Objectives-To compare the relative effects on performance of sleep deprivation and alcohol. Methods-Performance eVects were studied in the same subjects over a period of 28 hours of sleep deprivation and after measured doses of alcohol up to about 0.1% blood alcohol concentration (BAC). There were 39 subjects, 30 employees from the transport industry and nine from the army. Results-After 17-19 hours without sleep, corresponding to 2230 and 0100, performance on some tests was equivalent or worse than that at a BAC of 0.05%. Response speeds were up to 50% slower for some tests and accuracy measures were significantly poorer than at this level of alcohol. After longer periods without sleep, performance reached levels equivalent to the maximum alcohol dose given to subjects (BAC of 0.1%). Conclusions-These findings reinforce the evidence that the fatigue of sleep deprivation is an important factor likely to compromise performance of speed and accuracy of the kind needed for safety on the road and in other industrial settings. (Occup Environ Med 2000;57:649-655) Keywords: sleep deprivation; performance; alcohol The implications of fatigue for safe performance are well recognised particularly in road safety, but in other settings as well. Fatigue is most likely to occur when rest is reduced such as when working long or irregular hours, doing shift and night work, or due to family responsibilities or lifestyle choices. EVects of fatigue are thought to play a part in between 16% and 60% of road accidents 1 2 and in the United States were estimated to cost in the vicinity of $50 billion. Recently authors have argued that until now society has simply accepted the hazards of fatigue despite evidence of increased risk to health and safety.4 5 This has led to calls for better information on the extent and consequences of the eVects of fatigue on performance.6 The problem, in practice, is at what level of fatigue does performance become a problem? In setting any safety standard for the fatigue caused by sleep deprivation, the sort of information needed is a comparison of performance after a known number of hours spent awake with that caused by some other agent that decreases performance.Alcohol eVects serve as a good model for an acceptable standard for safe performance. Alcohol eVects have been measured and standardised by setting limits on alcohol consumption based on their predicted eVects on driving performance.7 Many countries have set limits for alcohol levels while driving which are based on laboratory, simulator, and on road measures of speed and accuracy of performance.8 These standards provide a benchmark for performance deficits caused by injury, illness, or in this case, the fatigue of sleep deprivation. By comparing the change in performance due to alcohol consumption at concentrations widely agreed to be hazardous (0.05% blood alcohol concentration (BAC)) 8 with the same behaviour after sleep deprivation, it should be possible to assess the amount of sleep deprivation at which equivalent deficits occu...

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SUMMAR Y The purpose of this workplace evaluation was to assess the effects on performance, alertness and subsequent sleep of strategic napping on 12-h overnight shifts. In a counterbalanced crossover design, 24 male aircraft maintenance engineers working in a forward rotating 12-h shift pattern volunteered to take part in the study for two work weeks. During the experimental week, each subject was given the opportunity to take a 20-min nap at work between 01:00 and 03:00 h on each of their two overnight shifts. On the control week no naps were taken on the night shifts. A computerized neurobehavioural test battery was employed to assess performance and subjective levels of fatigue at the beginning and end of each night shift, and pre-and postnap. Subjects were also asked to rate how near they had come to falling asleep while driving to and from work. The results revealed that taking a single 20-min nap during the first night shift significantly improved speed of response on a vigilance task measured at the end of the shift compared with the control condition. On the second night shift there was no effect of the nap on performance. Taking a short nap during either night shift had no significant effect on subjective ratings of fatigue, the level of sleepiness reported while driving to and from work, or subsequent sleep duration and sleep quality. Overall the results suggest some promise for a short duration nap taken in the workplace to counteract performance deficits associated with the first night shift.k e y w o r d s napping, night shift, fatigue, performance, sleep

Objective-To examine risk factors for onset of low back pain (LBP) in healthcare workers. Methods-Nursing students, during their 3 year training period, and 1 year after training were studied in a prospective cohort study, with repeated self reported measurements of determinants of LBP at 6 monthly intervals for 3 years during training, and after a 12 month interval there was an additional final follow up. Results-During training, increased risk of new episodes of LBP was associated with having had LBP at baseline, with part time work, and with a high score on the general health questionnaire (GHQ). A high GHQ score preceded the onset of LBP, in such a way that a high score at the immediately previous follow up increased risk of LBP at the next follow up. 12 Months after training, a history of recurring LBP during training increased the risk of a new episode as did having obtained work as a nurse. A high GHQ score at this follow up was also associated with a concurrently increased risk. Preexisting GHQ score, either at the end of training or at baseline, had no eVect on risk of LBP 12 months after training. Conclusions-Other than a history of LBP, pre-existing psychological distress was the only factor found to have a pre-existing influence on new episodes of LBP. Increased levels of psychological distress (as measured by the GHQ) preceded the occurrence of new episodes of pain by only short intervening periods, implying a role for acute distress in the onset of the disorder. This finding suggests that management of the onset of occupational LBP may be improved by management of psychological distress. (Occup Environ Med 2000;57:116-120) Keywords: low back pain; nurses; psychological factors At some time in their lives, most people will experience low back pain (LBP).1 2 It is the most common and the most expensive source of compensated work related injury in modern industrialised countries.3 4 Moreover, both the rate and the degree of disability accruing from LBP are increasing worldwide. Physical load on the back has commonly been implicated as a risk factor for LBP, and in particular, for work related LBP. Certain occupations and certain work tasks seem to have a higher risk of LBP.7-10 However, the evidence for the relation between physical load and musculoskeletal disease has often been weak or contradictory, and it is generally agreed that work related physical load can only partially explain the high prevalence of the problem. 11By contrast, association of non-physical factors with LBP has been one of the more robust findings in the scientific literature. Psychological factors have been consistently found to be associated with LBP, with disability arising from LBP, and with treatment outcome. 12-16Poor psychosocial work environment and work dissatisfaction have also been found to be associated with LBP and the development of chronicity 12 17 18 although contradictory findings have been reported. 19 20 Despite the many publications examining LBP, several key issues concerning occurrence and pr...

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