando a remuneração dos motoristas ao número e extensão das viagens, o que os leva a cumprir longas jornadas com pouco descanso, uma combinação considerada como um dos principais fatores que contribuem para a ocorrência de acidentes [6][7][8][9][10][11][12][13][14][15] . ...
... Arnedt et al.11 , assim como Lamond e Dawson12 , conduziram estudos que mostraram que a queda de desempenho na execução de atividades como dirigir 17-19 horas e 20-25 horas sem dormir é similar a dirigir com concentração de álcool no sangue de 0,05% e 0,10% (0,10 gramas de etanol por 100 ml de sangue), respectivamente. Segundo o International Center for Alcohol Policies 30 , a concentração de 0,10%, é o dobro do limite legal da maioria dos países. ...
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Resumo Introdução: um grande número de acidentes de trabalho fatais (ATF) ocorre no Transporte Rodoviário de Cargas (TRC). Jornada de trabalho excessiva e descanso inadequado dos motoristas são apontados entre os principais fatores contribuintes. É atribuição do Ministério do Trabalho fiscalizar essas condições. Objetivos: avaliar se a ação da fiscalização do trabalho no setor de TRC recebeu atenção proporcional à magnitude dos indicadores de mortalidade por acidente de trabalho nessa atividade e analisar a inclusão dos fatores jornada e descanso nas inspeções. Métodos: estudo exploratório, quantitativo, descritivo, com base documental e bibliográfica e utilização de dados oficiais de ATF e da Fiscalização do Trabalho, de 2008 a 2012. Resultados: entre as 20 atividades/ocupações com mais mortes, o TRC (1430 óbitos; 37,97 mortes/100 mil vínculos) e a ocupação de motorista de caminhão de longas distâncias (1098 óbitos; 55,33 mortes/100 mil vínculos, em 2011) se destacaram. Contudo, as ações de fiscalização no setor representaram 1,4% do total no período investigado e a inclusão da jornada e descanso dos motoristas se deu somente em metade dessas ações. Conclusão: é necessário incremento no número de fiscalizações no TRC e na abordagem dos fatores contribuintes para os ATF dos motoristas de caminhão.
... Studies using laboratory-based measures of attention and reaction time have found that participants kept awake for prolonged periods of time experience longer and more frequent lapses in attention [7]. Studies comparing the effects of sustained wakefulness and alcohol consumption on tasks including reaction time, hand-eye coordination, and simulated driving performance have found similar performance decrements associated with both [8][9][10]. Case-control studies have compared binary measures of acute sleep deprivation (e.g. ...
... The current study's ORs for culpable crash involvement associated with 5, 4, and less than 4 hr of sleep were similar to ORs estimated in that study for drivers with BACs of 0.03, 0.05, and 0.12, respectively [18]. This similarity of the effects of sleep deprivation estimated herein and the effects of alcohol estimated in previous studies [18,37] is broadly consistent with the results of laboratory-based studies that have compared the effects of these two risk factors within the same experiment [8][9][10]. ...
Article
Study Objectives To quantify the relationship between acute sleep deprivation and culpable involvement in motor vehicle crashes. Methods Participants were 6845 drivers involved in a representative sample of crashes investigated by the US Department of Transportation in years 2005–2007. A modified case–control study design was used to compare self-reported hours of sleep in the 24 hr before crashing between drivers deemed culpable versus nonculpable. Analyses controlled for fatigue-related, driver-related, and environmental factors. Specific errors that led to crashes were also examined. Results Drivers who reported having slept for 6, 5, 4, and less than 4 hr in the 24 hr before crashing had 1.3 (95% confidence interval [CI] = 1.04 to 1.7), 1.9 (1.1 to 3.2), 2.9 (1.4 to 6.2), and 15.1 (4.2 to 54.4) times the odds, respectively, of having been culpable for their crashes, compared with drivers who reported 7–9 hr of sleep. Drivers who had slept less than 4 hr had 3.4 (95% CI = 2.1 to 5.6) times the increase in odds of culpable involvement in single-vehicle crashes compared with multiple-vehicle crashes. Recent change in sleep schedule, typically feeling drowsy upon waking, and driving for 3+ hr were also associated with culpability (all p ≤ 0.013). Assuming nonculpable drivers comprised a representative sample of all drivers present where crashes occurred, these odds ratios approximate incidence rate ratios for culpable crash involvement per unit of time driving. Conclusions Driving after having slept less than 7 hr in a 24 hr period is associated with elevated risk of culpable crash involvement. Risk is greatest for drivers who have slept less than 4 hr and is manifested disproportionately in single-vehicle crashes.
... Not performing this activity decreases the ability to react and pay attention even to perform tasks as simple as sending an email. Studies [1], [ 2], [3] show that going too long without sleep can impair driving ability to the same extent as drinking alcohol in excess. "Being awake for at least 18 hours is equivalent to having a BAC of 0.05 percent" [4]. ...
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Conference Paper
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... Performance on all driving measures were significantly worse with sleep deprivation and in the early morning, consistent with previous research [4,[40][41][42]. Time on task, as a workload factor, also impacted driving performance as demonstrated by the significant increase in lane deviation from loop 1 to loop 2. In fact, there were performance decrements from 15-min into the driving task, specifically at 01:00. ...
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... Being awake for at least 24 hours is equal to having a blood alcohol content of 0.10%. This is higher than the legal limit (0.08% BAC) in all states [11] and [25]. As a fatigue detection device, BCI could be of great significance in the prevention of driving fatigue. ...
... An analogy used to describe the impairment created by fatigue is comparing its effect to that of alcohol. Being awake for 20-25 hours leads to the same degree of impairment as having a blood alcohol concentration of 0.10% (Dawson & Reid, 1997;Lamond & Dawson, 1999). This level of intoxication would be deemed as unacceptable for driving or operating machinery. ...
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Book
A guide to non-technical skills in emergency management by Dr Peter Hayes, A/Prof Chris Bearman and Donald Gyles is the first book of its kind for emergency management. It was developed as observations from the authors indicated the need to better manage non-technical skills during emergency and incident management; non-technical skills continue to be an area highlighted in investigation reports and inquiries; and discussions with agency partners indicated a a resource like this book would help to educate practitioners deepen their understanding of the non-technical skills literature. What is in the book? A guide to non-technical skills in emergency management seeks to: introduce and highlight the importance of non-technical skills; identify some of the issues and pitfalls that can occur; and describe tools that can help people better manage non-technical skills in operational situations. The content of the book necessarily draws heavily on research conducted during by the Improving decision-making in complex multi-team environments project conducted between 2014–2021. By writing this book the authors hope to provide a consistent framework that allows agencies to manage the various aspects of non-technical skills in a more holistic way. This also encourages agencies to adopt a shared language to discuss, promote and manage these important but often neglected sets of skills. Who is the book for? The book is designed for emergency management practitioners and instructors who wish to understand more about non-technical skills. This may be because they want to improve their own knowledge and practice or be better prepared to coach, mentor or instruct others. Learning and development practitioners may find the book a useful reference source for developing non-technical skills training materials or for enhancing these skills within more technically oriented training units (for example, teaching communication skills in the context of relay pumping). The approach Some readers will be familiar with these skills and will have used them working in various teams. For others, it may be the first time they have encountered them. For the group who are encountering non-technical skills for the first time, the authors have provided a simple overview of each skill and how it can be observed in both training and real operations. For the more experienced practitioners of non-technical skills the authors have included a set of information and challenges to help people to think more deeply about that non-technical skill. + Chapter 1 introduces the concept of non-technical skills and demonstrates how non-technical skills can be operationalised. + Chapters 2 through 8 are the central part of the book and use the Emergency Management Non-Technical Skills (EMNoTS) framework as the basis for discussion of the seven key non-technical skills critical to effective emergency and incident management. + These non-technical skills are: communication, coordination, cooperation, situation awareness, decision making, leadership and managing stress and fatigue. + Each of these non-technical skills is discussed in a separate chapter, with each chapter introducing the non-technical skill and identifying behavioural markers that can be used to observe the skill in action. For readers wanting more detail this is followed by a ‘More information’ section and a section that discusses some of the challenges that may be encountered. + Each chapter also offers suggested readings and links to relevant online resources, in addition to the many references. + Chapter 9 highlights how to use a non-technical skills framework to manage performance. + The final chapter (Chapter 10) identifies implications and opportunities for the management of the non-technical skills.
... Exceeding 10 night shifts in a 30day time interval causes an average maximum equivalent time awake higher than 24 hours, or, equivalently, an average maximum sleep deficit of more than 8 hours. Indeed, Lamond and Dawson have found [34] that 20-25 hours of continuous wakefulness can be associated with decrements in performance scores related with reasoning and attention, and that these degradations could be comparable for individuals with a blood alcohol concentration of 0.10 %. The adverse effects of long periods of wakefulness were also pointed as a probable cause for aviation accidents. ...
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Preprint
This work evaluates the potential root causes of fatigue using a biomathematical model and a robust sample of aircrew rosters from the Brazilian regular aviation. The fatigue outcomes derive from the software Sleep, Activity, Fatigue, and Task Effectiveness Fatigue Avoidance Scheduling Tool (SAFTE-FAST). The average minimum SAFTE-FAST effectiveness during critical phases of flight decreases cubically with the number of shifts that elapse totally or partially between mid-night and 6 a.m. within a 30-day period ($N_{NS}$). As a consequence, the relative fatigue risk increases by 23.3% (95% CI, 20.4-26.2%) when increasing $N_{NS}$ from 1 to 13. The average maximum equivalent wakefulness in critical phases also increases cubically with the number of night shifts and exceeds 24 hours for rosters with $N_{NS}$ above 10. The average fatigue hazard area in critical phases of flight varies quadratically with the number of departures and landings within 2 and 6 a.m. ($N_{Wocl}$). These findings demonstrate that both $N_{NS}$ and $ N_{Wocl}$ should be considered as key performance indicators and be kept as low as reasonably practical when building aircrew rosters. The effectiveness scores at 30 minute time intervals allowed a model estimate for the relative fatigue risk as a function of the time of the day, whose averaged values show reasonable qualitative agreement with previous measurements of pilot errors. Tailored analyses of the SAFTE-FAST inputs for afternoon naps before night shifts, commuting from home to station and vice-versa, and bedtime before early-start shifts show relevant group effects ($p < 0.001$) comparing the groups with and without afternoon naps, with one or two hours of commuting and with or without the advanced bedtime feature of the SAFTE-FAST software, evidencing the need of a better and more accurate understanding of these parameters when modelling fatigue risk factors.
... The term drowsiness, often used interchangeably with the terms fatigue and sleepiness in the literature, relates to a physiological need to sleep, as it is the intermediate state between wakefulness and sleep [85]. This state comes with the impairment of visual perception, of higher cognitive functions, the inability to maintain visually focused attention, among other undesirable consequences for safe driving [86]. ...
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As technology and artificial intelligence conquer a place under the spotlight in the automotive world, driver drowsiness monitoring systems have sparked much interest as a way to increase safety and avoid sleepiness-related accidents. Such technologies, however, stumble upon the observation that each driver presents a distinct set of behavioral and physiological manifestations of drowsiness, thus rendering its objective assessment a non-trivial process. The AUTOMOTIVE project studied the application of signal processing and machine learning techniques for driver-specific drowsiness detection in smart vehicles, enabled by immersive driving simulators. More broadly, comprehensive research on biometrics using the electrocardiogram (ECG) and face enables the continuous learning of subject-specific models of drowsiness for more efficient monitoring. This paper aims to offer a holistic but comprehensive view of the research and development work conducted for the AUTOMOTIVE project across the various addressed topics and how it ultimately brings us closer to the target of improved driver drowsiness monitoring.
... According to Davis [50], welltrained individuals periodically make mistakes, accept an occasional blunder, or modify assigned tasks to minimize unwanted incidences such as collapse. Lamond and Dawson [51] claimed that fatigue could result in a performance impediment that is equivalent to or higher than 0.1 percent of Blood Alcohol Concentration (BAC). This level is deemed unsafe for driving a crane or operating hazardous gear. ...
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This study addresses how employee well-being and knowledge sharing behaviour can be managed within challenging work factors in the workplace environment. Besides identifying antecedents to well-being, it also seeks to examine the impact of well-being (psychological, physical, and social) on knowledge sharing behaviour (tacit and explicit). The methodology of research in the present study is quantitative. The survey technique was used in data collection, it was conducted among 362 Saudi Aramco employees using the judgmental sampling method. Smart PLS was used for analyzing data. The findings illustrated that 1. Job hazards were found to affect the physical well-being of employees significantly. 2. As a result of improvement in physical and social well-being, better knowledge-sharing behaviour in both tacit and explicit dimensions was demonstrated. In specific, tacit knowledge-sharing behaviour is motivated more by physical well-being while explicit knowledge-sharing behaviour is by social well-being. 3. Workplace conflict is found positively related to social well-being, contradicting hypothesized relationships. This seems to indicate Saudi Aramco employees embrace differences in view, beliefs, and feelings at work, and open discussion of conflicts enhances their social well-being. This study provides ideas to human resource management on strategies to enhance employee well-being for improved knowledge sharing behavior. Also, managers are encouraged to use open debates of differing views to resolve work matters professionally. This study deviates from current employee well-being studies by recognizing three different types of employees well beings (psychological, physical, and social) that contribute differently to knowledge sharing behavior. Also, it identifies factors that determine employee well beings. INTRODUCTION Owing to changes in the domestic and global economy, increased competition, and the rapid rate of technological change, more organizations in the 21st century, are giving employee well-being more prominence. Many research studies on employee well-being have been explored in recent decades by multiple researchers based on their various motives, recognitions, and points of view. Maslow's hierarchy of needs (1970)[See. 1], DeNeve and Cooper's goal-directed behaviour (1998)[See. 2], and Heady and Wearing's dynamic equilibrium model are among them (1989)[See. 3]. Several researchers attempted to clarify the concepts behind employees' well-being and its outcomes [4-9]. Moreover, many concepts suggested by experts were different, and all of them appear to conceptualize and understand employees' well-being and the challenging work factors. According to the concept of organizational behaviour, this research reinforces Maslow's theoretical concept, organizational culture, and well-being to create an integrative understanding of the challenging work factors that could affect individuals' information sharing behaviour in a sophisticated organizational environment like Aramco.
... 18 Sleep has been proposed to have a bidirectional interaction with cognitive function in traumatized people. [19][20][21][22] However, whether the sleep-attention relationship is enhanced or weakened in traumatized refugees is unclear. Furthermore, since both sleep and attention are strongly affected by depression, anxiety, and other trauma-related symptoms that are very common in refugees, 23,24 these factors should be considered when investigating the association between attention and sleep in traumatized refugees. ...
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Introduction: Attentional deficits and sleep problems are common in refugees who have experienced trauma. In the present study, we used polysomnography (PSG) to investigate the relationship between attentional deficits and objective measures of sleep structure in traumatized North Korean refugees. Methods: We recruited 32 North Korean refugees (mean age = 33.78 ± 14.33 years) and 39 South Korean participants (mean age = 35.03 ± 11.08 years). Sustained attention and divided attention were assessed using the Computerized Attention Test. We conducted an overnight PSG to objectively assess sleep structure. The participants also completed the Beck Depression Inventory (BDI), Beck Anxiety Inventory (BAI), Impact of Event Scale-Revised (IES-R), Epworth Sleepiness Scale (ESS), Pittsburgh Sleep Quality Index (PSQI), and Insomnia Severity Index (ISI). Results: The North Korean refugees showed more commission errors (CEs, p < 0.05) and a larger standard deviation (SD) of the reaction time (RT) (p < 0.05) in the sustained attention task compared to the South Korean participants. Furthermore, the North Korean refugees showed a shorter period of wake after sleep onset (WASO, p < 0.01), less time spent in N1 (p < 0.05), and more time spent in N2 (p < 0.05). The larger SD of RT in the sustained attention task in the North Korean refugees was positively correlated with WASO (r = 0.62, p < 0.01) and N1 stage (r = 0.47, p < 0.05) after controlling for age, sex, BDI, BAI, and IES-R. Conclusion: The North Korean refugees showed poorer performance on the sustained attention task. Nocturnal PSG revealed shorter WASO and time spent in N1 in this population, which are independently associated with the preservation of attentional capacity. These data suggest that traumatized refugees may compensate for attentional deficits induced by their traumatic experiences via increased sleep continuity.
... The cognitive/psychomotor performance decrements caused by a certain degree of sleep deprivation/fatigue have been equated to alcohol intoxication at various blood alcohol levels in past studies. [10][11][12] We refer to fatigue levels that are equivalent to certain thresholds of blood alcohol content (BAC) in the results to associate the level of impairment to an identifiable marker. During the trial evaluating the original submarine watch system (1-in-2, 6-on and 6-off, for the tactical submariners and a rotating 1-in-3 for the engineering submariners), modeled cognitive effectiveness was very worrisome for both watch systems. ...
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Introduction: Life on board a naval vessel is exceptionally demanding. Workdays for naval sailors can quite easily become 18+ hours long when watch schedules, training, and drills/evolutions are taken into account. Rotating watches and short off-watch periods can force sailors into a biphasic sleep pattern that is not sufficiently restful or a rotating pattern that is impossible to adapt to. Materials and methods: Six different watch systems were evaluated over four separate at-sea trials. Engineering and tactical/combat departments have had different watch systems in the past because of constraints related to the specific environment in which they work. Therefore, two of the watch systems were engineering-specific watch evaluations, three of the systems were specific to tactical/combat departments, and one watch system was evaluated with the entire company of the naval vessel. Results: Both two-section (1-in-2) watch systems and three-section (1-in-3) watch systems were evaluated, which involve two or three shifts of sailors rotating through a full continuous 24-h day, respectively. Moving beyond three rotations of sailors is impossible on Canadian naval vessels due to bunk space and other limitations. The best watch system that we evaluated with respect to fatigue and quality of life at sea was the 1-in-3 straight 8-h shift system that was tested for the entire ships' company. The system has a single 8-h daily watch obligation (red watch, 4:00 am-12:00 pm; white watch 12:00 pm-8:00 pm; and blue watch, 8:00 pm-4:00 am). The best 1-in-2 system was the 8-4-4-8 system in which sailors are on-watch for 8 h, off-watch for 4 h, on-watch for 4 h, and then rest for 8 h. Both of these two systems have the advantage of equitably sharing the Window of Circadian Low (from about midnight to about 8:00 am), especially when melatonin concentration in the body is usually at its peak, between 2:00 am and 6:00 am. Conclusions: The goal of this work was to comprehensively evaluate both submarine and surface fleet watch systems. We were able to develop alternative watch systems that increased Royal Canadian Navy operational readiness and improved the quality of life of our sailors at sea.
... (3) Continuous wakefulness. More than 22 h of wake time is typically considered the point at which fatigue causes almost all aspects of human performance to decline (Lamond and Dawson 2002). Uncontrollable brief "micro-sleeps" and "state instability" -whereby wakefulness cannot be maintained -begin to occur in most individuals at this point (Beaumont et al. 2001). ...
Article
Fatigue that is related to the amount and quality of sleep obtained can impair human performance in ways that can lead to accidents. As many transportation industries operate around the clock, fatigue and its effects cannot be eliminated completely; instead, they must be managed. A first step is to document the prevalence and role of fatigue in accidents that occur. The Transportation Safety Board of Canada (TSB) routinely investigates such transportation industry incidents to determine if fatigue was present, if it played a role, and if there were practices in place to effectively manage it and associated risks. Herein, we summarize and describe the TSB’s fatigue investigation methodology in the hopes that investigators of other organizations and domains will find the concepts applicable to their operational context.
... It is well known that low levels of alertness resulting from sleep-related factors are associated with a reduction in the ability to focus, which, in turn, affects learning and task performance (Chee & Choo, 2004;Lim & Dinges, 2010;Sievertsen et al., 2016). To highlight just one example, performance accuracy in adults on certain basic cognitive and neurobehavioral tasks is more impaired after mild sleep deprivation than after alcohol intake that exceeds the levels for legal intoxication (Lamond & Dawson, 1999). For teenagers, various factors connected to sleep (e.g., sleep time, circadian rhythms, sleep loss) are shown to influence levels of focus, alertness, and mood, both within and outside of laboratory contexts (Goldin et al., 2020;Preckel et al., 2011;Short et al., 2013;. ...
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Researchers, parents, and educators consistently observe a stark mismatch between biologically preferred and socially imposed sleep-wake hours in adolescents, fueling debate about high school start times. We contribute neural evidence to this debate with electroencephalogram (EEG) data collected from high school students during their regular morning, mid-morning and afternoon classes. Overall, student alpha power was lower when class content was taught via videos than through lectures. Students’ resting state alpha brain activity decreased as the day progressed, consistent with adolescents being least attentive early in the morning. During the lessons, students showed consistently worse performance and higher alpha power for early morning classes than for mid-morning classes, while afternoon quiz scores and alpha levels varied. Together, our findings demonstrate that both class activity and class time are reflected in adolescents’ brain states in a real-world setting, and corroborate educational research suggesting that mid-morning may be the best time to learn.
... There are several variables (e.g., sleep time, age, temperature) that can be related to this variability in human factor performance. Sleep deprivation results, for example, in impaired reaction time, lengthy decision making and slow cognitive processing [6][7][8][9][10][11][12]. Thus, it is possible and likely that there are several impacts on the performance of the human factor due to only one variable, such as the lack of adequate sleep. ...
... For sleep deprivation instead, longer naps might be more effective and with more long-lasting benefits (Schweitzer et al., 2006) . Even though, the effects of naps on subjective sleepiness are not clear, reporting (Helmus et al., 1997;Naitoh et al., 1981) or not (Dinges et al., 1988;Dinges et al., 2000) high levels of alertness, it is evident that naps ranging between 15 minutes and 2 hours duration following 36-88 hours of sleep deprivation increase cognitive performance (Dinges et al., 1988;Dinges et al., 2000;Lamond & Dawson, 1999;Perlstein et al, 2001) . Furthermore, naps seem to be more effective if placed during the first part of the sleep deprivation period, before accumulating considerable sleep debt (Dinges et al., 1988;Mullaney et al., 1983) . ...
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Mental fatigue and sleep deprivation are two common conditions in our modern societies, affecting millions of healthy people. Whereas mental fatigue is considered a psychobiological state caused by prolonged and demanding cognitive activities, sleep deprivation can be defined as a brain state caused by at least 24 hours of wakefulness. The first aim of this thesis was to investigate the acute effects of mental fatigue, sleep deprivation and subsequent recovery sleep on endurance exercise performance. The second aim was to evaluate the effects of two innovative training interventions, Brain Endurance Training (BET) and Sleep Deprivation Training (SDT) on endurance performance. It was hypothesized that: 1) 50-min of mentally-demanding cognitive task and 25-h of sleep deprivation would impair endurance performance and that the following night of recovery sleep would be enough to restore rested endurance performance; 2) six weeks of BET (alone) and six weeks of SDT (combined with physical training) would improve endurance performance. The first and second study do not provide reliable evidence that mental fatigue and sleep deprivation reduce endurance performance during a half-marathon and a 20-min cycling time trial, respectively. However, an alternative statistical analysis used in study one, suggests that the hypothesis that mental fatigue is harmful cannot be rejected. The third study shows that BET is not effective in physically-inactive males. The fourth study reveals that SDT in combination with physical training might be beneficial to counteract the effects of sleep deprivation on endurance performance. In conclusion, the findings do not provide statistical evidence of a negative effect of mental fatigue and sleep deprivation on endurance performance. However, it might be prudent to avoid them prior to races. The use of BET alone does not enhance endurance performance. Nonetheless, the combination of SDT with a physical training program might be beneficial in preparation for an endurance/ultra-endurance event. Mental Fatigue and Sleep Deprivation: Effects, Mechanisms, and Countermeasures in Endurance Exercise Performance.
... postural compensation and rating the severity of discomfort). Fatigue, in terms of physical performance, however, is a temporary condition induced by continued activity that can be quantified by using EMG (Lamond and Dawson, 1999;Tucker, 2003;Jari� c et al., 1997). ...
Article
This systematic review aimed to evaluate whether muscle activity and playing-related musculoskeletal disorders are associated with musicians’ anthropometrics and their instrument size or set-up during violin and piano performance. Studies were retrieved systematically from six databases on 1 April 2019 combined with hand searching results. The Appraisal tool for Cross-Sectional Studies (AXIS tool) was used to evaluate the methodological quality of the included papers. A total of twenty articles were identified. Most included studies focussed on either the adjustment of the shoulder rest in violinists, or the hand size in pianists. However, methodological quality was inconsistent. The electromyography data reported by the included studies were not appropriately processed and interpreted. Studies generally reported the use of a shoulder rest changes muscle activity and smaller hand size is correlated to increased playing-related musculoskeletal disorders incidence. However, no conclusions can be drawn due to heterogeneity and low quality of methodology in the available literature.
... Sleep deprivation and circadian disruption can result in poor alertness and reaction time [3]. The decline in cognitive performance after 20 to 25 hours of wakefulness is equivalent to a Blood Alcohol Concentration (BAC) of 0.10% [4]. To compare, in New York State, a BAC of more than 0.05% is considered "impaired" and 0.08% is considered "intoxicated" [5]. ...
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Human biology is deeply rooted in the daily 24-hour temporal period. Our biochemistry varies significantly and idiosyncratically over the course of a day. Staying out of sync with one's circadian rhythm can lead to many complications over time, including a higher likelihood for cardiovascular disease, cancer, obesity, and mental health problems [1]. Constant changes in daily rhythm due to shift work has been shown to increase risk factors for cancer, obesity, and Type 2 diabetes. Moreover, the advent of technology and the resultant always-on ethos can cause rhythm disruption on personal and societal levels for about 70% of the population [2]. Circadian disruption can also cause a serious deficit in cognitive performance. In particular, alertness - a key biological process underlying our cognitive performance - reflects circadian rhythms [3]. Sleep deprivation and circadian disruption can result in poor alertness and reaction time [3]. The decline in cognitive performance after 20 to 25 hours of wakefulness is equivalent to a Blood Alcohol Concentration (BAC) of 0.10% [4]. To compare, in New York State, a BAC of more than 0.05% is considered "impaired" and 0.08% is considered "intoxicated" [5]. In other words, the effects of sustained sleep deprivation and circadian disruption on cognitive performance is similar (or worse) to being intoxicated.
... Je länger die Wachphasen andauern, desto höher ist auch die Beeinträchtigung der Einsatzkräfte. In diesem Zusammenhang wird eine Wachphase von 17 Stunden mit einem Blutalkoholwert von 0,5 Promille, eine von 24 Stunden schon mit 1,0 Promille gleichgesetzt (14). ...
Article
Die Tätigkeit im Rettungsdienst gilt als circadianer Faktor für die Entstehung von Schlafstörungen. Diese sind in allen Altersgruppen vertreten und können langfristig zu gesundheitlichen Beschwerden führen (1, 2). Hierbei gilt besonders die Schichtarbeit als ein Risikofaktor für häufige Schlafstörungen (3). Demzufolge sind arbeitsmedizinische Vorsorgeuntersuchungen und präventive gesundheitsfördernde Konzepte von hoher Bedeutung.
... The sleeplessness lasting for 20 to 28 hours has been revealed to cause an effect equal to 0.10% blood-alcohol rate. In several countries, the legal limit for blood-alcohol rate is accepted to be at 0.05% and 0.08% interval (Lamond and Dawson, 1999). Attention deficits in drivers for every 90 to 120 minutes no matter what their ages and physical conditions. ...
... These findings are consistent with previous studies that reported that fatigue after long periods without sleep has a negative impact on performance and accuracy for safety. [31,32] Workers in the "transport/postal services" industry must perform their job under time pressure to meet deadlines for appointments or delivery of goods. Furthermore, we previously reported that overwork-related disorders, including karoshi (i.e., death by cerebrovascular and cardiovascular diseases due to overwork) and karojisatsu (i.e., suicide due to overwork), constitute major occupational issues in Japan, particularly among workers in the "transport/postal services" industry. ...
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Long working hours and a lack of sleep have been suggested to negatively affect the safety of workers. Here, we examined the association between long working hours/sleep-related problems and near-misses/injuries in industrial settings using a nationally representative sample of workers in Japan. Based on the composition ratio of workers by industry, sex, and age in Japan, data from a web-based cross-sectional survey for 18,682 participant full-time workers (7,098 female and 11,584 male; mean age, 43.7 [standard deviation 11.1] years) were analyzed. Nearly 30% and 5% of participants reported any types of near-misses during the past six months and injuries during the past year, respectively. For all types of near-misses and some types of injuries, a significant difference in frequency distribution was observed by industry. After adjustment for demographic, job-, and life-related variables, participants who worked long hours (i.e., more than 51 hours per week) were more likely to report job-related near-misses/injuries than those who worked 35-40 hours per week. The presence of sleep-related problems was also significantly related to near-misses and injuries. However, while sleep-related problems were significantly associated with near-misses/injuries in all industries, the association between long working hours and near-misses/injuries differed by industry. Odds ratios for near-misses/injuries were strongly significant in the "transport/postal services" industry for those who worked more than 51 hours per week compared to those who worked 35-40 hours per week. Comprehensive protective measures for workers, including (1) reducing total hours of service/job-related fatigue, (2) maintaining sufficient sleep hours/good sleep, and (3) increasing awareness about the impact of overwork/long working hours and sleep-related problems on workers' safety among employers, workers, clients/customers, and the general public might be effective for preventing near-misses and injuries in industrial settings among workers, especially those who work long hours in the "transport/postal services" industry.
... There is general agreement that shortened or disturbed sleep impairs cognition and performance, leading to an increased risk for fatigue-related incidents. This is illustrated most effectively in laboratory experiments which demonstrate that performance under the short-term effects of sleep deprivation is similar to performance while at the legal limit of alcohol consumption for driving (either 0.05% or 0.08% blood alcohol consumption) [44][45][46][47][48] . However, for those whose jobs involve shiftwork, chronic sleep deprivation can have lasting effects. ...
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A substantial body of literature indicates that shift workers have a significantly higher risk of workplace accidents and injuries, compared to workers in regular daytime schedules. This can be attributed to work during nights which require workers to stay awake during normal sleeping hours and sleep during natural waking hours, leading to circadian desynchronization, sleep disruption and cognitive impairment. A fatigue-risk trajectory model developed by Dawson and McCulloch has been used to describe the series of events which may precede fatigue-related incidents. This includes insufficient sleep opportunities, impaired sleep, fatigue-behavioral symptoms, and fatigue-related errors. The purpose of this paper is to provide examples of control measures along each level of the fatigue-risk trajectory, which include: (i) work scheduling strategies to include breaks for adequate sleep opportunities; (ii) training and educational programs to help workers make best use of recovery times for quality sleep; (iii) fatigue-detection devices to alert workers and safety managers of fatigue-related behaviors and errors. A brief introduction to Fatigue-Risk Management systems is also included as a long-term sustainable strategy to maintain shift worker health and safety. The key statements in this paper represent a consensus among the Working Time Society regarding a multi-level approach to managing occupational sleep-related fatigue.
... 9 The 12-hour work shifts common to FIFO work lead to fatigue, which is detrimental to performance. 21 Fatigue can impair performance to levels equivalent to alcohol intoxication 22 and puts workers at higher accident and injury risk. 23 24 Reducing fatigue and its associated health and safety risks will require investment from both FIFO workplaces and workers. ...
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Objectives Fly-in, fly-out (FIFO) work involves long commutes, living on-site for consecutive days and returning home between shifts. This unique type of work requires constant transitioning between the roles and routines of on-shift versus off-shift days. This study aims to examine health behaviour patterns of FIFO workers and FIFO partners during on-shift and off-shift time frames. Design This study used ecological momentary assessment and multilevel modelling to examine daily health behaviours. Setting FIFO workers and FIFO partners from across Australia responded to daily online surveys for up to 7 days of on-shift and up to 7 days of off-shift time frames. Participants Participants included 64 FIFO workers and 42 FIFO worker partners. Results Workers and partners reported poorer sleep and nutrition quality for on-shift compared with off-shift days. Both workers and partners exercised less, smoked more cigarettes, took more physical health medication and drank less alcohol during on-shift compared with off-shift days. Conclusions FIFO organisations should consider infrastructure changes and support services to enhance opportunities for quality sleep and nutrition, sufficient exercise, moderate alcohol consumption and cigarette cessation for workers on-site and their partners at home.
... Sustained wakefulness of 20-24 h produces decrements equal to those observed with BAC levels of between 0.08%-0.10% (levels legally defined as drunk in many jurisdictions) on tests of psychomotor performance, grammatical reasoning, vigilance, and simulated driving performance (Arnedt et al., 2000(Arnedt et al., , 2001Dawson and Reid, 1997;Lamond and Dawson, 1999). In one study, 24 h of sustained wakefulness was associated with performance impairments equal to those associated with 0.05% BAC on tasks of continuous attention, memory and learning (Falleti et al., 2003). ...
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Fatigue and workplace sleepiness are consequences of modern industrial society. Fatigue is a complex biological phenomenon that occurs as a function of time awake, time-of-day, workload, health, and off-duty lifestyle. Fatigue is a function of two major biological factors – the homeostatic drive for sleep and circadian rhythm of sleepiness. The greatest cause of fatigue is insufficient or disrupted sleep. Excessive sleepiness in the workplace and on highways is a serious safety hazard, and insufficient or disrupted sleep results in numerous accidents and adverse mental and physical health outcomes. Evidence-based strategies that promote better sleep and optimize work/rest schedules can mitigate the impact of fatigue and sleep loss. Proper nap and sleep scheduling, work breaks, modeling and monitoring tools, fatigue detection technologies, and pharmacological countermeasures can be implemented at home and/or in the workplace to reduce performance and safety hazards. Education about obtaining adequate sleep, the dangers of fatigue in terms of both health and cognitive consequences, and the availability of scientifically-proven sleep-enhancement and alertness-management strategies is essential.
... Sleep disturbance has deleterious effects on immunological function, [1,2] the hypothalamic-pituitary-adrenocortical and somatotropic systems, [3][4][5][6][7] and can decrease responsiveness to hypoxic states and inspiratory muscle strength [8,9]. Neurobehavioural alterations such as confusion, delirium and a decline in working memory have also been attributed to sleep disturbance [10][11][12][13]. These effects have been reported to persist even after recovery sleep has been obtained, [11] negating the idea that the effects of sleep disturbance can be overcome once patients are discharged from hospital or high acuity areas. ...
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Background Poor sleep is known to adversely affect hospital patients’ recovery and rehabilitation. The aim of the study was to investigate the perceived duration and quality of patient sleep and identify any environmental factors associated with patient-reported poor sleep in hospital. MethodA cross-sectional study was conducted involving 15 clinical units within a 672-bed tertiary-referral hospital in Australia. Semi-structured interviews to determine perceptions of sleep quantity and quality and factors that disturb nocturnal sleep were conducted with patients and nursing staff. Environmental noise, light and temperature were monitored overnight, with concurrent logging of noise sources by observers. ResultsPatients reported a mean reduction in hospital sleep duration, compared to home, of 1.8 h (5.3 vs. 7.1 h; p < 0.001). The proportions of patients reporting their sleep quality to be poor/very poor, fair and of good quality were 41.6, 34.2 and 24.2% respectively. Patients reported poorer sleep quality than nurses (p < 0.05). Patients, nurses and observers all reported the main factors associated with poor sleep as clinical care interventions (34.3%) and environmental noise (32.1%). Noise levels in all 15 clinical areas exceeded WHO recommended levels of < 30 dB [A] by 36.7 to 82.6%, with peak noise levels of 51.3 to 103.3 dB (A). Conclusion Hospital in-patients are exposed to factors which reduce the duration and quality of their sleep. These extrinsic factors are potentially modifiable through behaviour change and reconfiguration of the clinical environment. The findings from this study provided the foundation for a quality improvement project currently underway to improve patients’ sleep.
... Situation awareness influences performance over and above a number of different cognitive functions, including intelligence, working memory and spatial memory . Lamond and Dawson (1999) found that tasks that are high in workload or are monotonous or require constant attention are most vulnerable to human error. Similarly, Krueger (1989) found that monotonous tasks such as driving were likely to present concerns for vigilance. ...
Article
A common safety issue in the rail industry is a Signal Passed at Danger (SPAD) occurrence in which a train encroaches into a section of track without authority, usually by passing a signal at stop. This study aimed to analyse SPADs using the Human Factors Analysis and Classification System (HFACS) modified to suit the rail industry (HFACS-RR) to examine the human factors involved in the occurrences and identify trends. An analysis of an Australian freight rail organisation's investigation reports (N = 35) into SPADs was undertaken. The analysis revealed at least one HFACS-RR category for each of the events examined. It was found that 97.1% (n = 34) of the events had an ‘operator act’ category, with 74.3% associated with operator errors. Contraventions (e.g. violation of signal approach speed) and distraction (e.g. focus on other non-critical tasks) were the most common types of errors. Mitigation strategies to address these errors are discussed. These include a single methodology to investigate SPADs; train driver performance monitoring; and training strategies focussed on route knowledge, all of which have the potential to reduce SPADs and thereby minimise risk and improve safety. Future research into SPADs may include utilising a larger sample from various organisations, and examining potential differences in the frequency and types of errors of single versus two-man crewed trains.
Article
This work evaluates the potential root causes of fatigue and its relationships with accident risks using a bio-mathematical model approach and a robust sample (N = 8476) of aircrew rosters from the Brazilian regular aviation, extracted from the Fadigômetro database. The fatigue outcomes derive from the software Sleep, Activity, Fatigue, and Task Effectiveness Fatigue Avoidance Scheduling Tool (SAFTE-FAST), which considers the homeostatic process, circadian rhythms and the sleep inertia. The analyses include data from January 2019 until March 2020 and show relevant group effects comparing early 2019 and 2020, with the latter presenting lower fatigue outcomes in most cases. The average minimum SAFTE-FAST effectiveness during critical phases of flight (departures and arrivals) decreases cubically with the number of shifts that elapse totally or partially between mid-night and 6 a.m. within a 30-day period (NNS). As a consequence, the relative fatigue risk increases by 23.3% (95% CI, 20.4–26.2%) when increasing NNS from 1 to 13. The average maximum equivalent wakefulness in critical phases also increases cubically with the number of night shifts and exceeds 24 h for rosters with NNS above 10. The average fatigue hazard area in critical phases of flight varies quadratically with the number of departures and arrivals within 2 and 6 a.m. (NWocl). These findings demonstrate that both NNS and NWocl represent potential root causes of fatigue and therefore should be considered key performance indicators and kept as low as reasonably practical when building aircrew rosters, in order to properly manage the fatigue risk. The effectiveness scores obtained at 30-minute time intervals allowed a model estimate for the relative fatigue risk as a function of the time of the day, whose averaged values show reasonable qualitative agreement with previous measurements of pilot errors in the cockpit. Moreover, the 2019 data revealed a risk exposure factor two times (14%) higher than the figures reported by de Mello et al. (2008) (7%), within 0h00 do 05h59. Tailored analyses of the SAFTE-FAST inputs for afternoon naps before night shifts, commuting from home to station and vice-versa, and bedtime before early-start shifts were carried out using the responses of a questionnaire. The average fatigue hazard area in critical phases of flight increases by 43 to 63% switching off the afternoon naps, 14 to 21% increasing the commuting from one to two hours and 35 to 54% switching off the advanced bedtime criterion, with significant group effects in all cases (p<0.001), evidencing the need of a better and more accurate understanding of these parameters when modelling fatigue risk factors. The non-linear relationships between SAFTE-FAST outcomes and key roster’s parameters, such as NNS and NWocl, provided a novel statistical approach for risk assessment and led to few safety recommendations to the aviation sector regarding regulatory reviews and fatigue risk management and mitigation policies.
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The sleep disturbances of laborers at work lead to acute anxiety and stress stemming from the construction workplace. The sleep deprivation study was conducted on construction laborers in Bengaluru, Karnataka. The paper represents sleep immunity and sleep scores, which track productivity at the construction site. The outcome shows the interconnection between sleep patterns and labour productivity, relating to the concentration level and performance at work. There was a comparative study performed on the calculation of the sleep cycle between the application method and the fit-bit method. The decision-making structure has been interpreted as being sleep-related work, which is related to laborers and may result from an effective decision to withhold the work done by laborers. The productivity of labour in the construction industry has been decreased by up to 12% due to a lack of insufficient sleep. The sleep cycle summarizes the practical implementation of the productivity of labour in the construction industry, which has been decreasing gradually due to a lack of sleep. 1.INTRODUCTION The construction sector in India exercises a prioritized role in development, as it generates investment opportunities [1]. The industry is split and occupied by high-ranking companies that are a part of many construction sectors. Construction labour productivity is influenced by factors such as technology, labour organization, management, overtime and turnover, real wage trends, and sleep deprivation [2-4]. The improper sleep of laborers will cause accidents while they are working on-site and reduce the productivity of workers at the construction site [5,6]. The body condition of the mind, which typically recollects for many hours every night, states that the nervous system is inactive; thus, there will be closed eyes, the muscles relax, and practically consciousness is suspended [7-10]. The symptoms of sleep deprivation are droopy eyelids and general discomfort. Sleep is considered periodically as the state of body and mind and can be characterized by altering consciousness, which is inhibited by sensory activity, which reduces the activity of muscles and inhibition of nearly all muscles that are voluntary active during rapid eye movement sleep and can be reduced by surrounding interaction [11]. The suggested sleep time for aged people is 7 to 8 hours a night. Few human beings need 6 hours or 9 hours of sleep in a day. Adults over the age of 75 require 7-8 hours of sleep per day [12].During pregnancy, women require several hours of rest. A human being usually sleeps for eight hours during the night at the age of 50 and more than five and a half hours a night between the ages of 45 and 50. A 75-year-old in good health requires approximately six and a half hours of sleep per night [13-15].The restoration of body powers is performed during natural periodic sleep [16]. Natural periodic sleep time is associated with psychological and subjective nature, with overall life satisfaction [17]. If the quality of sleep is not of sufficient quality, it will impact walking activities and could even affect long-term health [16]. The sleeping hours of individuals are 6 hours or less, contributing 70% to the higher mortality rate than those who sleep 7 or 8 hours during the night [17]. There are five stages of sleep in a human being: awake sleep, deep sleep, light sleep, and REM sleep [18]. Rem sleep is divided into two types: rapid eye movement sleep and nonrapid eye movement sleep [19]. The pattern of sleep that has been recorded provides the sleep score after the calculation of different stages of sleep [20]. Sleep deprivation has an effect on shift workers that will gradually decrease the productivity growth in their daily work. Shift work reduces both the quality and the quantity of sleep. Sleep individuals are less ambitious and less productive [21]. Researchers have found that the amount of sleep required for adults per day will be approximately 7 hours for completely reviving results, but most get less than 7 h, resulting in a sleep deficit. As a result, sleep deprivation occurs. Outcomes are affected by sleep deprivation in several ways [22-24]. The negative effect of sleep deprivation has a greater influence on the brain and cognitive processes [25]. During the years of college, many pupils were speciated about the capital value of human and knowledge capital, which provides jobs, and when pupils flourished in managing techniques that survived their studies [26]. The two management skills are required for cognition and leadership, which have significantly increased knowledge about written works in documents [27-29].The different stages of sleep will help
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Fatigue is lethargy and seen as unpleasant experience that occurs from physical labour or mental exertion. Fatigue can be either physical or mental. This paper examines the role of physical fatigue and mental fatigue in the relationship between physical isolation variables (social isolation and loneliness) and safety behaviour (safety compliance and safety participation). A cross-sectional study with data were collected by means of a questionnaire among oil and gas workers (foreign employees working at a remote oil and gas field site located in Kuwait), during a 3-month period (from October 2018 to December 2018). Regression analyses (bivariate and hierarchical), carried out on 387 responses, were employed to test the hypothesized model relating physical isolation variables, fatigue levels, and safety behaviour. The results provide support for the role of mental fatigue in mediating the relationship between loneliness and both types of safety behaviour (compliance and participation). Results indicate that mental fatigue is associated with feeling lonely and has negative effect on safety behaviour, which indicated a greater risk of injury incident rates. The study findings should facilitate the improvement of employee safe behaviour through monitoring workers’ fatigue levels. Moreover, they may enable prompt intervention and help to contribute to the development of recommendations that broaden our understanding of the effects of isolation and remote work in the context of workplace safety. The implications of these results for physical isolation, fatigue and/or safety behaviour interventions in the industry are discussed.
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OCCUPATIONAL APPLICATIONS We conducted a study to evaluate fatigue and workload among workers performing complex assembly tasks. We investigate several predictors of fatigue, including subjective workload estimates, sleep duration, the shift being worked, and production levels. High levels of fatigue were reported in one-third of the shifts evaluated. The main predictors of high fatigue were workload estimates, working evening shifts, and baseline fatigue. Among the six dimensions of workload, only mental demand and frustration were predictors of high fatigue. Mental demand was also rated highest. Participants reported less than seven hours of sleep in 60% of the nights evaluated. These results suggest that managers and supervisors should consider cognitive workload as a key contributing factor to fatigue in complex manual assembly. Similarly, work schedule planning should consider shift duration, start times, and end times, because of the negative influence on fatigue and the potential disruptions on sleep among workers.
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Im Rettungsdienst ist die Verfügbarkeit rund um die Uhr an sieben Tagen in der Woche (24/7) unumgänglich. Auch der Krankentransport unterliegt mitunter wechselnden Schichten und Arbeiten an Sonn- und Feiertagen. Da Schichtarbeit im Rettungsdienst und Krankentransport unvermeidbar ist, ist es erforderlich, Ansätze und Kriterien zu entwickeln, um Schichtmodelle so gesundheitsgerecht wie möglich zu gestalten.
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Driving a car is a complex and potentially risky activity in people’s everyday life, and it requires the full involvement of physiological and cognitive resources. Any loss of these resources can cause traffic accidents. For example, drowsy driving affects the ability to adapt, predict and react to unexpected events. A solution to this problem is the adoption of Advanced Driver Assistance Systems (ADAS), which can warn the driver if sleepiness is detected. Thus, they should include a Driver Monitoring System (DMS) to understand, measure and monitor human behaviour in different scenarios. This article is focused on detecting driver drowsiness by using non-intrusive measures such as the behavioural approach, as it is the most promising solution to use in real vehicles. The developed framework allows the extraction of drowsiness-related measures by analysing the driver’s face with a standard camera. First, a face detection stage identifies the driver face in a video frame. Then, a set of facial landmarks locations are identified. These landmark points are used to estimate the head orientation and to detect when a blink occurs. By monitoring properly defined ocular variables, the degree of driver drowsiness is detected through a Fuzzy Inference System (FIS)
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Background: Occupational fatigue is a key issue in the rail industry that can endanger staff, passenger, and train safety. There is a need to demonstrate the relationship between workload, fatigue, and performance among rail staff. Objective: The present study, conducted in the workplace in realistic situations, integrating both subjective and objective measurements, aimed at demonstrating the relationship between workload, fatigue, and cognitive performance with a rail staff sample. Methods: The "After-Effect" technique was applied in the current study. Online diaries and cognitive performance tasks were used to assess the fatigue, work experiences, and performance of rail staff before and after work on the first and last days of one working week. Results: Reported fatigue was greater after work on both the first and last day of the working week. There were large individual differences in the change in fatigue and workload ratings. Analysis of covariance with age and the pre-work performance score as covariates and the post-work performance score as the dependent variable showed that high levels of fatigue were associated with impaired performance on both the visual search and logical reasoning tasks. Workload had fewer effects on performance than fatigue. Conclusion: This field study provided evidence for the relationship between work-related fatigue and performance impairment. The findings show the need for future work on predicting fatigue-related performance decrements, and the necessity of providing interventions and support so that the risk to safety can be reduced.
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Both sleep- and task-related factors are thought to contribute to driver fatigue, with each factor individually associated with deteriorated driving performance. However, the relative and combined effects of these factors in the context of monotonous driving have not been well studied. This study (N = 60) investigated lateral and longitudinal vehicle control, subjective fatigue and physiological response (EEG) during three 10-minute periods of time-on-task spread across a monotonous, 2-hour simulator drive. Level of physiological sleep-need was manipulated between participants by varying the instructed time spent in bed on the night before testing (≤5h or ≥ 8 h). In addition, half of the participants in each sleep group read the applicable speed limit from periodic roadside signs whereas the others performed an arithmetic calculation, displayed on the signs, to determine the speed limit. This task manipulation has been demonstrated to reduce performance decrements over time. Results demonstrated effects of time-on-task and sleep need on self-report ratings, an effect of time-on-task on EEG indices, and an interaction of sleep-need and time-on-task on an EEG index of mental workload and on the lateral control measure of driving performance. There were no significant effects on the measure of speed variability. These results confirm that both sleep-need and time-on-task negatively affect driver state, and that time-on-task decrements in driver performance can occur in the absence of heightened sleep-need. Results also suggest that drivers with heightened sleep-need could protect their performance for a short time, perhaps by exerting effort to compensate for reduced capacity. The secondary task did not counteract declining performance.
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In this abstract we would like to provide some exciting concrete information including the article's main impact and significance on expert and intelligent systems. The main impact is that the PTC expert intelligent system fills in the gaps between the human and software decision making processes. This gap analysis is analyzed via empirical triangulation of rail worker data collected from its groups, individuals and the rail industry itself. We utilize an expert intelligent system PTC information technology application to both measure and to improve the alertness of the groups and workers in order to improve the overall safety of the railways through reduced human errors and failures to prevent accidents. Many individual differences in alertness among military, railroad, and other industry workers stem from a lack of sufficient sleep. This continues to be a concern in the railroad industry, even with the implementation of positive train control (PTC) expert system technology. Information technology aids such as PTC cannot prevent all accidents, and errors and failures with PTC may occur. Furthermore, drug interventions are a short-term solution for improving alertness. This study investigated the effect of sleep deprivation on the alertness of railroad signalmen at work, individual differences in alertness, and the information technology available to improve alertness. We investigated various information and communication technology control systems that can be used to maintain operational safety in the railroad industry in the face of incompatible circadian rhythms due to irregular hours, weekend work, and night operations. To fully explain individual differences after the adoption of technology, our approach posits the necessary parameters that one must consider for reason-oriented action, sequential updating, feedback, and technology acceptance in a unified model. This triangulation can help manage workers by efficiently increasing their productivity and improving their health. In our analysis we used R statistical software and Tableau. To test our theory, we issued an Apple watch to a locomotive engineer. The perceived usefulness, perceived ease of use, and actual use he reported led to an analysis of his sleep patterns that eventually ended in his adoption of a sleep apnea device and an improvement in his alertness and effectiveness. His adoption of the technology also resulted in a decrease in his use of chemical interventions to increase his alertness. Our model shows that the alertness of signalmen can be predicted. Therefore, we recommend that the alertness of all railroad workers be predicted given the safety limitations of PTC.
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This article describes the results from a meta-analytic review of 55 studies and 78 independent samples containing information about the demographic, contextual, and psychological factors associated with alcohol and drug abuse among United States military personnel. In terms of demographics, results from this analysis reveal higher levels of substance abuse among personnel who are male, younger, have less education, are unmarried, and who are of a lower military rank (E1-E3). In terms of the military context, rates of substance abuse are greater for personnel with combat exposure and a recent or lengthy deployment. Finally, rates of substance abuse are higher among personnel reporting specific psychological symptoms, including negative emotionality, impulsivity, and symptoms associated with depression, posttraumatic stress disorder (PTSD), and traumatic brain injuries (TBI). This study suggests that a number of sociodemographic, psychological, and contextual factors are related to the odds that a military service member engages in high levels of substance abuse. The results provide a strong foundation for the development of interventions aimed toward vulnerable populations in the US military.
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Resente werke van &apos;n hoë standaard in die vakgebied Ergonomika of soos dit in die V.S.A bekend staan as Human Factors, of Engineering Psychology as &apos;n afgeleide vorm, is nie volop nie.
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Three levels of working memory load of a visual search (Memory and Search) task were tested in a 72-hour sleep deprivation paradigm. General performance and accuracy decrease over time with monotonic and rhythmic components. The signal detection discriminability index, d', decreases monotonically with rhythmic variations. The index of response bias, β, shows no monotonic trend, but significant circadian rhythmicity. The extent of the monotonic and rhythmic changes in accuracy and in d' is directly related to the level of working memory load. The amplitude of the circadian component of accuracy and d' is enhanced for the higher levels of working memory load. The implication of potentiated circadian rhythmicity as a function of cumulative sleep loss is discussed.
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Safety on shift systems will depend, at least in part, on the adjustment of shiftworkers' circadian (c.24h) rhythms in performance capabilities which will in turn depend on their underlying control. In the present study three volunteers lived on a 30h 'day' and performed a range of tasks every 2h (while awake) to allow estimates of the relative magnitude of the endogenous (body clock) and exogenous (masking) components of their rhythms to be made. Performance rhythms were found to differ considerably in this respect with, for example, speed on a 4-choice serial reaction time task appearing to be largely endogenously determined while that on a 5-target Sternberg task was more dependent on exogenous (i.e., 30h) factors. This implies that performance measures may adjust at very different rates to one another to night work, and hence that the optimal form of shift system may vary according to the precise demands of the shiftworker's task.
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Reduced opportunity for sleep and reduced sleep quality are frequently related to accidents involving shift-workers. Poor-quality sleep and inadequate recovery leads to increased fatigue, decreased alertness and impaired performance in a variety of cognitive psychomotor tests. However, the risks associated with fatigue are not well quantified. Here we equate the performance impairment caused by fatigue with that due to alcohol intoxication, and show that moderate levels of fatigue produce higher levels of impairment than the proscribed level of alcohol intoxication.
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The present study validated the nine-point Karolinska Sleepiness Scale (KSS) and the new Accumulated Time with Sleepiness (ATS) scale against performance of laboratory tasks. The ATS scale was designed as a method for integrating subjective sleepiness over longer time periods. The subjects were asked if certain symptoms of sleepiness had occurred and, if so, for how long. Six subjects participated twice. Each time they were kept awake during the night (except for a short nap occurring during one of the nights in a counterbalanced order) and were tested at 2200, 0200, 0400 and 0600 hours. The tests included a 10-minute rest period, a 28-minute visual vigilance task and an 11 -minute single reaction time task. KSS and visual analogue scale (VAS) ratings were given before each test, and ATS ratings were given after. Performance deteriorated clearly, and all three rating scales reflected increased sleepiness with time of night. Scores on the KSS and VAS showed high correlations with performance tasks (mean intraindividual correlations were between 0.49 and 0.71). Performance correlated even higher with the ATS ratings (r = 0.73–0.79). Intercorrelations between rating scales were also high (r = 0.65–0.86). It was concluded that there were strong relations between ratings of sleepiness and performance, that the ATS rating scale was at least as good as the other scales and that the ratings were affected by type of task.
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The effects of sloop deprivation upon performance vary widely with the nature of the work being carried out. In the present study impairment was almost complete towards the end of 20 min repetitive serial responding and 30 min inspection work (vigilance). On the other hand, tactical decision taking of a complex, but absorbing and realistic nature was completely unaffected by the same degree of stress oven towards the end of one hour's continuous work. What are the features of a task which determine whether its performance will be impaired by loss of sleep or not? Two are suggested. A task will be vulnerable to sleep deprivation (1) as it is complex, and (2) as it is lacking in interest, incentive and reward. Of the two factors, that of incentive may be the more influential, such that a highly complex task may be little affected by sleep deprivation if it is complex in an interesting or rewarding way.
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Prolonged work scenarios with demands for sustained performance are increasingly common. Because sleep loss inevitably compromises functioning in such situations, napping has been proposed as a countermeasure. The optimal timing of the nap relative to its benefits for performance and mood is not known, however. To address this issue, 41 healthy adults were permitted a two-hour nap at one of five times during a 56-hour period of intermittent work, with no other sleep. Naps were placed 12 hours apart, near the circadian peak (P) or trough (T), and were preceded by 6(P), 18(T), 30(P), 42(T), or 54(P) hours of wakefulness. Work test bouts occurred every few hours and consisted of a variety of psychomotor and cognitive tasks as well as mood scales completed at the beginning, middle and end of each bout. A total of eight performance and 24 mood parameters were derived from the bouts and compared between groups at all test points prior to and following the naps. An estimate of the extent to which each nap condition differed from the control (P54) condition was derived by totalling the proportion of test points that yielded statistically significant results relative to the total number of tests conducted both before and after naps.Although all performance and most mood parameters displayed a circadian-modulated deterioration as the protocol progressed, a nap appeared to attentuate the extent of this change in all performance parameters but not in mood parameters. Overall, the timing of the nap across days and within the circadian cycle was irrelevant to its effect on performance, suggesting that it diminished the intrusion of sleepiness into behavioural functioning, even though subjects were phenomenally unaware of this benefit.
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This study examined the effects of restricting sleep to the first or second half of the night on the composition of sleep and on performance. Eight young women who regularly slept for 8–8.5 hrs a night had their sleep restricted to the first or second half of the night for two consecutive nights. Performance of a 20-min unprepared simple reaction time task was measured at fixed times of day for the two restricted sleep conditions and for a full night sleep control condition. Restricting sleep to the second half of the night produced higher amounts of REM sleep and Stage 4 sleep and lower amounts of Stage 2 sleep compared to restricting sleep to the first half of the night. Both restricted sleep conditions impaired performance relative to the full night sleep control, and performance was worse after two nights of restricted sleep than after one night of restricted sleep. The results show that the effects of a restricted sleep regime on the composition of sleep are partly a function of the time of night to which sleep is restricted. It is suggested that the performance deficits are due to loss of sleep per se rather than due to any change in the composition of sleep.
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Men 18–22 and 40–49 yrs old were repeatedly given a battery of monitoring, persistence, and cognitive tasks over an extended period of sleep deprivation. The older subjects, who generally exhibited superior performance, were also more affected by the acute deprivation of sleep.
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Because of low cognitive demands and infrequent performance assessment, previous sleep-loss studies may have provided conservative estimates of the cognitive deficits that can occur during sustained, intensive, military operations. The research described here addresses the limitations of earlier studies by requiring and measuring performance on a continuous basis in a computerized laboratory environment. During a 54-h period of wakefulness, subjects were required to continuously monitor and act upon information being transmitted over a communication network while their performance on cognitive tests, which were embedded in and distributed around the message traffic, was continuously evaluated. The results show that this cognitively demanding environment produces greater mood and performance decrements as a function of sleep loss than previous, less-demanding studies. The methodology is described in detail, and the implications of the experimental findings are discussed.
Article
DESCRIBES A SIMPLE REASONING TEST INVOLVING THE UNDERSTANDING OF SENTENCES OF VARIOUS LEVELS OF SYNTACTIC COMPLEXITY. IT IS SHORT, EASILY ADMINISTERED, AND RELIABLE. PERFORMANCE CORRELATES WITH INTELLIGENCE (.59) AND HAS PROVED TO BE SENSITIVE TO A NUMBER OF STRESSES. (PsycINFO Database Record (c) 2003 APA, all rights reserved)
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The aim of the study was to investigate the effect of spending one night without sleep on the performance of complex cognitive tasks, such as problem-solving, in comparison with a purely short-term memory task. One type of task investigated was immediate free recall, assumed to reflect the holding capacity of the working memory. The other type of task investigated was represented by syntactical reasoning and problem-solving tasks, assumed to reflect the processing (the mental transformation of input) and monitoring capacity of the working memory. Two experiments with a repeated-measures design were performed. Experiment 1 showed a significant decline in performance as a function of sleep loss on Raven's progressive matrices, a problem-solving task. No other main effect of sleep loss was found. Experiment 2 had a different order between tasks than Experiment 1 and the time without sleep was increased. A number-series induction task was also used in Experiment 2. A significant, negative effect of sleep loss in performance on Raven's progressive matrices was found in Experiment 2. The effects of sleep loss on the other tasks were nonsignificant. It is suggested that Raven's progressive-matrices task reflects the ability to monitor encoding operations (selective attention) and to monitor mental "computations".
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Performance in a driving simulator was evaluated as a function of locus of control, perceived alcohol ingestion (no alcohol versus a no-alcohol placebo), and sex. Using a pretest-posttest design, an analysis of covariance was performed using the pretest performance on a driving simulator as the covariate. There were 10 men and 10 women in each of four groups. As predicted, the external-scoring placebo subjects made more posttest errors than did the internal-scoring placebo group or either of the no-alcohol control groups. This indicated that the external-scoring placebo subjects were more affected by what they expected to happen than their actual physiological state warranted. A difference was also found in which external-scoring women made more errors than did any other group. This was an unexpected finding which, being inconsistent with previous findings involving sex, warrants further research.
Article
Ethyl alcohol's known ability to produce reliable decrements in pilot performance was used in a study designed to evaluate objective methods for assessing pilot performance. Four air carrier pilot volunteers were studied during eight simulated flights between San Francisco and Los Angeles in a Boeing 727-232 simulator. Two flights were conducted at each of four target blood alcohol levels, 0, 0.025, 0.050, and 0.075%. Each flight lasted about 1 h. Flights were conducted with full crews in a full simulated ATC environment. Data from direct observations and videotapes were used to examine discrete errors committed by the subjects. Total errors increased linearly and significantly with increasing blood alcohol. Planning and performance errors, procedural errors and failures of vigilance each increased significantly in one or more pilots and in the group as a whole. Failures of crew coordination were not associated with blood alcohol level. Serious errors increased significantly even at the lowest alcohol level studied, 0.025% (25 mg/dl), compared with control values.
Article
This study compared subjective and performance dose effect profiles of oral alcohol and smoked marijuana. Male subjects (N = 6) with histories of moderate alcohol and marijuana use received three doses of alcohol (0, 0.6, 1.2 g/kg) and three doses of marijuana (0, 1.3, 2.7% delta 9-THC) in a double-blind, randomized crossover design. Physiological indices indicated that active drug was delivered to subjects dose dependently. Alcohol produced dose-related elevations on several subjective measures of drug effect. The high dose of alcohol impaired performance on circular lights, tracking and digit-symbol substitution (DSST) tasks, whereas the low alcohol dose impaired only circular lights performance. Marijuana produced elevations on subjective report measures, but effects were similar for the two active doses. Minimal performance impairment was seen with marijuana on only one measure (DSST speed). The subjective and performance effect profiles produced by smoked marijuana were similar to that of the low (0.6 g/kg) dose of alcohol. These data are useful for understanding the relative performance impairment produced by alcohol and marijuana and the relationship between their subjective and behavioral effects.
Article
The stress and long working hours of medical residency have become the basis for controversy over whether current training structures and processes adversely affect residents' skills and well-being and the quality of patient care. The authors measured cognitive and skills performances of 45 sleep-deprived pediatrics residents by using questions like those on the pediatrics board certification examination and using patient-care tasks that required coordination and dexterity. The residents were randomly divided into two groups--one stayed awake for 24 hours, the other for 34 hours--and were tested on cognitive and skills performances before and after sleep deprivation. Sleep deprivation did not have a significant effect on cognitive performance. Of the three skills tested, the residents overall needed more time to perform umbilical artery catheterization, but the group deprived of sleep for 34 hours performed vein cannulation more quickly than the group deprived for 24 hours. Implications for these findings are discussed in the context of the ongoing controversy over the structure and process of medical education.
Article
Three matched groups of five subjects, designated sleep deprived with incentive (I), sleep deprived without incentive (NI), no sleep deprivation, no incentive control (C), were run on separate occasions. All underwent h of auditory vigilance performance three times per 24 h, following a baseline non-incentive day. During deprivation, group I were given attractive monetary reward for “hits” and were “fined” for false alarms and misses. These stakes were doubled for each successive deprivation day in an attempt to combat the increasing tiredness effects. At the end of deprivation, groups I and NI were allowed 8 h of recovery sleep, and were tested again, without incentive for I. It was found that incentive was able to maintain performance (hits and d′) at baseline levels for up to 36 h of deprivation. Thereafter, although this performance fell, it remained significantly better than that for NI, for a further day only. Despite substantive rewards on the third day, incentive was ineffective. Following the recovery sleep, performance returned to normal. Although no significant time-of-day effects were found in performance during the normal waking hours, it was apparent that the major decline per 24 h occurred through the night, with a levelling off in the day.
Article
Organic solvents are used frequently in industry and workers are often exposed to various combinations of these chemicals. Several are CNS depressants, and the purpose of this experiment was to assess the behavioral effects of 4-hour inhalation exposures to two solvents, toluene and methyl ethyl ketone (MEK) alone and combined. Ethanol at 0.08% blood levels was used as a positive control. A total of 144 paid volunteers were randomly assigned to one of eight treatment combinations in a series of four two-group between subjects studies. Testing was carried out in an exposure chamber, and participants were tested before, during, and after the treatment or control condition on three performance tasks. The tasks measured alertness and psychomotor function and produced a total of 28 measures on each individual over the approximate 8 h of testing. Results indicated that toluene at 100 ppm produced a small but significant impairment on one measure of a visual-vigilance task by lowering the percentage of correct hits. MEK at 200 ppm produced no interpretable significant effects on any of these measures. Additivity was not evident when individuals were exposed to MEK (100 ppm) and toluene (50 ppm) in combination, as no significant performance differences were noted. Ethanol, at 0.08%, affected both the visual-vigilance and a choice-reaction time task at statistically significant levels on two measures, confirming the sensitivity of these two tasks to CNS depressants.
Article
Thirty young male volunteers participated in a study of sustained continuous performance using a variety of computer-based tasks. After 6 hrs of recorded sleep, 10 subjects were assigned to perform continuously for 42 hrs without break. Three of these subjects were unable to complete the 42-hr assignment, and 8 of the 10 suffered psychological events such as hallucinations and disorientation. Ten subjects permitted six 1-hr naps over the 42 hrs performed more successfully than those allowed no sleep. Ten subjects permitted one 6-hr rest period performed best of all. Fatigue effects appeared after 6 hrs. Time-of-day (circadian) effects were at times stronger than fatigue.
Article
There is a need for a standard by which to compare the degree of subjective and behavioral impairment caused by anesthetic drugs, because anesthesiologists may not be able to gauge how extreme or important a statistically significant change in psychomotor functioning is. This study examined the psychomotor and subjective effects of alcohol at blood concentrations equal or greater than 0.10% as a standard with which to compare those effects caused by sedative and analgesic agents commonly used in ambulatory surgery. Twelve healthy human volunteers (11 men and 1 nonpregnant woman), with an average age of 28 yr (range 24-34 yr) and an average alcohol consumption of four drinks per week, were selected in this institutional review board-approved study. Each subject was exposed to five drug conditions (70 mg/70 kg propofol intravenously, 2 mg/70 kg midazolam intravenously, 50 micrograms/70 kg fentanyl intravenously, 0.8 g/kg alcohol orally, and placebo orally and intravenously) in a double-blind randomized fashion over five weekly sessions. Testing was done at baseline and at different intervals until 240 min after drug administration. Testing included psychomotor performance (Maddox Wing, eye-hand coordination, auditory reaction time test, and digit symbol substitution test), subjective effects (strength of drug effect scale, drug liking scale, and visual analog scale), and short-term memory. Psychomotor performance was used as an index of objective impairment, and mood was used as an index of subjective impairment. After consumption of the alcoholic beverage, a blood alcohol level of 0.11 +/- 0.003% (mean +/- SE) was obtained at 15 min after injection. The study drugs not only produced statistically significant impairment (i.e., impairment greater than that seen with placebo) but also, at one or more times after injection, produced impairment similar to that observed with alcohol at a blood alcohol concentration of 0.11%. Midazolam produced a similar degree of impairment to that of alcohol for a longer duration than did fentanyl and propofol. This study provides evidence that degree of impairment caused by sedative and analgesic drugs used in ambulatory surgery is similar to that obtained with a dose of alcohol that produces a blood alcohol concentration of 0.11%. We suggest that anesthesiologists can use alcohol as a standard by which to assess degree of impairment produced by drugs used for sedation/analgesia.
Article
The present study validated the nine-point Karolinska Sleepiness Scale (KSS) and the new Accumulated Time with Sleepiness (ATS) scale against performance of laboratory tasks. The ATS scale was designed as a method for integrating subjective sleepiness over longer time periods. The subjects were asked if certain symptoms of sleepiness had occurred and, if so, for how long. Six subjects participated twice. Each time they were kept awake during the night (except for a short nap occurring during one of the nights in a counterbalanced order) and were tested at 2200, 0200, 0400 and 0600 hours. The tests included a 10-minute rest period, a 28-minute visual vigilance task and an 11-minute single reaction time task. KSS and visual analogue scale (VAS) ratings were given before each test, and ATS ratings were given after. Performance deteriorated clearly, and all three rating scales reflected increased sleepiness with time of night. Scores on the KSS and VAS showed high correlations with performance tasks (mean intraindividual correlations were between 0.49 and 0.71). Performance correlated even higher with the ATS ratings (r = 0.73-0.79). Intercorrelations between rating scales were also high (r = 0.65-0.86). It was concluded that there were strong relations between ratings of sleepiness and performance, that the ATS rating scale was at least as good as the other scales and that the ratings were affected by type of task.
Article
Young subjects are frequently involved in sleep-related accidents. They could be more affected than older drivers by sleep loss and therefore worsen their driving skills quicker, or have a different perception of their level of impairment. To test these hypotheses we studied variations of reaction time (RT), a fundamental prerequisite for safe performing, as measured by lapses, i.e. responses > or = 500 ms and self-assessment of performance and sleepiness after a night awake and after a night asleep in a balanced crossover design in young versus older healthy subjects. Ten young (20-25 years old) and 10 older volunteers (52-63 years old) were tested with and without 24 h of sleep deprivation. Without sleep deprivation, RTs were slower in older subjects than in the younger ones. However, after sleep deprivation, the RTs of young subjects increased while that of the older subjects remained almost unaffected. Sleepiness and self-perception of performance were equally affected in both age groups showing different perception of performance in the age groups. Our findings are discussed in terms of vulnerability to sleep-related accidents.
Comprehensive study of the sleep of shiftworkers. The twenty four hour workday
  • D I Tepas
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The topology of performance curves during 72 hours of sleep loss
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Effects of been used. Thus, protocols using simulators could be used to sleep deprivation on cognitive ability and skills of paediatric model real-life settings and establish a more accurate estimate of residents
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fatigue and actual driving, simulators of varying realism have Storer, J., Floyd, H., Gill, W., Giusti, C. and Ginsberg, H. Effects of been used. Thus, protocols using simulators could be used to sleep deprivation on cognitive ability and skills of paediatric model real-life settings and establish a more accurate estimate of residents. Academic Med., 1989, 64: 29–32.
is no guarantee that all the functions involved in real-life tasks, Linde, L. and Bergstrom, M. The effect of one night without sleep on such as driving, were utilised and assessed. An alternative problem-solving and immediate recall
tests to evaluate the effects of fatigue on performance there 1982. is no guarantee that all the functions involved in real-life tasks, Linde, L. and Bergstrom, M. The effect of one night without sleep on such as driving, were utilised and assessed. An alternative problem-solving and immediate recall. Psychological Research, 1992, approach would be to simulate the actual task as accurately 54 (2): 127–136.
Comprehensive study the BAC equivalence for the performance decrement associated of the sleep of shiftworkers. The twenty four hour workday. with sleep loss and fatigue
  • D I Tepas
  • J D Walsh
  • D Armstrong
Tepas, D. I., Walsh, J. D. and Armstrong, D. Comprehensive study the BAC equivalence for the performance decrement associated of the sleep of shiftworkers. The twenty four hour workday. with sleep loss and fatigue. Proceedings of a symposium on variations in work–sleep schedules. U.S. Department of Health and Human Services, 1981, 419–433.
The topology of performance curves during 72 hours of sleep loss: Wilkinson, R. T. Effects of up to 60 hours sleep deprivation on different types of work
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