Simon Folkard

Simon Folkard
Swansea University | SWAN · Department of Psychology

PhD, DSc

About

251
Publications
203,213
Reads
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13,882
Citations
Additional affiliations
October 2011 - September 2019
Paris Descartes, CPSC
Position
  • Professor
April 2004 - July 2004
Liberty Mutual Research Institute for Safety
Position
  • Researcher
October 2003 - September 2011
Paris Descartes, CPSC
Position
  • Professeur Invite
Education
October 1971 - December 1989
Birkbeck, University of London
Field of study
  • Chronopsychology
October 1968 - December 1972
Birkbeck, University of London
Field of study
  • Developmental Psychology
October 1965 - June 1968
Birkbeck, University of London
Field of study
  • Psychology

Publications

Publications (251)
Article
Around-the-clock staffing in safety-critical environments calls for an accurate risk assessment of work schedules. In this paper we introduce and evaluate an hourly version of the “Risk Index”, an established risk model in the UK rail industry. This “Hourly Risk Index” is the first risk-based model that allows the prediction of risk at the hourly l...
Article
Full-text available
Self-report tools that measure circadian rhythms have focused primarily on phase. We add to the sparse literature on assessing amplitude and stability. We randomly recruited 1,163 participants who completed several measures. The correlation between the LV scale (amplitude) and FR scale (stability) was −0.12 (p < 0.01). As expected, amplitude was ne...
Article
Background: It is well-established that sleep regulates immune functions. Immunological functions are dependent on circadian rhythms and regular sleep as both have an impact on the magnitude of immune responses following antigenic challenge (eg, in vaccination). Here we investigated whether nocturnal shift work can influence post-vaccination respo...
Conference Paper
Many notorious disasters in the last few decades may have been correlated with fatigue or human error. Detecting the level of fatigue from a person, in order to monitor and predict possible risk situations, has become a major concern. A person alertness model is used to produce data in a realistic manner, similarly to a Karolinska Sleepiness Scale...
Article
Full-text available
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 circadia...
Article
Full-text available
Fatigue is a major risk factor for occupational 'accidents' and injuries, and involves dimensions of physical, mental, and muscular fatigue. These dimensions are largely influenced by temporal aspects of work schedules. The "Risk Index" combines four fatigue-related components of work schedules to estimate occupational 'accident' and injury risk ba...
Conference Paper
Full-text available
Introduction Sleep regulates immune functions. We investigated whether nocturnal shiftwork can influence the immune response upon vaccination. Methods Thirty four healthy workers (23 females), nocturnal and diurnal shifts (17 day workers), were vaccinated against Meningococcal C (MenC) meningitis. Sleep was recorded polysomnographically and the co...
Article
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Holt suggests that the shift workers in our study1 may have been performing worse than day workers because they performed the tests during their ‘biological night’ (ie, during the day). It is indeed the case that the cognitive tests were administered during the day, but the available evidence suggests that even the vast majority (>95%) of permanent...
Article
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Objectives Shift work, like chronic jet lag, is known to disrupt workers’ normal circadian rhythms and social life, and to be associated with increased health problems (eg, ulcers, cardiovascular disease, metabolic syndrome, breast cancer, reproductive difficulties) and with acute effects on safety and productivity. However, very little is known ab...
Article
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The aim of the present study was to define the nature of individual differences in shift work tolerance (SWT). This was investigated by an exploratory factor analysis of scores from a wide range of established instruments designed to measure sleep, sleepiness, fatigue, social functioning, as well as physical and mental health. Data were collected f...
Article
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Early shift start time and night shifts are associated with reduced sleep duration and poor sleep quality that often lead to increased fatigue levels, performance decrements and adverse safety and health outcomes. This study investigates the impact of shift starting time on sleep patterns, including the duration and quality of sleep and alertness/s...
Article
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Bipolar disorder (BD) is a chronic psychiatric condition characterized by recurrences of depressive and (hypo)manic episodes. Patients in remission report a wide range of sleep and circadian disturbances that correlate with several outcomes measures such as functioning or physical health. The most appropriate way to measure these abnormalities in c...
Article
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The aim of the present study was to investigate the effects of the duration and timing of rest breaks on traumatic injury risk across a shift in a relatively large sample of hospitalized workers with severe work-related hand injury in the People's Republic of China (PRC). Hospitalized workers from multiple industries with severe work-related trauma...
Article
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Circadian rhythm disturbances have been associated with bipolar disorder (BD) during both the mood episodes and the periods of remission. Circadian phase preferences for the evening have been reported for remitted patients, whereas the amplitude and stability of their rhythms have never been assessed using questionnaires. The primary aim of our stu...
Article
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Occupational injury is associated with numerous individual and work-related risk factors, including long working hours and short sleep duration; however, the complex mechanisms causing such injuries are not yet fully understood. The authors used structural equation modeling (SEM) as a novel approach to examine fatigue-related direct and indirect po...
Article
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The "Bergen Shift Work Sleep Questionnaire" (BSWSQ) was developed to systematically assess discrete sleep problems related to different work shifts (day, evening, night shifts) and rest days. In this study, we assessed the psychometric properties of the BSWSQ using a sample of 760 nurses, all working in a three-shift rotation schedule: day, evening...
Article
Objectives: This study examined the effects of age, gender, and retirement on the subjective frequency of various sleep problems in individuals on a normal work schedule. Design: Data were taken from the VISAT study (Aging, Health, - Work), which allowed both cross-sectional and longitudinal aspects of age-related changes to be examined. Settin...
Article
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Many of the health problems that are more prevalent among shiftworkers are thought to be linked to their heightened susceptibility to metabolic syndrome, i.e., the association of even moderate degrees of visceral obesity, dyslipidemia, abnormal blood pressure, and serum glucose levels in the same individual. Although previous studies have identifie...
Article
Full-text available
Fatigue has been linked to adverse safety outcomes, and poor quality or decreased sleep has been associated with obesity (higher body mass index, BMI). Additionally, higher BMI is related to an increased risk for injury; however, it is unclear whether BMI modifies the effect of short sleep or has an independent effect on work-related injury risk. T...
Book
Full-text available
This report reviews research examining the impact of modern working time arrangements on workers’ health, well-being and workplace safety. Section 1 outlines the theoretical framework underpinning our analysis. It draws together the fundamental features of work schedules and the parameters around which they vary, the broad range of occupational hea...
Article
Full-text available
Long working hours can lead to an accumulation in fatigue that may increase worker's risk of injury. However, it is not known if this association is different for men and women. Our aim was, therefore, to investigate gender differences in the effect of weekly working hours on occupational injury risk. The US National Health Interview Survey is a cl...
Article
Full-text available
Objectives: Rest breaks and other work-related temporal factors, such as time spent on task, influence the accumulation of fatigue, and thus impact occupational injury risk. The aim of this study was to investigate the effect of rest breaks on "time to injury" (the time between start of work and injury) for injured workers treated in a nationally...
Article
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Article
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With workforces in industrialized countries getting older, the study examined how shiftworking affects sleep in later life. Longitudinal data were collected in 1996, 2001, and 2006 from a large sample of employees who were 32, 42, 52, and 62 years old in 1996. Effects of shiftwork were most apparent in middle-aged participants, becoming less appare...
Conference Paper
Full-text available
Abstract Fatigue has been linked to adverse safety outcomes and poor quality or decreased sleep has been associated with obesity (higher body mass index, BMI). Additionally, higher BMI is related to an increased risk for injury; however, it is not clear whether BMI modifies the effect of short sleep or has an independent effect on work-related inju...
Article
The experiment reported here examines the effect of emotion on the recall of self-generated paired associates under conditions of both immediate and delayed retention. The paradigm used was that of Levinger & Clark (1961). The results showed that, with immediate retention, the recall of associates to emotional stimuli was significantly lower than t...
Article
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Two experiments are described that examined the influence of time of day of presentation on immediate and delayed retention, and the potential effects of time of day on retrieval from long-term memory. Time of presentation was found to influence both the immediate and delayed (28 day) retention of information presented in naturalistic contexts. How...
Article
Full-text available
Fatigue is regarded as a major contributor to workplace and highway morbidity and mortality. While the scientific literature is replete with studies that can be traced back more than a hundred years, much remains to be done to improve our knowledge of and ability to alleviate the consequences of fatigue. Moreover, given the dramatic transformation...
Article
Although there has been a significant amount of research on fatigue globally, it remains a major contributor to workplace and highway mortality and morbidity. Given its importance, a Hopkinton Conference was organized to review and discuss the state of knowledge in the area and to define future directions for research aimed at preventing or mitigat...
Article
Full-text available
The Circadian Amplitude and Phase Scale (CAPS) is a new self-report tool that aims to assess amplitude and phase. The CAPS consists of three factors made up of 38 items. Amplitude is posited to be assessed via two of these factors: time awareness (TA) and/or strength of preference (SOP). The remaining factor, phase, is assessed via the existing Pre...
Article
Full-text available
The impact on health and safety of the combination of chronic sleep deficits and extended working hours has received worldwide attention. Using the National Health Interview Survey (NHIS), an in-person household survey using a multistage, stratified, clustered sample design representing the US civilian, non-institutionalized population, the authors...
Article
Full-text available
Shiftwork has been associated with a higher propensity for the development of metabolic disorders and obesity. The aim of the study was to investigate concentrations of glucose, cortisol, and insulin among fixed night workers (n = 9), fixed early morning workers (n = 6), and day workers (n = 7). Food intake was recorded for 7 days using a diary. Bl...
Article
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Many doctors report working excessively demanding schedules that comply with the European Working Time Directive (EWTD). We compared groups of junior doctors working on different schedules in order to identify which features of schedule design most negatively affected their fatigue and well-being in recent weeks. Completed by 336 doctors, the quest...
Article
With the workforces in industrialized countries getting older, this study sought to determine how shiftworking affects sleep in later life. Longitudinal data were collected from a large sample in 1996, 2001, and 2006 from employees who were 32, 42, 52, and 62 years old in 1996. The effects of shift work were most apparent in the early and middle ye...
Article
A forced desynchrony methodology was used to assess postprandial blood glucose in 9 female volunteers during a 3-h period following a mixed meal presented at four times of day (08:00, 14:00, 20:00, 02:00). The influence of time of day on the postmeal glucose responses was evaluated by calculating the area under the curve, largest increase, time tak...
Article
There were 15 healthy female subjects, differing in their position on the “morningness-eveningness” scale, studied for 7 consecutive days, first while living a sedentary lifestyle and sleeping between midnight and 08:00 and then while undergoing a “constant routine.” Rectal temperature was measured at regular intervals throughout this time, and the...
Article
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Eleven subjects, in groups of 2 or 3, have lived in an isolation unit for a period of 30‐h “days”; (lOh sleep, 20h awake and sedentary). Rectal temperature and urinary excretion of potassium and sodium were measured throughout the experiment. Estimates of the phases of raw data indicated dissociation or desynchronization between the rhythms. When t...
Article
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"Permanent" or "fixed" night shifts have been argued to offer a potential benefit over rotating shift systems in that they may serve to maximize circadian adjustment and hence minimize the various health and safety problems associated with night work. For this reason, some authors have argued in favor of permanent shift systems, but their arguments...
Article
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It has long been recognized that older shift workers may have shorter and more disturbed day sleeps between successive night shifts than their younger colleagues. This has given rise to considerable concern over the safety of aging shift workers because of the increasing age of the work force and increases in retirement age. Because there have been...
Article
Full-text available
Mathematical models designed to predict alertness or performance have been developed primarily as tools for evaluating work and/or sleep-wake schedules that deviate from the traditional daytime orientation. In general, these models cope well with the acute changes resulting from an abnormal sleep but have difficulties handling sleep restriction acr...
Technical Report
Full-text available
Published in Transportation Law Journal, Volume 33, Number 3, Fall 2006, Page 295-338. Fatigue management in the transportation industry is a challenge because the industry operates on twenty-four hours a day, seven days a week (24/7). Operations in the maritime, rail, aviation, and the trucking industry are all (24/7). For the freight industry i...
Article
Full-text available
This paper describes our development of Fatigue and Risk Indices that allow users to assess the likely fatigue and risk associated with a given work schedule. Both indices are based on literature reviews and take account of recent developments in the field, especially those related to cumulative effects. The Fatigue and the Risk Indices were both c...
Article
Full-text available
Two hundred and sixty-one shiftworkers from a range of UK industrial and service organizations, took part in a study to determine the impact of the direction of shift rotation on the health and well-being of the individuals concerned. All the systems were continuous, rotating over three shifts. Systems were classified according to whether they dela...
Article
Full-text available
Shiftwork researchers have concentrated on the problems on the night shift, and have tended to neglect the truncation of sleep that can occur before morning, or 'early', shifts. We examined the sleep timing and duration between morning shifts of shiftworkers on a variety of shift systems. The extent of morning shift sleep truncation depended very l...
Article
Individual differences in the phase of circadian (around 24 h) rhythms are thought to be important in determining adjustment to shift work and rapid time-zone transitions. Attempts to predict such phase differences on the basis of paper and pencil ‘personality’ tests have concentrated on extraversion and morningness, of which Kerkhof (1985), in a r...
Article
Full-text available
There is little doubt that productivity and safety can be impaired on the night shift. Two main factors have been identified that may be responsible for this. On the one hand, the circadian rhythm in performance on at least simple tasks is at a low ebb at night, and adjusts only slowly over a span of night shifts. On the other, the day sleeps of sh...
Article
Full-text available
Consistent effects of time of day have been observed in digit span/sequence performance, and in the immediate memory for information presented in prose. However, studies using syntactically unstructured word lists have yielded inconsistent results. Three experiments were conducted that examined the free recall of 15 word lists. In all three, immedi...
Article
Full-text available
Many of the industrial disasters of the last few decades, including Three Mile island, Chernobyl, Bhopal, Exxon Valdez, and the Estonia ferry, have occurred in the early hours of the morning. Follow-up investigations concluded that they were at least partially attributable to human fatigue and/or error. The potential impact of long work hours on he...
Article
Fatigue management in the transportation industry is a challenge because the industry operates on twenty-four hours a day, seven days a week (24/7). Operations in the maritime, rail, aviation, and the trucking industry are all (24/7). For the freight industry in particular, nighttime operations are there is less competition for the roads and rails...
Article
Full-text available
Searching for icons, symbols, or signs is an integral part of tasks involving computer or radar displays, head-up displays in aircraft, or attending to road traffic signs. Icons therefore need to be designed to optimize search times, taking into account the factors likely to slow down visual search. Three factors likely to adversely affect visual s...
Article
Full-text available
The authors recently published a prototypic Risk Index (RI) to estimate the risk of critical errors associated with shift systems. This RI was based on published trends in the relative risk of injuries and accidents, and a simple additive model was proposed to estimate the risk for a given shift system. However, extending the RI to irregular work s...
Article
Full-text available
This study examined the impact of rest breaks on temporal trends in industrial accident risks in an attempt to replicate earlier findings of a linear increase in risk as a function of elapsed time on task. In two separate studies, the trend in work-related injuries were studied in relation to the timing of rest breaks. In study one, comparisons wer...