An occupational health physician's report on the improvement in the sleeping conditions of night shift workers

Work schedule and self-reported hypertension - the potential beneficial role of on-shift naps for night workers

Data on the association between shift work and hypertension are controversial. Sleep restriction is hypothesized to be involved in this relationship. Since on-shift nap can partly compensate for sleep deprivation among night workers, this investigation is aimed at (i) comparing the prevalence of hypertension among workers considering both current and former night work, (ii) testing the association between on-shift naps and hypertension among night workers, and (iii) analyzing the influence of sleep complaints in the association between on-shift nap and hypertension. Nap was defined as a sleep episode with duration shorter than the average nighttime sleep. A cross-sectional study was performed at the 18 largest public hospitals in Rio de Janeiro, Brazil, in 2010-2011 (N = 2588 female registered nurses). Nurses were informally allowed to nap for up to three consecutive hours during working nights. Workers completed a multidimensional questionnaire including self-reported information on physician diagnosis of hypertension, napping, and sleep complaints (insomnia, diurnal sleepiness, and non-satisfactory sleep). Epidemiological and statistical treatment of data included binomial logistic regression and interaction tests. Higher chances of hypertension were observed for both current and former night workers compared with workers with no previous experience in night work, i.e. exclusive day workers (OR = 1.68; CI95% 1.22-2.33 and OR = 1.40; CI95% 1.01-1.96, respectively) after adjustment for age, race/ethnicity, physical activity, smoking, alcohol consumption, insomnia, weekly work hours, and BMI. Compared with exclusive day workers, both non-nappers and nappers were at a higher likelihood of reporting hypertension (OR = 1.93 CI95% 1.35-2.79 and OR = 1.41 CI95% 1.08-2.20, respectively). An interaction was observed between napping behavior and insomnia (p = 0.037). In the whole sample of night workers, the lower OR for nappers was confirmed when they were directly compared with non-nappers (OR = 0.76 CI95% 0.59-0.98). Analysis of night workers stratified by insomnia showed a significant reduction in OR for nappers (compared to non-nappers) only among insomniacs (OR = 0.58). Napping during night work may be a protective factor for hypertension, particularly among insomniacs. Factors related to melatonin secretion, blood pressure control, and blood pressure dipping patterns are likely to be involved in the relationship between on-shift napping and blood pressure.

The cost of poor sleep: workplace productivity loss and associated costs

OBJECTIVE

To assess the impact of sleep disturbances on work performance/productivity.

METHODS

Employees (N = 4188) at four US corporations were surveyed about sleep patterns and completed the Work Limitations Questionnaire. Respondents were classified into four categories: insomnia, insufficient sleep syndrome, at-risk, and good sleep. Employer costs related to productivity changes were estimated through the Work Limitations Questionnaire. Performance/productivity, safety, and treatment measures were compared using a one-way analysis of variance model.

RESULTS

Compared with at-risk and good-sleep groups, insomnia and insufficient sleep syndrome groups had significantly worse productivity, performance, and safety outcomes. The insomnia group had the highest rate of sleep medication use. The other groups were more likely to use nonmedication treatments. Fatigue-related productivity losses were estimated to cost $1967/employee annually.

CONCLUSIONS

Sleep disturbances contribute to decreased employee productivity at a high cost to employers.

Recovery of cognitive performance and fatigue after one night of sleep deprivation

OBJECTIVES

The aim of this study was to investigate how subjective sleepiness, mood states, simple and high-order cognitive performance change after one night of sleep deprivation (SD) and recover to after 7 h normal recovery sleep opportunity during three recovery days.

METHODS

Ten healthy subjects participated in this study. We measured their subjective sleepiness, mood states and their performances of 2 simple tasks and 4 high-order cognitive tasks twice a day for 5 days, on the baseline day, post-vigil day and 3 recovery days after SD. This study was conducted considering each participant's motivation for task, learning effect and diurnal variation of performance.

RESULTS

The performances of simple tasks such as addition or short-term memory were not reduced after SD and were the poorest on the baseline day, and improved gradually; however the high-order cognitive performances were at their lowest on the post-vigil day and needed 2 recovery sleep opportunities to return to the baseline level. Fatigue and confusion in mood states and subjective sleepiness were also at their lowest after SD. Subjective sleepiness nearly recovered to the baseline level on the 1st recovery day, but fatigue and confusion reached the baseline levels on the 2nd recovery day.

CONCLUSION

These results suggest that cognitive deterioration and the recovery process may differ between simple task performance and high-order cognitive task performance, which needed 2 ordinary sleep opportunities to recover to the baseline level, and the change of subjective mood states were also different for each mood.

Optimal shift duration and sequence: recommended approach for short-term emergency response activations for public health and emergency management

Since September 11, 2001, and the consequent restructuring of the US preparedness and response activities, public health workers are increasingly called on to activate a temporary round-the-clock staffing schedule. These workers may have to make key decisions that could significantly impact the health and safety of the public. The unique physiological demands of rotational shift work and night shift work have the potential to negatively impact decisionmaking ability. A responsible, evidence-based approach to scheduling applies the principles of circadian physiology, as well as unique individual physiologies and preferences. Optimal scheduling would use a clockwise (morning-afternoon-night) rotational schedule: limiting night shifts to blocks of 3, limiting shift duration to 8 hours, and allowing 3 days of recuperation after night shifts.

Perceived sleepiness of non-shift working men in two different types of work organization

Increased sleepiness at work is increasingly being focused on as a safety and health issue. However, research on workers' sleepiness is very limited in scope and the characteristics of work organization, including the impact of job stress, have not been fully addressed. A questionnaire survey was conducted to investigate the prevalence of daytime sleepiness and its associated factors among non-shift working men at two manufacturing businesses: Company A, having a rapid rate of development and growth, with 564 workers (19-61 yr old, mean age: 32.7, response rate: 81.4%); and Company B, long established, possessing a huge production facility, with 1,654 workers (20-63 yr old, mean age: 37.1, response rate: 78.2%). The prevalence of daytime sleepiness was 11.3% in company A and 16.8% in company B. Multivariate logistic regression analysis revealed that, in company A, perceived sleepiness was associated with long sleep duration on non-working days and high cognitive demands and, in company B, with insufficient daily sleep, single, and depression. Psychosomatic exhaustion resulting from jobs requiring high adaptivity due to rapid frequency of operational change as in company A may have the potential to become an important factor in perceived sleepiness. However, in a comparatively stable work organization, as in company B, increased sleepiness may be mainly linked to factors outside work. It is suggested that not only lifestyle and sleep habits, but also the characteristics and dynamics of a work organization should be a focus of attention when planning measures to prevent sleepiness at work.