Prevention and treatment of sleep deprivation among emergency physicians

Emergency physicians commonly experience sleep deprivation because of the need to work shifts during evening and late night hours. The negative effects of this problem are compounded by job stress and traditional methods of scheduling work shifts. Sleep deprivation may be reduced by schedules designed to lessen interference with normal sleep patterns and circadian rhythms. Pharmacological treatments for sleep deprivation exist in the form of alertness-enhancing agents, caffeine and modafinil. Sleep-promoting agents may also help treat the problem by helping physicians to sleep during daytime hours. Minimizing sleep deprivation may help prevent job burnout and prolong the length of an emergency physician's career.

[Health examinations in connection with night work]

Some 10% of the labour force work during night hours. According to an EU directive night workers should be offered preventive health examinations. It is well known that night work is related to sleep disorders but the epidemiologic evidence linking night work with increased occurrence of peptic ulcers, breast cancer, cardiovascular disease and spontaneous abortions is still limited and provides no strong rationale for preventive health examinations. This article argues that individual health examinations should be integrated into primary preventive activities at the workplace.

Effect of shift work on body mass index and metabolic parameters

OBJECTIVES

The aim of this cohort study was to investigate the effects of shift work on changes in parameters related to metabolic disturbances.

METHODS

The study population included 1529 male blue-collar workers, aged 19-49 years at baseline, working in a sash and zipper factory in Japan. The participants were divided into four groups according to the work schedule at baseline, the end point being workers doing fixed daytime work in both years (day-day), workers who changed from shift work to fixed daytime work (shift-day), workers who changed from fixed daytime work to shift work (day-shift), and workers doing shift work in both years (shift-shift). The changes in body mass index (BMI), blood pressure, serum cholesterol, and glycosylated hemoglobin A1c over a period of 10 years were compared among the groups by work schedule.

RESULTS

The age-adjusted mean increase in BMI was 1.03 kg/m(2) for the day-shift workers, and it was significantly larger than that of the day-day workers and shift-day workers. The shift-shift workers showed a significantly larger increase in BMI than the day-day workers. These tendencies remained after adjustment for age and all other confounding factors, such as BMI, smoking, drinking, and leisure-time physical activity at baseline. The increase in total cholesterol tended to be higher among the shift-shift workers and the day-shift workers, but there were no significant differences. Blood pressure and hemoglobin A1c did not differ among the four groups.

CONCLUSIONS

Shift work is considered to be a risk factor for excess weight. However, no significant difference in the biomarkers was found between daytime workers and shift workers.

Chronobiology of sleep in humans

Periodic circadian (24-h) cycles play an important role in daily hormonal and behavioural rhythms. Usually our sleep/wake cycle, temperature and melatonin rhythms are internally synchronized with a stable phase relationship. When there is a desynchrony between the sleep/wake cycle and circadian rhythm, sleep disorders such as advanced and delayed sleep phase syndrome can arise as well as transient chronobiologic disturbances, for example from jet lag and shift work. Appropriately timed bright light is effective in re-timing the circadian rhythm and sleep pattern to a more desired time, ameliorating these disturbances. Other less potent retiming effects may also be obtained from the judicious use of melatonin and exercise.

Overtime, job stressors, sleep/rest, and fatigue of Japanese workers in a company

To ascertain the usefulness of a 21-item checklist that assesses accumulated fatigue due to overwork, we examined (1) the associations between overtime work, job stressors, or the quantity of sleep/rest and subjective symptoms of fatigue, and (2) whether sleeping hours and monthly days off are associated with the accumulated fatigue parameter using the checklist. Questionnaire surveys were administered twice to Japanese workers at a plant of a manufacturing company. Among the 390 registered workers, 383 workers (284 males and 99 females) in the first survey and 350 workers (260 males and 90 females) in the second survey responded. The subjective symptoms score significantly increased according to the order of grade of overtime work, other job stressors, and sleep/rest subscales in both sexes by ANOVA. The subjective symptoms grade was significantly associated with the other job stressors grade and sleep/rest grade, but not with overtime work. The accumulated fatigue parameter was negatively correlated with daily sleeping hours (significant Spearman's correlation coefficient (r(s)) =-0.318 and -0.340 in the 1st and 2nd surveys) and with monthly days off (r(s)=-0.250 and -0.151) among all of the subjects. It may be possible to assess overwork by the accumulated fatigue parameter.

Subjective poor sleep and white blood cell count in male Japanese workers

Sleep deprivation has been shown to be associated with an increase in inflammatory makers such as interleukin-6 and C-reactive protein. The purpose of the present study was to investigate the relation between subjective poor sleep and white blood cell (WBC) count, an inflammatory marker. The subjects were 208 male Japanese workers in a synthetic fiber-manufacturing plant, who responded to a cross-sectional survey of a questionnaire on basic attributes, life style, and sleep. All male workers in the plant took an annual health checkup. WBC count was also examined in the checkup. The WBC count was greater in shift workers than in daytime workers. Shift workers complained of poor sleep more frequently, though their sleeping hours were longer. Multiple regression analysis showed that poor sleep as well as smoking habit, BMI and age were independent factors for an increase in WBC count, while sleeping hours and work pattern (shift work) were not significant factors. The present finding that poor sleep was associated with higher WBC count in male workers might suggest the importance of quality of sleep, particularly among shift workers.

Risk of prematurity, low birthweight and pre-eclampsia in relation to working hours and physical activities: a systematic review

BACKGROUND

Occupational activities are suspected of having an adverse impact on outcomes of pregnancy.

AIM

To assess the evidence relating three major adverse outcomes (preterm delivery, low birthweight (LBW) and pre-eclampsia/gestational hypertension) to five common occupational exposures (prolonged working hours, shift work, lifting, standing and heavy physical workload).

METHODS

A systematic search of Medline and Embase (1966-December 2005) using combinations of keywords and medical subject heading terms was conducted. For each relevant paper, standard details were abstracted that were then used to summarise the design features of studies, to rate their methodological quality (completeness of reporting and potential for important bias or confounding) and to provide estimates of effect. For studies with similar definitions of exposure and outcome, pooled estimates of relative risk (RR) in meta-analysis were calculated.

RESULTS

53 reports were identified-35 on preterm delivery, 34 on birth weight and 9 on pre-eclampsia or gestational hypertension. These included 21 cohort investigations. For pre-term delivery, extensive evidence relating to each of the exposures of interest was found. Findings were generally consistent and tended to rule out a more than moderate effect size (RR >1.4). The larger and most complete studies were less positive, and pooled estimates of risk pointed to only modest or null effects. For small-for-gestational age, the position was similar, but the evidence base was more limited. For pre-eclampsia and gestational hypertension, it was too small to allow firm conclusions.

CONCLUSIONS

The balance of evidence is not sufficiently compelling to justify mandatory restrictions on any of the activities considered in this review. However, given some uncertainties in the evidence base and the apparent absence of important beneficial effects, it may be prudent to advise against long working hours, prolonged standing and heavy physical work, particularly late in pregnancy. Our review identifies several priorities for future investigation.

Influence of work duration or physical symptoms on mental health among Japanese visual display terminal users

The present study examined the relationship of work duration or physical symptoms to the mental health of visual display terminal (VDT) workers in Japan. The mental health status of 2,327 VDT users at an administrative office was investigated using the 12-item General Health Questionnaire (GHQ-12). Subjects were asked about their age, sex, hours of daily VDT use, rest and breaks during VDT work, eyestrain, and musculoskeletal pain. Logistic regression analysis was used to evaluate the associations with mental health status (GHQ-12 scores). The mean age of subjects was 39.5 yr (SD=10.3). Among all subjects, 36.7% could rest during VDT work and 66.9% received breaks during VDT work. The proportion of subjects who reported eyestrain and musculoskeletal pain were 19.6% and 25.7%, respectively. Eighteen percent of subjects were classified into a GHQ-12 high score group. Logistic regression analysis showed that age less than 40 yr, not receiving breaks during VDT work, and the presence of eyestrain and musculoskeletal pain were significantly associated with poor mental health status (high GHQ-12 scores). Using a VDT for more than 5 h/d and being female were also marginally associated with high GHQ scores (p<0.1). In conclusion, the management of physical health as well as work duration is important for good mental health status among VDT users.

Electroencephalography artifacts in workplace alertness monitoring

OBJECTIVE

This study assessed the effect of removing artifacts from workplace electroencephalography (EEG) recordings on power spectra and the consequent interpretation of changes in alertness.

METHODS

EEG was recorded for 27 air traffic controllers on the night shifts of four roster cycles. On two of the four night shifts, each controller was given a 40-minute opportunity to nap, while on the other two they remained awake (105 shifts in total). Recordings for the last hour of each night shift were screened for artifacts by an experienced viewer (who viewed the EEG in isolation from other electrophysiological recordings). The effects of the nap opportunity on the EEG power spectra were then analyzed in a mixed model analysis of variance in the presence and absence of artifact-contaminated data.

RESULTS

Overall, 89.3% of the EEG recordings contained artifacts. Removal of these data markedly altered the interpretation of how the nap opportunities affected the EEG power spectra. The spectral parameters of the artifact appeared to be different when the participants were given the opportunity to nap.

CONCLUSIONS

Removal of artifacts can dramatically affect the interpretation of workplace EEG recordings. This potential source of error is often unreported.

Do long workhours impact health, safety, and productivity at a heavy manufacturer?

OBJECTIVES

To test the health, safety, and productivity effects of long workhours.

METHODS

Secondary analyses of a longitudinal employee panel (n = 2746). Average hours worked during spring 2001 were assessed relative to health, safety, and productivity outcomes spanning summer 2001 through spring 2002.

RESULTS

Employees working overtime were no more likely to incur adverse physical or mental health, presenteeism, or disability outcomes. Those working 60+ hours were more likely to report new injuries and diagnoses, but these effects were overwhelmed by prior health, demographics, and compensation type.

CONCLUSIONS

Much previous work has suggested that long workhours generate a wide range of adverse outcomes across the employee continuum. This study found no evidence for pervasive workhour effects. Rather, long workhours--especially weekly schedules at the 60 hour or above mark--can lead to problems in certain areas of health and safety. More research is needed that tests group differences across segmented characteristics (eg, poor versus good health) but keeps workhour impact in perspective.

Effects of rotating shift work on biomarkers of metabolic syndrome and inflammation

OBJECTIVE

The major function of the circadian system is the internal cycling of physiological and metabolic events. The present study sought to explore the effect of rotating shift work schedule on leucocyte count and its relationship with risk factors of metabolic syndrome (MS).

DESIGN AND PARTICIPANTS

From a population-based design, 1351 men of self-reported European ancestry were included in a cross-sectional study: 877 day workers were compared with 474 rotating shift workers. Medical history, health examination including anthropometric and arterial blood pressure measurements, a questionnaire on health-related behaviours and biochemical determinations was given to all participants.

RESULTS

In comparison with day workers, rotating shift workers had elevated (mean +/- SE) body mass index (27.1 +/- 0.3 vs. 26.3 +/- 0.2, P < 0.0154), waist-hip ratio (0.95 +/- 0.01 vs. 0.93 +/- 0.01, P < 0.00024), diastolic arterial blood pressure (78 +/- 1 vs. 76 +/- 1, P < 0.033), fasting insulin (65.5 +/- 2.9 vs. 55.9 +/- 1.9 pmol L(-1), P < 0.017), Homeostasis Model Assessment index (2.12 +/- 0.11 vs. 1.77 +/- 0.07, P < 0.0027), triglycerides (1.71 +/- 0.1 vs. 1.5 +/- 0.1 mmol L(-1), P < 0.002), uric acid (292.7 +/- 2.8 vs. 282 +/- 3.4 micromol L(-1), P < 0.01) and leucocyte count (7030 +/- 84 vs. 6730 +/- 58, P < 0.0094). In multiple regression analysis, leucocyte count was correlated with rotating shift work independently of age, smoking, education and components of MS.

CONCLUSION

The odds ratio for MS in rotating shift workers compared with day workers was 1.51 (95% CI 1.01-2.25), independently of age and physical activity. Increased leucocyte count, a biological marker of systemic inflammation, was associated with rotating shift work.

Estimation of the number of working hours critical for the development of mental and physical fatigue symptoms in Japanese male workers - application of benchmark dose method

BACKGROUND

To clarify the influence of working hours on subjective fatigue symptoms and obtain the critical dose (number of hours) to determine the number of permissible working hours, we calculated the benchmark dose (BMD) and the 95% lower confidence limit on BMD (BMDL) of working hours for subjective mental and fatigue symptoms using multivariate logistic regression.

METHODS

Self-administered questionnaires were distributed to all 843 male daytime workers aged < or = 60 years in a single chemical factory, and 715 provided complete replies. The odds ratios of daily working hours were determined using positive findings of the Self-rating Depression Scale and 8 subscales of the Cumulative Fatigue Symptom Index as dependent variables, and other potential covariates as independent variables. Using significant parameters for the working hours and those for other covariates, the BMD and BMDL (BMD/BMDL) values were calculated for corresponding dependent variables. The benchmark response (BMR) was set at 5% or 10%.

RESULTS

The BMDL with a BMR of 5% was shown to be 9.6-11.6 hr per day, which corresponds to 48-58 working hours per week and 36-78 overtime hours per month.

CONCLUSIONS

These results suggest that special attention should be paid to the workers whose working hours exceed these BMD/BMDL values.

Simulator driving performance, subjective sleepiness and salivary cortisol in a fast-forward versus a slow-backward rotating shift system

OBJECTIVES

The objectives of this study were to examine simulator driving and subjective sleepiness after morning, afternoon, and night shifts and to compare these differences, as well as objective stress, between a fast-forward and a slow-backward rotating shift system.

METHODS

The participants were male volunteers working in a chemical plant, 18 in a slow-backward rotating system and 18 in a fast-forward rotating system. All of the participants performed a driving simulator test and subjectively estimated sleepiness after a night, afternoon, and morning shift. Salivary cortisol samples, as indicators of the objective stress level, at the beginning of the workweek-after the second morning shift-were compared between the two rotating shift systems.

RESULTS

Lane drifting was higher after a night shift than after an afternoon shift. No effect of rotation system on driving performance could be shown. The subjective sleepiness scores were significantly higher in the slow-backward rotating group than in the fast-forward rotating group. A significant effect of shift type was also observed, with lower levels of sleepiness after the afternoon shift than after the morning and night shifts. Salivary cortisol samples taken at the start of the workweek did not significantly differ between the fast-forward and the slow-backward rotation shift systems.

CONCLUSIONS

This study indicated that shift type is more important than shift schedule-direction and speed of rotation-in determining driving performance. Performance seemed to be threatened mostly by a night shift and the least by an afternoon shift. In contrast, subjective sleepiness also differed between rotation groups and indicated an advantage of the fast-forward rotation system. The exploratory salivary cortisol measurements suggested that the shift systems studied do not differ in the level of stress they induce, that is to say at the beginning of the workweek.

Impact of Shift Work on the Health and Safety of Nurses and Patients

Shift work generally is defined as work hours that are scheduled outside of daylight. Shift work disrupts the synchronous relationship between the body's internal clock and the environment. The disruption often results in problems such as sleep disturbances, increased accidents and injuries, and social isolation. Physiologic effects include changes in rhythms of core temperature, various hormonal levels, immune functioning, and activity-rest cycles. Adaptation to shift work is promoted by reentrainment of the internally regulated functions and adjustment of activity-rest and social patterns. Nurses working various shifts can improve shift-work tolerance when they understand and adopt counter measures to reduce the feelings of jet lag. By learning how to adjust internal rhythms to the same phase as working time, nurses can improve daytime sleep and family functioning and reduce sleepiness and work-related errors. Modifying external factors such as the direction of the rotation pattern, the number of consecutive night shifts worked, and food and beverage intake patterns can help to reduce the negative health effects of shift work. Nurses can adopt counter measures such as power napping, eliminating overtime on 12-hour shifts, and completing challenging tasks before 4 am to reduce patient care errors.

Sleep debt and outside employment patterns in helicopter air medical staff working 24-hour shifts

INTRODUCTION

Twenty-four hour availability creates physiological and psychological challenges for air medical teams. The 24-hour shift (24H) is a common staffing pattern in the air medical community. We report sleep dept and pre-duty activity patterns for 24H medical staff members at helicopter air medical transport programs.

METHODS

An anonymous survey collecting self-reported sleep quantities for off-duty, immediate pre-duty, and on-duty periods, along with self-reported outside employment patterns, was distributed to medical team members at cluster sample of 10 rotor wing air medical programs selected by stratified random sample to ensure geographic and operational diversity. Both matched-sample comparisons of sleep quantities in different phases of the duty-cycle and independent-sample comparisons between staff with and without outside employment had 80% power to detect a difference in means of 60 minutes at a 0.05 two-sided significance level using the appropriate t-test. Descriptive statistics are also reported; means are reported with the standard deviation.

RESULTS

A total of 138 surveys were returned (69.0%) and the 133 (66.5%) that were fully completed were utilized for analysis. 24H crewmembers average nearly the same amount of sleep in 24 hour periods on both duty and non-duty days (6.9 +/- 1.3 v. 6.4 +/- 1.8 hours, p = NS, range 3 - 10 for duty days and 4 - 10 for non-duty days). On duty, they average 1.1 +/- 1.3 hours of sleep in the first half of their shifts (range 0 to 5) and 5.3 +/- 1.4 hours in the overnight portion (range 2 - 9). The lowest amount of on-duty sleep reported in the past 30 days ranged from 0 to 6 hours, averaging 1.9 +/- 1.7 hours. The minimum pre-duty sleep reported by 24H crewmembers prior to any shift in the past month averaged 4.6 +/- 1.6 hours (range 0-8), with 3.8% having reported in the past month with no sleep before their 24-hour shift. Outside employment (OE) in addition to the flight position was common for 24H crewmembers (81.1% of respondents). Pre-duty sleep did not differ significantly between 24H crewmembers with and without OE, but 16.3% of surveyed 24H crewmembers with OE had reported for flight duty within eight hours of leaving OE within the past 30 days.

CONCLUSION

In the programs surveyed, 24H crewmembers completed an average duty cycle with little sleep debt and were unlikely to be sleepless prior to reporting for a shift. OE is common for 24H medical staff and some personnel report for flight duty within eight hours of leaving an OE position. As the industry considers the impact of fatigue on operational safety, shift length, on-duty rest, and outside employment will be important considerations.

Extended work periods

A literature review of 105 studies on the effects of extended daily working hours was conducted. Potential negative effects of extended working hours are discussed: More accidents on the job; more accidents off the job; reduced duration and quality of sleep due to moonlighting; sleepiness; reduced alertness; fatigue; adverse effects on performance; prolonged toxic exposure; adverse effects on health; increased absenteeism; problems communicating with managers; and problems while driving home. Potential positive effects of extended working hours are discussed: Less travel time and costs; more time for the family, social life, and domestic duties; increased satisfaction with working hours; fewer handovers; and less overtime. No firm conclusions can be drawn because of the partly contradictory results and the methodological problems of many studies. However, caution is advised when considering the introduction of extended work shifts, particularly where public safety is at stake. A checklist is provided (concerning work load, breaks, staffing level, systematic assessments of health and safety factors) to support decisions for or against the use of extended work shifts.

Submarine watch schedules: underway evaluation of rotating (contemporary) and compressed (alternative) schedules

INTRODUCTION

With a desire to increase health, cognitive performance effectiveness, and quality of life for submarine watch-standers underway, we performed an evaluation comparing an alternative, compressed-work (ALT) schedule, designed to enhance circadian rhythm entrainment and sleep hygiene, to the contemporary submarine (SUB) forward rotating schedule, aboard the ballistic-missile submarine, USS Henry M. Jackson (SSBN-730 Gold).

METHODS

We assessed a compressed close-6 watch-schedule ("ALT") relative to the existing backward rotating 6-hr on, 12-hr off 18-hr watch schedule ("SUB") employed underway aboard submarines. We monitored 40 subjects' sleep, and temperature and salivary cortisol from 10 of the 40 for approximately two weeks on each respective schedule underway.

RESULTS

The cortisol cosinor mesors (midline estimating statistic of rhythm), and amplitudes did not differ significantly between conditions. The temperature cosinor mesors, and the cosinor amplitude were not significantly different, while the cosine curve fit accounted for significantly more variance in the ALT condition than in the SUB condition. The SUB schedule garnered significantly more sleep (7.1 +/- 0.2 hours) than that of the ALTMID schedule (6.3 +/- 0.3 hours). Surveys revealed that 52% of respondents preferred the SUB schedule, 15% preferred the ALT, and 33% were either indifferent or submitted uninterpretable surveys.

CONCLUSIONS

The ALT schedule was not superior to the existing SUB schedule by physiological or subjective measures and was incompatible to accommodating operational constraints.

Subjective Fatigue and Stress Hormone Levels in Urine according to Duration of Shiftwork

To determine the associations between urinary catecholamines and cortisol and subjective complaints of fatigue in shiftworkers, we conducted a field survey of 113 male shiftworkers at a manufacturing company in South Korea from late October to late November in 1999. The shiftwork system in the company was the backward rapidly rotating 4-crew 3-shift, with the morning shift starting at 7:30 AM. Using a self-report questionnaire, we assayed demographic characteristics, past medical history and working hours, as well as subjective complaints of fatigue in 3 categories of questionnaire. We found that, among workers with less than 5 yr of shiftwork experience, the concentrations of norepinephrine, epinephrine (Epi), and dopamine during the afternoon shift were positively correlated with Set II (difficulties in concentration) and Set III (projection of disintegration) of subjective fatigue symptoms. In addition, Epi concentrations were positively correlated with Set I (drowsiness and dullness), II, and III of subjective fatigue symptoms during the night shift. However, among workers with 5 or more years of shiftwork experience, there was no significant positive correlation between urinary catecholamine and subjective fatigue symptoms. In the long term shiftwork experience group, only the complaints scores of Set II fatigue symptoms (difficulties in concentration) during the morning shift were significantly higher than those of the short-term shiftwork experience group within the same shift.

Anxiety, musculoskeletal and visual disorders in video display terminal workers

AIM

The increase in the working population assigned to video display terminals (VDT) has led to ever growing attention to reports on health effects. We studied musculoskeletal and visual disorders and levels of anxiety in 2 groups of VDT operators with different tasks, in order to evaluate if they could be influenced by organizational and intrinsically working factors.

METHODS

The study included 190 VDT operators, subdivided into 2 groups (A and B) on the basis of tasks performed and average hours/ week spent at VDT (25 vs 36), and 190 controls not assigned to VDT. Ocular and musculoskeletal subjective symptoms and objective findings were assessed for all subjects, and the State-Trait Anxiety Inventory (STAI) test was administered.

RESULTS

For VDT operators of the 2 groups, the relationship between ocular and musculoskeletal symptoms and findings, working life (P=0.0001) and number of hours spent at the VDT (symptoms P=0.001 and P=0.0001; findings P=0.002 and P=0.007), was significant. Group B VDT operators showed significantly higher state anxiety (S-anxiety) levels vs those in Group A and controls (P=0.001); trait anxiety (T-anxiety) was significantly higher in Group B and controls vs Group A (P=0.001 and P=0.03).

CONCLUSIONS

Our results confirm the literature data about musculoskeletal and visual disorders and, as for anxiety, seem to denote a higher relevance of factors related to labor organization vs VDT use per se.