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A substantial body of literature indicates that shift workers have a significantly higher risk of workplace accidents and injuries, compared to workers in regular daytime schedules. This can be attributed to work during nights which require workers to stay awake during normal sleeping hours and sleep during natural waking hours, leading to circadian desynchronization, sleep disruption and cognitive impairment. A fatigue-risk trajectory model developed by Dawson and McCulloch has been used to describe the series of events which may precede fatigue-related incidents. This includes insufficient sleep opportunities, impaired sleep, fatigue-behavioral symptoms, and fatigue-related errors. The purpose of this paper is to provide examples of control measures along each level of the fatigue-risk trajectory, which include: (i) work scheduling strategies to include breaks for adequate sleep opportunities; (ii) training and educational programs to help workers make best use of recovery times for quality sleep; (iii) fatigue-detection devices to alert workers and safety managers of fatigue-related behaviors and errors. A brief introduction to Fatigue-Risk Management systems is also included as a long-term sustainable strategy to maintain shift worker health and safety. The key statements in this paper represent a consensus among the Working Time Society regarding a multi-level approach to managing occupational sleep-related fatigue.

The purpose of this study was to characterize the recovery pattern of sleep following simulated, four successive night shifts in ten healthy men (22.9 + or - 3.2 yr). Poor sleep was defined as sleep efficiency of 80% or lower as determined actigraphically. The results showed that four (rapid, slow, pseudo, and incomplete) patterns of sleep recovery were observed over three recovery sleep periods. The rapid and slow recovery pattern represented immediate and slow return to baseline level prior to the nightshifts, respectively. The pseudo recovery pattern demonstrated poor sleep at the 3rd recovery sleep period, despite transient recovery at the 2nd sleep period. The incomplete recovery pattern was characterized by consistently poorer sleep during the entire recovery period. The correlation analysis indicated that sleep habits (bed time and variation of wake time) prior to the experiment were significantly related to the recovery patterns, rather than performance and alertness during the night shifts.

There are considerable individual differences in cognitive performance deficits resulting from extended work hours and shift work schedules. Recent progress in sleep and performance research has yielded new insights into the causes and consequences of these individual differences. Neurobiological processes of sleep/wake regulation underlie trait individual variability in vulnerability to performance impairment due to sleep loss. Trait vulnerability to sleep loss is observed in the laboratory and in the work environment, even in occupational settings where (self-)selection pressures are high. In general, individuals do not seem to accurately assess the magnitude of their own vulnerability. Methods for identifying workers who are most at risk of sleep loss-related errors and accidents would therefore be helpful to target fatigue countermeasure interventions at those needing them most. As yet, no reliable predictors of vulnerability to sleep loss have been identified, although candidate genetic predictors have been proposed. However, a Bayesian forecasting technique based on closed-loop feedback of measured performance has been developed for individualized prediction of future performance impairment during ongoing operations. Judiciously selecting or monitoring individuals in specific tasks or occupations, within legally and ethically acceptable boundaries, has the potential to improve operational performance and productivity, reduce errors and accidents, and save lives. Trait individual variability in responses to sleep loss represents a major complication in the application of one-size-fits-all hours of service regulations--favoring instead modern fatigue risk management strategies, because these allow flexibility to account for individual vulnerability or resilience to the performance consequences of extended work hours and shift work schedules.

The aim of the study was to study the effects of a flexible shift system (based on self-determined work hours) with respect to sleep/wake complaints and subjective health. The comparison group was a rapidly rotating shift system, with frequently occurring quick returns. A secondary aim was to examine the relation between work hour characteristics indicating compressed or difficult rosters (e.g. number of workdays in a row, frequency of quick returns and long work shifts) and subjective sleep and sleepiness, within the flexible shift system group. The sample of the analysis included 533 randomly selected police officers, of which 26% were females. The participants answered a questionnaire. The results showed that the flexible shift system group did not differ with respect to sleep/wake complaints and subjective health. However, the flexible shift group obtained more sleep in connection with the shifts, probably because of longer rest time between shifts. Thus, they worked less quick returns and long work shifts. The association between work hour characteristics and sleep/wake complaints was weak in the flexible shift group. Instead, sleep/wake problems were mainly associated with the attitude to work hours.

Research needs in identifying preventive measures dealing with working time arrangements and associated sleep problems are reviewed. These needs are based on the recognition of a range of risk factors for health involving disturbed circadian rhythms leading to various levels of sleep deficits. The review takes account of recent joint change approaches that address both working time arrangements and various relevant intervening factors. As examples of such approaches, voluntary industry-based guidelines for improving shift work are examined. Also reviewed is evidence indicating the effects of improved working time arrangements and sleep hygiene on the tolerance of workers working irregular shifts. Trends in action-oriented risk assessment are further discussed as the effects on health and sleep of these workers may be modified by complex aspects related to working situations, family and social conditions, personal characteristics and social support. Generally relevant are not only the relationships between sleep-affecting factors and health, but also advances in taking the various support measures. The effective use of participatory steps is found important in dealing with working time arrangements and associated health and sleep problems together. It is thus considered important to study (a) the efficacy of joint change approaches addressing complex sleep and health factors, (b) effective procedures for action-oriented health risk assessment in various work life situations, and (c) the relevance of innovative participatory steps to improving health and tolerance of workers. Future research topics mentioned by the participants of the international symposium on night and shift work held in Santos in 2003 are presented, and international efforts to promote research into these aspects in field conditions are discussed. Interactive research involving local people appears crucial.

This paper reviews briefly our research findings on sleep and health for shift workers at a bakery and a dish factory and aims to give some information on health protection with improved sleep. Our medical examinations revealed that rises in blood pressure (BP) were frequently observed in male bakery workers on the fixed night shift. They took a two-hour nap from 1:00 to 3:00 during the night shifts according to our advice. As a result, their diastolic BP significantly decreased in subsequent years. Women working shifts before 3:00 at a dish factory seemed to show more sleep disturbance, higher daytime sleepiness, and more fatigue than those working shits from 3:00. Total sleep hours taken during the daytime was similar between two groups. Among the dish, factory workers who switched to midnight or night shifts, 70% reported slow recovery from fatigue and 30% felt deteriorated health. These women also reported increased efforts to obtain a deep sleep, probably making up for shortened sleep. Occupational physicians can act to improve shift work conditions through monitoring the health of workers, applying naps, and designing possible schedules to secure deep, sufficient sleep.

Increasing emphasis is currently being given to the importance of bringing knowledge gained from science into places where people live and work, in order to increase the impact science has on the general public's quality of life. Scientific findings about the positive impact of napping on mood and performance are an example of research generated knowledge that needs to be brought to the workplace. A major goal of the Napping Company (www.napping.com) is to bring the science of napping to the workers and the workplace so that employees and employers can act on this knowledge and change worker napping behavior and employer napping policies. The present paper overviews the challenges inherent in making scientific knowledge useful to how we live our lives. The Napping Company is guided by five principles of knowledge transfer in the company's attempts to disseminate and increase utilization of napping research. Examples are given to illustrate how the Napping Company has used these principles to bridge the gap between napping science and nap behavior and policies in the workplace.

Circadian Technologies, Inc. (CIRCADIAN) is an international consulting firm that for over 20 yr has helped employees better cope with shiftwork, while ensuring their employers reduce costs and maximize profits. This paper describes two of the methods employed to reduce accidents, absenteeism, and turnover, while improving morale and productivity in extended hour operations (shiftwork). Shiftworkers rarely receive on-the-job training to help them cope better with the rigors of working nights, evenings, and early mornings. A pre- and post-training study by CIRCADIAN demonstrated improvements in health and fatigue indices, and an increase in daytime sleep length. Companies who provide shiftwork lifestyle training also have lower rates of absenteeism and turnover compared to companies that do not provide training. The second intervention described in this paper is a novel method of shift scheduling. There are thousands of potential schedules, so how does a company choose the best schedule for their facility? The answer lies in allowing employees to be involved in the process of selection. This results in a workforce that experiences less fatigue, turnover and absenteeism, and higher morale.

Nighttime napping is an effective measure to prevent adverse effects due to night shift work. A characteristic of nighttime nap is that it can result in considerably deeper sleep. Several studies have shown that taking nighttime naps suppressed increasing sleepiness, decreasing alertness during the period following awaking from a nap, and prevented disturbance of circadian rhythm ("anchor sleep"). The length of daytime sleep after night shift, when combined with a nighttime nap, is shorter than that without nap. This finding might be interpreted as a beneficial effect rather than a negative feature because workers can then spend time engaged in other activities rather than sleeping. Nevertheless, the introduction of nighttime sleep break in the workplace has not been widely accepted. To promote nighttime napping strategy in the workplace, consensus building while acting on conflicting interest is essential. Recently, participatory method for improvement of working condition has expanded worldwide. A characteristic of the activity is using action checklist and group work, and heightening motivation to improvement working condition between worker and manager. Through the activities, nighttime napping strategy would be spread more in the workplaces and play a role as one of the effective tools for improving working conditions, work performance and safety in the future.

We know there are persons exposed demanding work schedules and sleep loss in almost every occupation or industry, but we still need better population-based information on how many sleepy or inattentive workers there are, where they are, and to what extent they are a risk to themselves or others. The absence of such information, however, does not prevent us from continuing to conduct worksite interventions and demonstrations that will produce good, evidence-based guidelines to help workers and workplace administrators make informed choices about sleep and provide optimal conditions for sleep. In addition, systematic study and publication of how managers and policy-makers accept our research to make worksite changes, and what factors beside our research influence their decisions, would contribute techniques to the greater public health community aiming to translate research results into good practice.