Philip Tucker
Swansea University, Psychology, Faculty Member
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The study aimed to measure the effects of a 27-h 'day' sleep-wake regime on actigraphic and subjective sleep variables, and to examine the relationships between these variables. Nine subjects spent 30 days and nights in... more
The study aimed to measure the effects of a 27-h 'day' sleep-wake regime on actigraphic and subjective sleep variables, and to examine the relationships between these variables. Nine subjects spent 30 days and nights in the laboratory. After sleeping 8 h for each of 8 nights, the subjects had an imposed 27-h 'day', for 18 'days', remaining in bed for 9 h on each sleep period. Sleep periods therefore started 3 h later each day, although subjects' circadian rhythms stayed entrained to 24 h, because subjects were not isolated from the natural light-dark cycle. Time asleep, subjective sleep efficiency and subjective sleep quality, but not movement during sleep, were found to be significantly affected by time of going to bed. There were significant decreases in movement during recovery sleeps following each of two episodes of 26 h sleep deprivation. Over the study there were significant within-subject correlations between subjective sleep quality and subjective sleep efficiency (rav = 0.65), movement during sleep and subjective sleep efficiency (rav = -0.48), and movement during sleep and subjective sleep quality (rav = -0.26). We conclude that sleep movement, despite its low within- and between-subjects variability, is nevertheless a statistically reliable, but weak, indicator of subjective sleep efficiency and quality.
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Nine healthy females were studied about the time of the spring equinox while living in student accommodations and aware of the passage of solar time. After 7 control days, during which a conventional lifestyle was lived under a 24h... more
Nine healthy females were studied about the time of the spring equinox while living in student accommodations and aware of the passage of solar time. After 7 control days, during which a conventional lifestyle was lived under a 24h "constant routine," the subjects lived 17 x 27h "days" (9h sleep in the dark and 18h wake using domestic lighting, if required). Throughout the experiment, recordings of wrist activity and rectal (core) temperature were taken. The raw temperature data were assessed for phase and amplitude by cosinor analysis and another method, "crossover times," which does not assume that the data set is sinusoidal. Two different purification methods were used in attempts to remove the masking effects of sleep and activity from the core temperature record and so to measure more closely the endogenous component of this rhythm; these two methods were "purification by categories" and "purification by intercepts." The former method assumes that the endogenous component is a sinusoid, and that the masking effects can be estimated by putting activity into a number of bands or categories. The latter method assumes that a temperature that would correspond to complete inactivity can be estimated from measured temperatures by linear regression of these on activity and extrapolation to a temperature at zero activity. Three indices were calculated to assess the extent to which exogenous effects had been removed from the temperature data by these purification methods. These indices were the daily variation of phase about its median value; the ratio of this variation to the daily deviation of phase about midactivity; and the relationship between amplitude and the square of the deviation of phase from midactivity. In all cases, the index would decrease in size as the contribution of the exogenous component to a data set fell. The purification by categories approach was successful in proportion to the number of activity categories that was used, and as few as four categories produced a data set with significantly less masking than raw data. The method purification by intercepts was less successful unless the raw data had been "corrected" to reflect the direct effects of sleep that were independent of activity (a method to achieve this being produced). Use of this purification method with the corrected data then gave results that showed least exogenous influences. Both this method and the purification by categories method with 16 categories of activity gave evidence that the exogenous component no longer made a significant contribution to the purified data set. The results were not significantly influenced by assessing amplitude and phase of the circadian rhythm from crossover times rather than cosinor analysis. The relative merits of the different methods, as well as of other published methods, are compared briefly; it is concluded that several purification methods, of differing degrees of sophistication and ease of application to raw data, are of value in field studies and other circumstances in which constant routines are not possible or are ethically undesirable. It is also concluded that such methods are often somewhat limited insofar as they are based on pragmatic or biological, rather than mathematical, considerations, and so it is desirable to attempt to develop models based equally on mathematics and biology.
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Objectives: This study examined the hypothesis that alertness can be used to predict time-of-day effects on performance. Methods: For 6 or 7 days the volunteers (24, highly practiced young women) were required to retire to bed at 0000 and... more
Objectives: This study examined the hypothesis that alertness can be used to predict time-of-day effects on performance. Methods: For 6 or 7 days the volunteers (24, highly practiced young women) were required to retire to bed at 0000 and were awakened at 0800. A battery of mood and performance tests was completed every 2 hours while the women were awake; the result was 9 equally spaced measures per day. Measures of mood, serial reaction time, and memory scanning were recorded. Rectal temperature was recorded continuously. Results: After omitting the data from the first day to avoid any carry-over from the "first-night" effect on sleep, average time-of-day functions were calculated for each subject, for each variable, and were then z-transformed. Cross-correlations between the pooled time-of-day trends indicated that, while alertness was a reasonably good "predictor" of the simple perceptual-motor speed measures, it fared less well for some of the other measures. Two-way analyses of variance indicated that the time-of-day trend for all measures differed from that for alertness, although the magnitude of this difference varied substantially and, for some measures, was very largely due to the last reading of the day (0000). Conclusion: It is clear from these results that, while alertness may successfully "predict" variations in some measures of performance capability, and especially those of simple perceptual motor speed, care should be exercised in extrapolating to other performance measures.
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The Shiftwork Survey (SS) was introduced, along with the Standard Shiftwork Index (SSI), to provide a set of standardized self-report measures to be used in shiftwork research. However, beyond the initial assessment, no attempt has been... more
The Shiftwork Survey (SS) was introduced, along with the Standard Shiftwork Index (SSI), to provide a set of standardized self-report measures to be used in shiftwork research. However, beyond the initial assessment, no attempt has been made to examine the measurement properties of these scales in an independent sample of shiftworkers. Our goal, therefore, was to examine the measurement properties of these scales in an industrial sample of primarily male shiftworkers (N = 370). We found that all scales had acceptable reliabilities (alphas). The confirmatory factor analyses revealed that the chronic fatigue, coping, job satisfaction, and sleep scales are the weakest psychometrically, and the anxiety, personality (extraversion, neuroticism), general health, and physical health scales are the strongest psychometrically. Using item response theory analyses, we found that the scales overall are generally adequate measures of their underlying constructs, although many items should be altered or omitted. Our results, however, are limited by reliance on a single sample.
Research Interests: Psychology, Psychometrics, Fatigue, Medicine, Anxiety, and 15 moreHumans, Personality Assessment Inventory, Neuroticism, Pubmed, Confirmatory factor analysis, Male, Mathematical Computing, Middle Aged, Adult, Public health systems and services research, Reproducibility of Results, Health surveys, ANXIETY, Personality Inventory, and personnel staffing and scheduling
Research Interests: Nursing, Perception, Aging, Medicine, Humans, and 15 moreAge, Female, Male, Incidence, Aged, Prevalence, Middle Aged, Longitudinal Studies, Adult, Longitudinal Study, Age Factors, Cross sectional Study, Cross Sectional Studies, Occupational and environmental medicine, and personnel staffing and scheduling
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Research Interests: Occupational Health, Fatigue, Medicine, Humans, Circadian Rhythm, and 15 moreChronic Disease, Sleep, Attitude, Awareness, Clinical Sciences, Occupational, Adult, Public health systems and services research, Retrospective Studies, Shift Work, Morning, Indexation, Alertness, Occupational and environmental medicine, and personnel staffing and scheduling
Research Interests: Performance, Health, Comparative Research, Fatigue, Comparative Study, and 15 moreMedicine, Safety, Humans, Absenteeism, Psychological Wellbeing, Clinical Sciences, Physical Fitness, Family Relations, Occupational, Job Performance, Public health systems and services research, Shift Work, Occupations, Occupational and environmental medicine, and Personnel Turnover
Research Interests: Psychology, Cognitive Science, Animal Science, Rhythm, Biology, and 15 moreMedicine, Linear models, Humans, Circadian Rhythm, Lighting, Sleep, Oscillations, Body Temperature, Adult, Light Intensity, Controlled Environment Agriculture, Core temperature, Neurosciences, Phase Shift, and Phase Response Curve
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Research Interests: Performance, Health, Comparative Study, Medicine, Safety, and 15 moreHumans, Paradigm Shift, Male, Duration, Mental Disorders, Clinical Sciences, ENVIRONMENTAL AND OCCUPATIONAL HEALTH, Adult, Public health systems and services research, Analysis of Variance, Shift Work, Cardiovascular Diseases, Indexation, Alertness, and Occupational and environmental medicine
Research Interests: Nursing, Perception, Gerontology, Medicine, Humans, and 15 moreAge, Female, Male, Incidence, Prevalence, Middle Aged, Longitudinal Studies, Adult, Self Perception, Public health systems and services research, Longitudinal Study, Age Factors, Cross sectional Study, Cross Sectional Studies, and Occupational and environmental medicine
Research Interests: Psychology, Employment, Medicine, France, Biological Sciences, and 15 moreHumans, Female, Male, Aged, Middle Aged, Questionnaires, Longitudinal Studies, Adult, Longitudinal Study, Age Factors, Cross sectional Study, Cross Sectional Studies, Cohort Studies, Psychology and Cognitive Sciences, and Medical and Health Sciences
Research Interests: Chronobiology, Demography, Occupational Health, Risk, Fatigue, and 15 moreMedicine, Biological Sciences, Humans, Female, Male, Regression Analysis, Sleep, Middle Aged, Rest, Adult, Morning, Accident Prevention, Occupational Accidents, personnel staffing and scheduling, and Medical and Health Sciences
The effects on industrial shift workers of the timing of the changeover from the night to morning shift and of the length of the shift were examined. Two groups changed over at 6 a.m. and worked either 8-hr or 12-hr shift systems; the... more
The effects on industrial shift workers of the timing of the changeover from the night to morning shift and of the length of the shift were examined. Two groups changed over at 6 a.m. and worked either 8-hr or 12-hr shift systems; the other 2 groups changed over at 7 a.m., working either 8- or 12-hr systems. Night sleeps between consecutive shifts that started at 6 a.m. were shorter and more disrupted than those starting at 7 a.m. Day sleeps following night shifts that finished at 6 a.m. were longer and less disrupted than those finishing at 7 a.m. Early starts were associated with poorer psychological and physical health. These effects of changeover time are considered in relation to the circadian rhythms in sleep duration and propensity. Although several measures favored 12-hr shifts, physical health indicators appeared to favor 8-hr systems, especially in combination with late changeovers. However, the observed effects of shift length on chronic outcome measures are somewhat inconsistent with previous research findings.
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Objectives: This study examined the combined effects of shift length (8 versus 12 hours) and night-to-morning-shift changeover time (0600 versus 0700) on retrospective on-shift alertness ratings. Methods: An abridged version of the... more
Objectives: This study examined the combined effects of shift length (8 versus 12 hours) and night-to-morning-shift changeover time (0600 versus 0700) on retrospective on-shift alertness ratings. Methods: An abridged version of the Standard Shiftwork Index, which included retrospective alertness ratings, was completed by 4 groups of industrial shift workers. Two groups worked 8-hour shift systems and started their morning shifts at either 0600 or 0700; the other 2 groups worked 12-hour systems, starting their day shifts at either 0600 or 0700. Results: The 8-hour workers reported considerably higher levels of alertness in the afternoon, while the 12-hour workers were more alert than the 8-hour workers in the morning and at 2200. Workers who started their shift around 0600 were less alert during the morning than those who started around 0700. The data suggested that the combined effects of working 8-hour shifts and starting the morning shift at around 0600 have particularly deleterious effects upon alertness. Conclusions: Effects on alertness can be explained in terms of differences in elapsed time on duty, sleep duration, sleep disruption, and chronic fatigue. The findings of this study appear to contradict previous research demonstrating that the major deleterious effects of extended shifts and delayed changeovers upon alertness occur at night. However, it is acknowledged that the absence of a difference in alertness at night may have been due to floor effects. Nevertheless, the implications of the alertness ratings for performance and safety, particularly during the afternoon, should not be ignored.
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ObjectivesTo examine if a proactive recovery intervention for newly graduated registered nurses (RNs) could prevent the development of sleep problems, burn-out, fatigue or somatic symptoms.MethodsThe study was a randomised control trial... more
ObjectivesTo examine if a proactive recovery intervention for newly graduated registered nurses (RNs) could prevent the development of sleep problems, burn-out, fatigue or somatic symptoms.MethodsThe study was a randomised control trial with parallel design. Newly graduated RNs with less than 12 months’ work experience were eligible to participate. 461 RNs from 8 hospitals in Sweden were invited, of which 207 signed up. These were randomised to either intervention or control groups. After adjustments, 99 RNs were included in the intervention group (mean age 27.5 years, 84.7% women) and 108 in the control group (mean age 27.0 years, 90.7% women). 82 RNs in the intervention group attended a group-administered recovery programme, involving three group sessions with 2 weeks between each session, focusing on proactive strategies for sleep and recovery in relation to work stress and shift work. Effects on sleep, burn-out, fatigue and somatic symptoms were measured by questionnaires at bas...
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Research Interests: Sociology and Social Care
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... more
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 night workers fail to …
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IntroductionDepression-related mood disorders affect millions of people worldwide and contribute to substantial morbidity and disability, yet little is known about the effects of work scheduling on depression. This study used a large... more
IntroductionDepression-related mood disorders affect millions of people worldwide and contribute to substantial morbidity and disability, yet little is known about the effects of work scheduling on depression. This study used a large Swedish survey to prospectively examine the effects of work schedule on registry-based antidepressant prescriptions in females and males over a 2-year period.MethodsThe study was based on an approximately representative sample (n=3980 males, 4663 females) of gainfully employed participants in the Swedish Longitudinal Occupational Survey of Health. Sex-stratified analyses were conducted using logistic regression. For exposure, eight categories described work schedule in 2008: ‘regular days’ (three categories of night work history: none, ≤3 years, 4+ years), ‘night shift work’, ‘regular shift work (no nights)’, ‘rostered work (no nights)’, ‘flexible/non-regulated hours’ and ‘other’. For the primary outcome measure, all prescriptions coded N06A according t...
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Background Shift work may impact women more negatively than men due to the increased burden of coping with demanding work schedules while also undertaking more of the domestic chores, including childcare. Aims To examine whether the... more
Background Shift work may impact women more negatively than men due to the increased burden of coping with demanding work schedules while also undertaking more of the domestic chores, including childcare. Aims To examine whether the combination of shift working and caring for children affects the sleep, fatigue and work–family conflict experienced by women more than it affects men. Methods Using data from a survey of the Swedish working population, mixed linear regression models examined work schedule (daywork, shift work with nights, shift work without nights), gender and presence of children <13 years at home as predictors of sleep insufficiency, sleep disturbance, fatigue and work–family conflict, over up to three successive measurement occasions. Adjustments were made for age, education, full/part-time working and baseline year. Results In fully adjusted models (N = 8938), shift work was associated with insufficient sleep (P < 0.01), disturbed sleep (P < 0.01), fatigue ...
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Research Interests: Cognition, Medicine, France, Prospective studies, Humans, and 13 moreCircadian Rhythm, Female, Male, Cohort, Clinical Sciences, Middle Aged, Longitudinal Studies, Adult, Public health systems and services research, Shift Work, Cognition disorders, Occupational and environmental medicine, and Prospective Cohort Study
Research Interests: Psychology, Employment, Medicine, France, Biological Sciences, and 15 moreHumans, Female, Male, Aged, Middle Aged, Questionnaires, Longitudinal Studies, Adult, Longitudinal Study, Age Factors, Cross sectional Study, Cross Sectional Studies, Cohort Studies, Psychology and Cognitive Sciences, and Medical and Health Sciences
Research Interests: Psychology, Risk, Job Satisfaction, Health, Public Health, and 15 moreFatigue, Medicine, Humans, Female, Male, Physicians, Risk Factor, Questionnaires, Rest, Adult, Public health systems and services research, Occupational Diseases, Personal Satisfaction, Night Work, and personnel staffing and scheduling
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The study aimed to measure the effects of a 27-h &#39;day&#39; sleep-wake regime on actigraphic and subjective sleep variables, and to examine the relationships between these variables. Nine subjects spent 30 days and nights in... more
The study aimed to measure the effects of a 27-h &#39;day&#39; sleep-wake regime on actigraphic and subjective sleep variables, and to examine the relationships between these variables. Nine subjects spent 30 days and nights in the laboratory. After sleeping 8 h for each of 8 nights, the subjects had an imposed 27-h &#39;day&#39;, for 18 &#39;days&#39;, remaining in bed for 9 h on each sleep period. Sleep periods therefore started 3 h later each day, although subjects&#39; circadian rhythms stayed entrained to 24 h, because subjects were not isolated from the natural light-dark cycle. Time asleep, subjective sleep efficiency and subjective sleep quality, but not movement during sleep, were found to be significantly affected by time of going to bed. There were significant decreases in movement during recovery sleeps following each of two episodes of 26 h sleep deprivation. Over the study there were significant within-subject correlations between subjective sleep quality and subjective sleep efficiency (rav = 0.65), movement during sleep and subjective sleep efficiency (rav = -0.48), and movement during sleep and subjective sleep quality (rav = -0.26). We conclude that sleep movement, despite its low within- and between-subjects variability, is nevertheless a statistically reliable, but weak, indicator of subjective sleep efficiency and quality.
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Research Interests: Nursing, Perception, Aging, Medicine, Humans, and 15 moreAge, Female, Male, Incidence, Aged, Prevalence, Middle Aged, Longitudinal Studies, Adult, Longitudinal Study, Age Factors, Cross sectional Study, Cross Sectional Studies, Occupational and environmental medicine, and personnel staffing and scheduling
This paper starts by summarizing the development and refinement of the additive three-process model of alertness first published by Folkard and Åkerstedt in 1987. It reviews some of the successes that have been achieved by the model in... more
This paper starts by summarizing the development and refinement of the additive three-process model of alertness first published by Folkard and Åkerstedt in 1987. It reviews some of the successes that have been achieved by the model in not only predicting variations in subjective alertness on abnormal sleep-wake schedules but also in accounting for objective measures of sleep latency and duration. Nevertheless, predictions derived from the model concerning alertness on different shifts, and over successive night shifts, are difficult to reconcile with published data on accident risk. In light of this, we have examined two large sets of alertness ratings with a view to further refining the model and identifying additional factors that may influence alertness at any given point in time. Our results indicate that, at least for the range of sleep durations and wake-up times commonly found on rotating shift systems, we may assume the phase of the endogenous circadian component of alertne...
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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,... more
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 identified associations between shiftwork and metabolic syndrome, there is relatively little evidence to date of how the risk of developing it varies as a function of exposure to shiftwork. The current study seeks to confirm earlier findings of an association between shiftwork exposure and metabolic dysfunction, and to examine the impact of exposure duration, while adjusting for a number of covariates in the analyses. The analyses were based on data from VISAT, a study involving the measurement of physiological, behavioral, and subjective outcomes from 1757 participants, 989 being current or former shiftworkers. The sample comprised employed and retired wage earners, male and female, who were 32, 42, 52, and 62 yrs old. The first analysis sought to confirm previous findings of an association between exposure to shiftwork and the risk of developing metabolic syndrome. It indicated that participants who were or who had previously been shiftworkers (i.e., working schedules that involved rotating shifts; not being able to go to bed before midnight; having to get up before 05:00 h; or being prevented from sleeping during the night) were more likely to exhibit symptoms of metabolic syndrome, after adjusting for age, sex, socioeconomic status, smoking, alcohol intake, perceived stress, and sleep difficulty (odds ratio [OR] 1.78; 95% confidence interval [CI] 1.03-3.08). The results suggest the association between shiftwork and metabolic syndrome cannot be fully accounted for by either higher levels of strain or increased sleep difficulty among shiftworkers, although it remains a possibility that either one or both of these factors may have played a contributing role. The second analysis addressed the issue of duration of exposure to shiftwork. Participants with &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;10 yrs&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; experience of working rotating shifts were more likely to exhibit symptoms of metabolic syndrome than participants without exposure to shiftwork, i.e., dayworkers, even after adjusting for age and sex (OR 1.96; 95% CI 1.03-3.75). Thus, the current study confirms the association between shiftwork exposure and metabolic syndrome. It also provides new information regarding the time course of the development of the illness as function of exposure duration, although this was only examined in relation to rotating shiftwork. It is concluded that those responsible for monitoring workers&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; health should pay particular attention to indices of metabolic dysfunction in workers who have been exposed to shiftwork for &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;10 yrs.
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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... more
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 taken to reach peak, and fasting level. Circadian variations in meal tolerance were found for the area under the curve and largest increase, responses were greater (indicating poorer meal tolerance) in the evening than the morning. Fasting blood glucose exhibited diurnal variation although in the opposite direction to meal tolerance; levels were higher in the morning than the evening. Time taken to reach peak levels was not modulated by circadian rhythmicity. Estimates of the timing of poorest meal tolerance and the magnitude of this intolerance were computed for each subject. Individual differences in the magnitude of meal intolerance were found to influence hunger and self-reported calmness. Subjects with good tolerance had rhythms in both calmness and hunger, which were not found in those with poor tolerance. Subjects with good tolerance also tended to rate themselves as feeling more calm. These mood and hunger effects may result from differences in insulin resistance, which is hypothesized to underlie the circadian variations in meal tolerance.
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Research Interests: Performance, Health, Comparative Research, Fatigue, Comparative Study, and 15 moreMedicine, Safety, Humans, Absenteeism, Psychological Wellbeing, Clinical Sciences, Physical Fitness, Family Relations, Occupational, Job Performance, Public health systems and services research, Shift Work, Occupations, Occupational and environmental medicine, and Personnel Turnover
This study examined the hypothesis that alertness can be used to predict time-of-day effects on performance. For 6 or 7 days the volunteers (24, highly practiced young women) were required to retire to bed at 0000 and were awakened at... more
This study examined the hypothesis that alertness can be used to predict time-of-day effects on performance. For 6 or 7 days the volunteers (24, highly practiced young women) were required to retire to bed at 0000 and were awakened at 0800. A battery of mood and performance tests was completed every 2 hours while the women were awake; the result was 9 equally spaced measures per day. Measures of mood, serial reaction time, and memory scanning were recorded. Rectal temperature was recorded continuously. After omitting the data from the first day to avoid any carry-over from the "first-night" effect on sleep, average time-of-day functions were calculated for each subject, for each variable, and were then z-transformed. Cross-correlations between the pooled time-of-day trends indicated that, while alertness was a reasonably good "predictor" of the simple perceptual-motor speed measures, it fared less well for some of the other measures. Two-way analyses of variance ...
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Research Interests: Chronobiology, Occupational Health, Risk, Fatigue, Biological Sciences, and 15 moreHumans, Female, Male, Regression Analysis, Sleep, Workload, Middle Aged, Rest, Adult, Time Factors, Wounds and Injuries, Accident Prevention, Occupational Accidents, personnel staffing and scheduling, and Medical and Health Sciences
Having to work working outside the normal ‘9-5’ (e.g. due to shift work, long weekly work hours or flexible working) can affect men and women differently. For example, women’s health is often reported to be more negatively affected by... more
Having to work working outside the normal ‘9-5’ (e.g. due to shift work, long weekly work hours or flexible working) can affect men and women differently. For example, women’s health is often reported to be more negatively affected by shift working than men, although the evidence of such a gender divide is mixed. Similarly, while some studies suggest that women benefit more from high work-time control, others report women experiencing negative effects of greater work-time control. In reviewing the evidence, we will examine whether women and men have different experiences of working different types of non-standard work hours, and consider what factors might account for those gender differences.
Research Interests: Psychology and Well Being
Research Interests: Engineering and Medicine
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E-mail philip.tucker@su.se Stress Research Institute is a knowledge centre in the area of stress and health. The Institute is part of the Faculty of Social Science, Stockholm University, Sweden and conducts basic and applied research on... more
E-mail philip.tucker@su.se Stress Research Institute is a knowledge centre in the area of stress and health. The Institute is part of the Faculty of Social Science, Stockholm University, Sweden and conducts basic and applied research on multidisciplinary and interdisciplinary methodological approaches. E-mail info@stressforskning.su.se Website www.stressresearch.se Background & Aim Shiftwork is associated with increased risk of gastro-intestinal problems, metabolic disorders, cardiovascular disease, musculo-skeletal disorders, mental illhealth and chronic sleep disturbance. We aim to analyze data from the Swedish Longitudinal Occupational Survey of Health (SLOSH) and the Finnish Public Sector Study (FPSS) to prospectively examine associations between shiftwork and the purchase of drugs associated with these health complaints.
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Research Interests: Chronobiology, Biological Sciences, Prospective studies, Humans, Work, and 14 moreCircadian Rhythm, Female, Male, Young Adult, Sleep, Risk factors, Middle Aged, Adult, Risk Factors, Logistic Models, Occupational Accidents, Cohort Studies, Medical and Health Sciences, and Sleep initiation and maintenance disorders
Quick returns (intervals of <11 h between the end of one shift and the start of the next) are associated with short sleeps and fatigue on the subsequent shift. Recent evidence suggests that shift workers regard quick returns as being... more
Quick returns (intervals of <11 h between the end of one shift and the start of the next) are associated with short sleeps and fatigue on the subsequent shift. Recent evidence suggests that shift workers regard quick returns as being more problematic than night work. The current study explored quick returns and night work in terms of their impact on sleep, unwinding, recovery, exhaustion, satisfaction with work hours and work-family interference. Data from the 2006 cohort of Swedish nursing students within the national Longitudinal Analysis of Nursing Education (LANE) study were analysed (N = 1459). Respondents completed a questionnaire prior to graduation (response rate 69.2%) and 3 years after graduation (65.9%). The analyses examined associations between frequency of quick returns and night work and measures taken in year three, while adjusting for confounding factors (in year three and prior graduation). Frequency of quick returns was a significant predictor of poor sleep qua...
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Past research has often neglected the sub-dimensions of work time control (WTC). Moreover, differences in levels of WTC with respect to work and demographic characteristics have not yet been examined in a representative sample. We... more
Past research has often neglected the sub-dimensions of work time control (WTC). Moreover, differences in levels of WTC with respect to work and demographic characteristics have not yet been examined in a representative sample. We investigated these matters in a recent sample of the Swedish working population. The study was based on the 2014 data collection of the Swedish Longitudinal Occupational Survey of Health. We assessed the structure of the WTC measure using exploratory and confirmatory factor analysis. Differences in WTC by work and demographic characteristics were examined with independent samplet-tests, one-way ANOVAs and gender-stratified logistic regressions. Best model fit was found for a two-factor structure that distinguished between control over daily hours and control over time off (root mean square error of approximation = 0.06; 95% CI 0.04 to 0.09; Comparative Fit Index (CFI) = 0.99). Women, shift and public-sector workers reported lower control in relation to bot...
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As with many forms of flexible working, Annualized Hours (AH) systems offer potential benefits to both the employer and the employee. However, the flexibility requirements of employers and employees often conflict. Therefore, when a large... more
As with many forms of flexible working, Annualized Hours (AH) systems offer potential benefits to both the employer and the employee. However, the flexibility requirements of employers and employees often conflict. Therefore, when a large food manufacturing organization decided to redesign its AH system, it employed an independent consultancy to act as neutral third party. The consultancy provided technical expertise and assistance in developing an AH system that optimised productivity and was acceptable to the workforce. Data are presented, obtained from focus groups conducted throughout the organization, describing some of the potential difficulties of implementing an AH system. Drawing upon these data, a number of new AH systems were proposed and modelled using specialist software tools. The design process is described, together with the advantages and difficulties associated with use of the software tools. It is concluded that the key elements in the process of designing AH systems are centred around issues of trust and communication; the involvement of a broad range of interested parties, through a process of carefully managed group facilitation; and the need for adequate technical support in the development and evaluation of AH systems.
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The Shiftwork Survey (SS) was introduced, along with the Standard Shiftwork Index (SSI), to provide a set of standardized self-report measures to be used in shiftwork research. However, beyond the initial assessment, no attempt has been... more
The Shiftwork Survey (SS) was introduced, along with the Standard Shiftwork Index (SSI), to provide a set of standardized self-report measures to be used in shiftwork research. However, beyond the initial assessment, no attempt has been made to examine the measurement properties of these scales in an independent sample of shiftworkers. Our goal, therefore, was to examine the measurement properties of these scales in an industrial sample of primarily male shiftworkers (N = 370). We found that all scales had acceptable reliabilities (alphas). The confirmatory factor analyses revealed that the chronic fatigue, coping, job satisfaction, and sleep scales are the weakest psychometrically, and the anxiety, personality (extraversion, neuroticism), general health, and physical health scales are the strongest psychometrically. Using item response theory analyses, we found that the scales overall are generally adequate measures of their underlying constructs, although many items should be alte...
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As with many forms of flexible working, Annualized Hours (AH) systems offer potential benefits to both the employer and the employee. However, the flexibility requirements of employers and employees often conflict. Therefore, when a large... more
As with many forms of flexible working, Annualized Hours (AH) systems offer potential benefits to both the employer and the employee. However, the flexibility requirements of employers and employees often conflict. Therefore, when a large food manufacturing organization decided to redesign its AH system, it employed an independent consultancy to act as neutral third party. The consultancy provided technical expertise and assistance in developing an AH system that optimised productivity and was acceptable to the workforce. Data are presented, obtained from focus groups conducted throughout the organization, describing some of the potential difficulties of implementing an AH system. Drawing upon these data, a number of new AH systems were proposed and modelled using specialist software tools. The design process is described, together with the advantages and difficulties associated with use of the software tools. It is concluded that the key elements in the process of designing AH syst...
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... Hanled, Jaradat and Easa, 1998 reported a study of nlinibus drivers in Jordan, in which they found that drivers who took regular rest breaks ... effectively addressed when the individual is able to adjust the tinling of their rest to... more
... Hanled, Jaradat and Easa, 1998 reported a study of nlinibus drivers in Jordan, in which they found that drivers who took regular rest breaks ... effectively addressed when the individual is able to adjust the tinling of their rest to coincide with periods of fatigue (eg Halin, 1989), while ...
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The authors examined how associations between work hours and self-reported health are moderated by the reasons given for working overtime, by schedule autonomy, and by the degree of social support experienced, in a survey of 372 train... more
The authors examined how associations between work hours and self-reported health are moderated by the reasons given for working overtime, by schedule autonomy, and by the degree of social support experienced, in a survey of 372 train drivers. Respondents who lacked both schedule autonomy and social support demonstrated positive associations between the number of hours worked per week and frequency of physical health symptoms. Conversely, negative associations were observed among respondents reporting low schedule autonomy together with high social support. There were no such interactions in the analyses of fatigue and psychological health outcomes. The findings are discussed in terms of the fit between an individual&amp;amp;amp;amp;amp;amp;#39;s actual and desired work hours. The problems of identifying appropriate limits for work hours are highlighted.
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The effects on industrial shift workers of the timing of the changeover from the night to morning shift and of the length of the shift were examined. Two groups changed over at 6 a.m. and worked either 8-hr or 12-hr shift systems; the... more
The effects on industrial shift workers of the timing of the changeover from the night to morning shift and of the length of the shift were examined. Two groups changed over at 6 a.m. and worked either 8-hr or 12-hr shift systems; the other 2 groups changed over at 7 a.m., working either 8- or 12-hr systems. Night sleeps between consecutive shifts that started at 6 a.m. were shorter and more disrupted than those starting at 7 a.m. Day sleeps following night shifts that finished at 6 a.m. were longer and less disrupted than those finishing at 7 a.m. Early starts were associated with poorer psychological and physical health. These effects of changeover time are considered in relation to the circadian rhythms in sleep duration and propensity. Although several measures favored 12-hr shifts, physical health indicators appeared to favor 8-hr systems, especially in combination with late changeovers. However, the observed effects of shift length on chronic outcome measures are somewhat inconsistent with previous research findings.
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... Philip Tucker and Dylan M. JoNEsf School of Psychology, University of Wales, College of Cardiff, PO Box 901, Cathays Park, Cardiff ... Nicholson (1985) notes that amongst infrequent users of an experimental voice store-and-forward... more
... Philip Tucker and Dylan M. JoNEsf School of Psychology, University of Wales, College of Cardiff, PO Box 901, Cathays Park, Cardiff ... Nicholson (1985) notes that amongst infrequent users of an experimental voice store-and-forward system, opinions were expressed concerning ...
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Speech, as a medium for communicating with computers, has several potential advantages, and its introduction may have far‐reaching implications for the evolution of information technology. Yet, despite the availability of speech I/O... more
Speech, as a medium for communicating with computers, has several potential advantages, and its introduction may have far‐reaching implications for the evolution of information technology. Yet, despite the availability of speech I/O devices over the past few years, their introduction into day‐today use has been relatively slow. A human factors perspective helps to explain the predominance of the visual/manual interface, and the reasons for its preference over speech. This view reflects fundamental differences between the two modes of communication. However, human factors also suggest that much can be done to improve the usability of speech systems. Broad guidelines for the use of speech‐output devices are detailed, and include criteria for the assignment of output either to the visual or auditory channel. The human factors of synthetic speech are discussed, in terms of enhancing both its intelligibility and its acceptability to users. Performance measures of automatic speech recognition (ASR) technology must account for the sensitivity of such devices to extraneous factors. A description of contemporary ASR technology serves as a basis for the explanation of this sensitivity, and of the limited performance of such devices. Guidelines for the implementation of ASR technology are described that address both user behavior and the interaction of the device with its environment. Modality effects upon user behavior in a man‐machine dialogue are described.
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There were 15 healthy female subjects, differing in their position on the &quot;morningness-eveningness&quot; scale, studied for 7 consecutive days, first while living a sedentary lifestyle and sleeping between midnight and 08:00... more
There were 15 healthy female subjects, differing in their position on the &quot;morningness-eveningness&quot; scale, studied for 7 consecutive days, first while living a sedentary lifestyle and sleeping between midnight and 08:00 and then while undergoing a &quot;constant routine.&quot; Rectal temperature was measured at regular intervals throughout this time, and the results were subjected to cosinor analysis both before and after &quot;purification&quot; for the effects of physical activity. Results showed that there was a phase difference in the circadian rhythm of core temperature that was associated with the morningness score, with calculations that &quot;morning types&quot; would be phased earlier than &quot;evening types&quot; by up to about 3 h. This difference in phase (which was also statistically significant when the group was divided by a median split into a &quot;morning group&quot; and an &quot;evening group&quot;) could not be attributed to effects of waking activity and existed in spite of the subjects keeping the same sleep-wake schedule. Moreover, it persisted when the subjects&#39; data had been purified and when the data were obtained from the constant routine. That is, there was an endogenous component to this difference in phase of the core temperature. The morning group also showed a greater fall of core temperature during sleep; this was assessed in two ways, the main one being a comparison of constant routine and nychthemeral data sets after correction for any effects of activity. Even though the morning group was sleeping at a later phase of their circadian temperature rhythm than was the evening group, neither group showed a fall of temperature due to sleep that varied with time elapsed since the temperature acrophase. It is concluded that another factor that differs between morning and evening types is responsible for this difference.
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The activity records of five groups of healthy or ill subjects have been measured for 4-26 days by an accelerometer placed on the nondominant wrist. These data, together with a record of times retiring to/rising from bed, have been used... more
The activity records of five groups of healthy or ill subjects have been measured for 4-26 days by an accelerometer placed on the nondominant wrist. These data, together with a record of times retiring to/rising from bed, have been used to produce a series of dichotomy indices for comparing the amounts of activity when in bed and out of bed. Reliable differences between individuals were found, with healthy subjects showing a greater degree of dichotomy than one subject with delayed sleep phase syndrome or three subjects with colorectal cancer. The method is convenient for extended data collection and offers the possibility of describing an individual&#39;s activity profile in a variety of circumstances.
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ABSTRACT Nine healthy females were studied about the time of the spring equinox, while living in student accommodation and aware of the passage of solar time. After 7 control days, during which a conventional lifestyle was lived, subjects... more
ABSTRACT Nine healthy females were studied about the time of the spring equinox, while living in student accommodation and aware of the passage of solar time. After 7 control days, during which a conventional lifestyle was lived, subjects underwent a 24-h ‘constant routine’, followed by 17 ‘days’ on a 27-h ‘day’ (9 h sleep and 18 h wake). Throughout the experiment, regular recordings of (non-dominant) wrist activity (every 30 s) and rectal temperature (every 6 min) were made. Only the control and 27-h (experimental) ‘days’ have been analysed in the present report. From each subject, 24-h profiles of raw temperature (consisting of 240 points) were obtained: one (control days), by averaging the control days; the other (experimental days), by conflating 16 consecutive 27-h ‘days’. Activity data were first collected into 240 points by summing them over 6-min intervals; they were then converted into three data sets (each of 240 points) for control and, separately, for experimental days. These data sets were summed activities in the previous 18 min (A18), summed activity over the previous 18–30 min (A30), and summed activity over the previous 30–42 min (A42). The raw temperature data sets for control and experimental days were sepa-rately analysed by ANCOVA using two time-of-day factors: ‘hours’ (24 levels) and ‘six-minute-intervals’ (10 levels). The covariate was the three activity data sets; in order to make the analysis more versatile, a cubic polynomial model was used, with a linear, quadratic and cubic term for each of these activity data sets. Moreover, the effects of activity upon core temperature were separately assessed for four 6-h sections of the 24-h profile, centred on its low, rising, high and falling phases. The main results were as follows: 1. All three activity data sets made significant contributions to the model, but that by the A30 data set was the most powerful of the three. This supports the use of activity files covering the previous 30 min in other ‘purification’ methods. 2. Although the linear term was the one that was significant most frequently, quadratic and (negative) cubic terms were also present on several occasions. This result indicates that the effect of activity upon core temperature can be approximated by a linear function (as has been done in other ‘purification’ models), but that, with wider ranges of activity, a sigmoid curve would be more accurate, indicative of the process of thermoregulation. 3. During the experimental days, the effect of activity upon temperature was greater in the rising than the falling temperature phase, and greater in the low than in the high phase. These results are predicted from current understanding of the circadian rhythm of thermoregulation. 4. During control days, the effects of activity were more complex, probably due to the factors that were present at some, but not all, phases — factors such as sleep, meals, changes in posture, lighting, and so on. 5. The ANCOVA also enabled the temperature profiles, corrected for the effects of activity (and, therefore, to be considered as ‘purified’), to be displayed. We conclude that the use of ANCOVA to tackle the problem of ‘purifying’ raw temperature data is a promising one. So far, it has produced results that accord with those from other ‘purification’ methods and with predictions based on our current understanding of the circadian rhythm of thermoregulation.
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The activity records of five groups of healthy or ill subjects have been measured for 4-26 days by an accelerometer placed on the nondominant wrist. These data, together with a record of times retiring to/rising from bed, have been used... more
The activity records of five groups of healthy or ill subjects have been measured for 4-26 days by an accelerometer placed on the nondominant wrist. These data, together with a record of times retiring to/rising from bed, have been used to produce a series of dichotomy indices for comparing the amounts of activity when in bed and out of bed. Reliable differences between individuals were found, with healthy subjects showing a greater degree of dichotomy than one subject with delayed sleep phase syndrome or three subjects with colorectal cancer. The method is convenient for extended data collection and offers the possibility of describing an individual&#39;s activity profile in a variety of circumstances.
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OBJECTIVES: This study examined the combined effects of shift length (8 versus 12 hours) and night-to-morning-shift changeover time (0600 versus 0700) on retrospective on-shift alertness ratings. METHODS: An abridged version of the... more
OBJECTIVES: This study examined the combined effects of shift length (8 versus 12 hours) and night-to-morning-shift changeover time (0600 versus 0700) on retrospective on-shift alertness ratings. METHODS: An abridged version of the Standard Shiftwork Index, which ...
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OBJECTIVES: The generally agreed view is that there is no ideal shift system, and that most systems will have both advantages and disadvantages. As such, attention has been placed on trying to identify good and bad features of shift... more
OBJECTIVES: The generally agreed view is that there is no ideal shift system, and that most systems will have both advantages and disadvantages. As such, attention has been placed on trying to identify good and bad features of shift systems, with a view to minimising the ...
Research Interests: Performance, Health, Comparative Study, Safety, Humans, and 14 moreSleep disorders, Male, Duration, Vigilance, Mental Disorders, Clinical Sciences, Wakefulness, ENVIRONMENTAL AND OCCUPATIONAL HEALTH, Adult, Public health systems and services research, Analysis of Variance, Cardiovascular Diseases, Indexation, and Occupational and environmental medicine
OBJECTIVES: The generally agreed view is that there is no ideal shift system, and that most systems will have both advantages and disadvantages. As such, attention has been placed on trying to identify good and bad features of shift... more
OBJECTIVES: The generally agreed view is that there is no ideal shift system, and that most systems will have both advantages and disadvantages. As such, attention has been placed on trying to identify good and bad features of shift systems, with a view to minimising the ...
Research Interests: Performance, Health, Comparative Study, Safety, Humans, and 14 moreSleep disorders, Male, Duration, Vigilance, Mental Disorders, Clinical Sciences, Wakefulness, ENVIRONMENTAL AND OCCUPATIONAL HEALTH, Adult, Public health systems and services research, Analysis of Variance, Cardiovascular Diseases, Indexation, and Occupational and environmental medicine
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Research Interests: Comparative Research, Fatigue, Safety, Humans, Absenteeism, and 13 moreSleep, Psychological Wellbeing, Clinical Sciences, Physical Fitness, Family Relations, Occupational, Job Performance, Sickness Absence from Work, Public health systems and services research, Time Factors, Occupations, Occupational and environmental medicine, and Personnel Turnover
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Employee control over work times has been associated with favorable psychosocial and health-related outcomes, but the evidence regarding sleep quality remains inconclusive. We examined cross-sectional and prospective associations between... more
Employee control over work times has been associated with favorable psychosocial and health-related outcomes, but the evidence regarding sleep quality remains inconclusive. We examined cross-sectional and prospective associations between work time control and sleep disturbances in a large working population, taking into account total hours worked. The data were from a full-panel longitudinal cohort study of Finnish public sector employees who responded to questions on work time control and sleep disturbances in years 2000-2001, 2004-2005, 2008-2009, and 2012. The analysis of cross-sectional associations was based on 129,286 person measurements from 68,089 participants (77% women) aged 17-73 years (mean 43.1). Data from 16,503 participants were used in the longitudinal analysis. Log-binomial regression analysis with the generalized estimating equations method was used. Consistently in both cross-sectional and longitudinal models, less control over work time was associated with greater sleep disturbances in the total population and among those working normal 40-hour weeks. Among participants working more than 40 hours a week, work time that was both very high (cross-sectional prevalence ratio compared to intermediate work time control [PR] 1.32, 95% confidence interval [CI] 1.05-1.65) and very low (PR 1.23, 95% CI 1.08-1.39) was associated with sleep disturbances, after adjustment for potential confounding factors. These data suggest that having few opportunities to influence the duration and positioning of work time may increase the risk of sleep disturbances among employees. For persons working long hours, very high levels of control over working times were also associated with increased risk of sleep disturbances. Salo P, Ala-Mursula L, Rod NH, Tucker P, Pentti J, Kivimäki M, Vahtera J. Work time control and sleep disturbances: prospective cohort study of Finnish public sector employees.