A predictive model of work-related fatigue based on hours-of-work

RESEARCH over several decades has implicated shiftwork as a major cause of work-·related fatigue and decreased health and safety. However, discriminating between different rosters in terms of fatigue has been difficult. This is partially due to the large number of different rosters currently worked as well as the significant costs associated with laboratory-based roster assessments. Due to difficulties with traditional laboratory-based methods of modelling rosters, it is the authors' aim to develop a quantitative approach based only on the timing and duration of work periods. The potential applications of quantitative fatigue modelling in monitoring health and safety outcomes are also discussed. Specific examples are given for quantifying fatigue in road transport. In conclusion, this model provides a simple, straightforward approach to quantifying fatigue. It also enables organisations to model the relationship between hours of work and health and safety outcomes or to model the implications of proposed roster changes

At home and away : measuring the sleep of Australian truck drivers

The causes of fatigue in truck drivers related to work hours have been studied extensively and are reasonably well understood. However, much less is known about how rest opportunities can be structured to optimise recovery from fatigue. The nature of the road transport industry often requires that rest be taken in various locations. New investigation in this area, focusing on sleep obtained in truck cabs and other non-home environments is critically important to complement existing understanding. This study examined sleep at home and in truck cabs, in truck drivers who were actively working during the time of the study. Thirty-seven male drivers aged between 24 and 63 years (age: 48.7 ± 9.0 years; mean ± SD) wore activity monitors (also known as ‘sleep watches’) and completed work and sleep diaries for a period of 21 days, recording their subjective fatigue levels before, during and after work shifts, and before and after sleep periods. They also self-rated their sleep quality and noted the number of times they woke during sleep periods. Analyses focused on home versus in-truck sleep periods. The subjective data suggested that a greater quantity (P < .001) and quality (P < .05) of sleep was obtained at home than in the truck, and that sleeping at home more effectively reduced fatigue levels (P < .001). The objective data showed trends towards longer sleep length at home, but other variables, including total sleep per 24 h and sleep quality, showed no significant differences. This study demonstrates that measuring sleep quantity and quality in operational road transport environments is feasible. The findings caution against over-reliance on laboratory and simulator studies since there are critical aspects of the operating environment that cannot be validly studied in artificially controlled settings. This study is unique in its direct examination of sleep quantity and quality in truck drivers sleeping at home and away from home

A predictive model of work-related fatigue based on hours-of-work

RESEARCH over several decades has implicated shiftwork as a major cause of work-·related fatigue and decreased health and safety. However, discriminating between different rosters in terms of fatigue has been difficult. This is partially due to the large number of different rosters currently worked as well as the significant costs associated with laboratory-based roster assessments. Due to difficulties with traditional laboratory-based methods of modelling rosters, it is the authors' aim to develop a quantitative approach based only on the timing and duration of work periods. The potential applications of quantitative fatigue modelling in monitoring health and safety outcomes are also discussed. Specific examples are given for quantifying fatigue in road transport. In conclusion, this model provides a simple, straightforward approach to quantifying fatigue. It also enables organisations to model the relationship between hours of work and health and safety outcomes or to model the implications of proposed roster changes

Introduction : aging and the multifaceted influences on adaptation to working time

This special issue of Chronobiology International presents a selection of papers originally delivered at the 18th International Symposium on Shift Work and Working Time, held at Yeppoon, Australia, in August 2007. The key theme of the symposium was “Aging and Working Time: Creating Safe Environments.” Older workers are widely believed to experience greater difficulty than younger workers adapting to shift work and irregular work schedules. However, while the three reviews of age effects published here (Costa & Di Milia, 2008; Folkard, 2008b; Gander & Signal, 2008) identify evidence that older workers do indeed adapt less well, they also demonstrate that much more research is urgently required. The remaining papers address various aspects of the impact of work schedules on health, safety, sleep, and performance. They can be divided into three broad categories: circadian and other periodic factors; sleep, sleepiness, and fatigue; and other aspects of health and adjustment. This collection of papers showcases the best of contemporary research on the safety and health effects of working hours, continuing the tradition established by the two previous issues of the journal devoted to earlier symposia on shift work and working time

The relationship between transpiration and nutrient uptake in wheat changes under elevated atmospheric CO2

The impact of elevated [CO2] (e[CO2]) on crops often includes a decrease in their nutrient concentrations where reduced transpiration-driven mass flow of nutrients has been suggested to play a role. We used two independent approaches, a free-air CO2 enrichment (FACE) experiment in the South Eastern wheat belt of Australia and a simulation study employing the agricultural production systems simulator (APSIM), to show that transpiration (mm) and nutrient uptake (g m−2) of nitrogen (N), potassium (K), sulfur (S), calcium (Ca), magnesium (Mg) and manganese (Mn) in wheat are correlated under e[CO2], but that nutrient uptake per unit water transpired is higher under e[CO2] than under ambient [CO2] (a[CO2]). This result suggests that transpiration-driven mass flow of nutrients contributes to decreases in nutrient concentrations under e[CO2], but cannot solely explain the overall decline. © 2017 Scandinavian Plant Physiology Societ

Risk thresholds for alcohol consumption: combined analysis of individual-participant data for 599 912 current drinkers in 83 prospective studies.

BACKGROUND: Low-risk limits recommended for alcohol consumption vary substantially across different national guidelines. To define thresholds associated with lowest risk for all-cause mortality and cardiovascular disease, we studied individual-participant data from 599 912 current drinkers without previous cardiovascular disease. METHODS: We did a combined analysis of individual-participant data from three large-scale data sources in 19 high-income countries (the Emerging Risk Factors Collaboration, EPIC-CVD, and the UK Biobank). We characterised dose-response associations and calculated hazard ratios (HRs) per 100 g per week of alcohol (12·5 units per week) across 83 prospective studies, adjusting at least for study or centre, age, sex, smoking, and diabetes. To be eligible for the analysis, participants had to have information recorded about their alcohol consumption amount and status (ie, non-drinker vs current drinker), plus age, sex, history of diabetes and smoking status, at least 1 year of follow-up after baseline, and no baseline history of cardiovascular disease. The main analyses focused on current drinkers, whose baseline alcohol consumption was categorised into eight predefined groups according to the amount in grams consumed per week. We assessed alcohol consumption in relation to all-cause mortality, total cardiovascular disease, and several cardiovascular disease subtypes. We corrected HRs for estimated long-term variability in alcohol consumption using 152 640 serial alcohol assessments obtained some years apart (median interval 5·6 years [5th-95th percentile 1·04-13·5]) from 71 011 participants from 37 studies. FINDINGS: In the 599 912 current drinkers included in the analysis, we recorded 40 310 deaths and 39 018 incident cardiovascular disease events during 5·4 million person-years of follow-up. For all-cause mortality, we recorded a positive and curvilinear association with the level of alcohol consumption, with the minimum mortality risk around or below 100 g per week. Alcohol consumption was roughly linearly associated with a higher risk of stroke (HR per 100 g per week higher consumption 1·14, 95% CI, 1·10-1·17), coronary disease excluding myocardial infarction (1·06, 1·00-1·11), heart failure (1·09, 1·03-1·15), fatal hypertensive disease (1·24, 1·15-1·33); and fatal aortic aneurysm (1·15, 1·03-1·28). By contrast, increased alcohol consumption was log-linearly associated with a lower risk of myocardial infarction (HR 0·94, 0·91-0·97). In comparison to those who reported drinking >0-≤100 g per week, those who reported drinking >100-≤200 g per week, >200-≤350 g per week, or >350 g per week had lower life expectancy at age 40 years of approximately 6 months, 1-2 years, or 4-5 years, respectively. INTERPRETATION: In current drinkers of alcohol in high-income countries, the threshold for lowest risk of all-cause mortality was about 100 g/week. For cardiovascular disease subtypes other than myocardial infarction, there were no clear risk thresholds below which lower alcohol consumption stopped being associated with lower disease risk. These data support limits for alcohol consumption that are lower than those recommended in most current guidelines. FUNDING: UK Medical Research Council, British Heart Foundation, National Institute for Health Research, European Union Framework 7, and European Research Council

Risk thresholds for alcohol consumption: combined analysis of individual-participant data for 599 912 current drinkers in 83 prospective studies.

BACKGROUND: Low-risk limits recommended for alcohol consumption vary substantially across different national guidelines. To define thresholds associated with lowest risk for all-cause mortality and cardiovascular disease, we studied individual-participant data from 599 912 current drinkers without previous cardiovascular disease. METHODS: We did a combined analysis of individual-participant data from three large-scale data sources in 19 high-income countries (the Emerging Risk Factors Collaboration, EPIC-CVD, and the UK Biobank). We characterised dose-response associations and calculated hazard ratios (HRs) per 100 g per week of alcohol (12·5 units per week) across 83 prospective studies, adjusting at least for study or centre, age, sex, smoking, and diabetes. To be eligible for the analysis, participants had to have information recorded about their alcohol consumption amount and status (ie, non-drinker vs current drinker), plus age, sex, history of diabetes and smoking status, at least 1 year of follow-up after baseline, and no baseline history of cardiovascular disease. The main analyses focused on current drinkers, whose baseline alcohol consumption was categorised into eight predefined groups according to the amount in grams consumed per week. We assessed alcohol consumption in relation to all-cause mortality, total cardiovascular disease, and several cardiovascular disease subtypes. We corrected HRs for estimated long-term variability in alcohol consumption using 152 640 serial alcohol assessments obtained some years apart (median interval 5·6 years [5th-95th percentile 1·04-13·5]) from 71 011 participants from 37 studies. FINDINGS: In the 599 912 current drinkers included in the analysis, we recorded 40 310 deaths and 39 018 incident cardiovascular disease events during 5·4 million person-years of follow-up. For all-cause mortality, we recorded a positive and curvilinear association with the level of alcohol consumption, with the minimum mortality risk around or below 100 g per week. Alcohol consumption was roughly linearly associated with a higher risk of stroke (HR per 100 g per week higher consumption 1·14, 95% CI, 1·10-1·17), coronary disease excluding myocardial infarction (1·06, 1·00-1·11), heart failure (1·09, 1·03-1·15), fatal hypertensive disease (1·24, 1·15-1·33); and fatal aortic aneurysm (1·15, 1·03-1·28). By contrast, increased alcohol consumption was log-linearly associated with a lower risk of myocardial infarction (HR 0·94, 0·91-0·97). In comparison to those who reported drinking >0-≤100 g per week, those who reported drinking >100-≤200 g per week, >200-≤350 g per week, or >350 g per week had lower life expectancy at age 40 years of approximately 6 months, 1-2 years, or 4-5 years, respectively. INTERPRETATION: In current drinkers of alcohol in high-income countries, the threshold for lowest risk of all-cause mortality was about 100 g/week. For cardiovascular disease subtypes other than myocardial infarction, there were no clear risk thresholds below which lower alcohol consumption stopped being associated with lower disease risk. These data support limits for alcohol consumption that are lower than those recommended in most current guidelines. FUNDING: UK Medical Research Council, British Heart Foundation, National Institute for Health Research, European Union Framework 7, and European Research Council