Irregular Shift Work Research Articles

The ageing shift worker: a prospective cohort study on need for recovery, disability, and retirement intentions.

This study investigates whether different shift work schedules, compared to day work, are associated with need for recovery (NFR), future disability, and retirement intentions for employees employed within different economic sectors over the course of their careers. Shift work exposure duration and the healthy worker effect are also examined. Data from the prospective Maastricht Cohort Study was used. Subsamples of industry (N=1877, all men) and healthcare (N=818, 624 women and 194 men) workers were separately investigated. GEE and Cox regression analyses were performed to investigate NFR longitudinally. Future disability was investigated using Cox regression, and retirement intentions were investigated using logistic regression analysis. Three-shift industry workers were at risk of becoming a case of elevated NFR during follow-up, compared to industry day workers. Three- and five-shift industry workers were at risk for future disability. In healthcare, irregular shift work was a risk factor for disability among older shift workers. No significant results were found regarding retirement intentions. Findings were probably an underestimation as exposure duration to shift work and the healthy worker effect affected the results. Shift work was associated with higher levels of NFR and a higher risk of disability. However, shift work is a multifaceted concept as different types of shift work schedules are differently associated with these outcomes. Different shift work types exist and shift work schedules allow for optimization, indicating that measures to prevent adverse outcomes should be tailored for different types of shift work and over the course of the work career.

Dangerously Sleepy: Overworked Americans and the Cult of Manly Wakefulness by Alan Derickson (review)

Reviewed by: Dangerously Sleepy: Overworked Americans and the Cult of Manly Wakefulness by Alan Derickson Brigitte Steger Alan Derickson. Dangerously Sleepy: Overworked Americans and the Cult of Manly Wakefulness. Philadelphia: University of Pennsylvania Press, 2014. xiii + 224 pp. $49.95 (978-0-8122-4553-0). The fraught relationship between sleep and work in modern American history is the topic of this book, which focuses on “wakefulness as a measure of masculinity” (p. x) and the impact of working conditions on health (p. xi). In the first chapter, “Sleep is for Sissies,” men of achievement such as Benjamin Franklin, Thomas Edison, Charles Lindbergh, and Donald Trump cite a reduction in their sleeping hours not only as a reason for their success, but also as a measure of their self-discipline and virtuous work ethic. Derickson argues that “these iconic figures, along with many others, fashioned a tradition of heroic manly sleeplessness that valorized wakefulness” (p. 26). The second chapter argues that restrictions on night-time labor and the protection of workers’ rights to sleep in the United States were motivated mainly by the potential impact on other people rather than damage to the health of the workers themselves. As women played a vital role in ensuring the health of the future generation by bearing and raising children, they were more likely to be protected from (or restricted to) night-time work, whereas working hours for men were reduced only for the sake of public safety or greater efficiency for the employer. The three main chapters introduce case studies of shift workers in the steel industry, Pullman sleeping car porters, and long-haul truck drivers. Derickson discusses the struggle by the labor unions and individual workers for longer sleep breaks, and the resistance they encountered from employers. Steel production in America was characterized by long, irregular shift work and cramped housing conditions, which resulted in sleep disorders, exhaustion, on-the-job injuries, and alcoholism. With a seemingly inexhaustible pool of willing immigrants, steel industrialists felt little pressure to improve working conditions, despite pressure from social scientists. It was only in 1923 that the twelve-hour working day was abolished, due partly to the insight that better working conditions could lead to improved efficiency. From the outset in 1867, Pullman hired only African Americans as sleeping car porters, as he “considered former slaves particularly appropriate candidates for jobs involving … personal service” (p. 87). Pullman allowed his workers hardly any time for sleep, and even during their short rest periods they were required [End Page 130] to remain alert to the needs of the passengers. Unlike most workers groups that focused on public safety issues, the Brotherhood of Sleeping Car Porters included the effect of exhaustion on workers’ health in its fight for better conditions. Work regulations for truckers have remained essentially unchanged since the late 1930s with ten hours on and eight hours off the job (pp. 118–19). Despite recent medical studies that show the adverse health effect of these long and often drug-enhanced shifts, governments have been reluctant to improve their situation. The book reads fluently and provides interesting details of the struggle for work-time regulations for three groups of male workers that were under great pressure to curtail their sleep time. However, it would have been helpful if these cases had been compared with the same jobs in other countries and also related to the wider context of the work-sleep dynamic in mainstream jobs in the United States. Were these examples typical or exceptional in the workplace? Were they forerunners in the fight for workers’ rights? Did sleeping car attendants in other countries experience the same conditions as the Afro-American Pullman porters, or was it the result of a uniquely paternalistic policy? The lack of any discussion in the case studies of “the cult of manly wakefulness” as a potential cause for the “overworked American” is also disappointing. Pullman sleeping car porters were told by the brotherhood to stand up for their rights and “be a man” rather than being childishly servile, but no evidence is provided that indicates that lack of sleep was viewed as a sign of manliness. For truckers, working hours were considerably...

Relationship between fatigue recovery after late-night shifts and stress relief awareness

To examine the factors related to fatigue accumulation by irregular shift workers after the late-night shift. We studied employees of a company in the transportation industry in Fukushima prefecture. The company transports passengers, and many employees, including the crew, engage in irregular shift work. We performed the investigation by using a self-administered questionnaire which was sent to 89 employees in October, 2011. Of the 89 who were given the survey, 84 replied, and 52 of those employees had worked the late-night shift (straddling midnight) at least once during September. In answer to the question "How long does it take you to recover after working the late-night-shift?" choices were "I don't feel tired ", "I recover the next day", "I recover in two or three days", and "It takes more than three days". We classified the choices into two groups of: 1) "I don't feel tired" and "I recover the next day", and 2) "I recover in two or three days" and "It takes more than three days". Other questions were asked about age, BMI, weekday average duration of sleep, whether or not a nap was taken before the late-night shift, risk of lifestyle-related diseases (hypertension, dyslipidemia, and diabetes), awareness of life stress accumulation, and exercise habits. Thirty-two employees answered that they recovered from the late-night shift by the next day, whereas 20 employees answered that it took more than 2 days to recover after the late-night-shift. The group who answered that recovery time after the late-night shift took more than 2 days significantly (p=0.035) felt that their stress management was insufficient. Age, BMI, weekday average duration of sleep, whether or not a nap was taken before the late-night shifts, risk of lifestyle-related diseases, and exercise habits showed no significant association with fatigue accumulation. The group who answered that their stress management was insufficient significantly chose liquor (p=0.045) and cigarettes (p=0.030) for stress reduction. In this study, a relationship was recognized between degree of awareness of daily stress relief and fatigue recovery period. In addition, various means of stress relief had different effects, suggesting the need for individualized mental health care.

Impacts of nurses’ circadian rhythm sleep disorders, fatigue, and depression on medication administration errors

IntroductionThe safety and quality of the administration of medications by nurses raise the opportunity to study risk factors such as circadian rhythm sleep disorders, fatigue, and depression. ObjectiveThis study was conducted to explore the extent of nurses’ circadian rhythm sleep disorders, fatigue, and depression and their impact on medication administration errors. Subjects and methodsBoth approval from the hospital ethics committee and formal patient consent were obtained. A descriptive cross sectional study was conducted using a demographic data sheet, a depression scale (CES-D), a modified fatigue severity scale, a medication errors observation sheet and an AASM two week sleep diary. ResultsThe average number of medication errors per nurse per shift was 1.40±2. “Wrong time” and “wrong rate” were the most frequent medication errors (23.1% each). About half (51.9%) of the nurses reported deficient sleep hours. Medication errors were negatively correlated with average working hours and positively correlated with depression score; errors peaked with irregular shift work patterns and irregular night sleep patterns in nurses with more than 4 night shifts in the preceding 2weeks. Fatigue was significantly correlated with total depression score and significantly associated with deficient sleep hours. Additionally, the depression score was significantly affected by irregular sleep patterns. There were significant relationships between sleep medication intake and medication errors, depression, and fatigue. Linear regression analysis demonstrated that the independent predictors of medication errors were the number of patients under the nurses’ direct care and the depression score of the nurses. ConclusionsMedication administration errors, fatigue and depression were all significantly affected by circadian sleep disorders. An administration’s control of work flow to provide convenient sleep hours will help in improving sleep circadian rhythms and consequently minimize these problems.

Other than Daytime Working Is Associated with Lower Bone Mineral Density: The Korea National Health and Nutrition Examination Survey 2009

Occupation affects bone mineral density (BMD); however, only few studies have been published. This study evaluated the effect of working time during a day on BMD. The cross-sectional study involved 18- to 50-year-old people who reported their working time and were measured for BMD using dual-energy X-ray absorptiometry in the Fourth Korea National Health and Nutrition Examination Survey 2009. The time period of work was divided into "daytime" and "other than daytime." The other-than-daytime group included evening time, nighttime, regular shift time, and irregular shift time. Among 3,005 subjects, 2,378 were daytime workers and 627 were other-than-daytime workers. The mean BMD of the total femur and lumbar spine were significantly lower in other-than-daytime workers compared to daytime workers (femur 0.948 vs. 0.966 g/cm², respectively, p = 0.001; lumbar spine 0.976 vs. 0.988 g/cm², respectively, p = 0.023). The other-than-daytime group had lower levels of serum 25-hydroxyvitamin D than the daytime group (16.3 vs. 17.6 ng/mL, p < 0.001). The proportion of osteopenia (T score < -1.0) was higher in the other-than-daytime than the daytime group (34.3 vs. 29.1 %, p = 0.014). After adjustment for age, sex, socioeconomic status, lifestyle factors, daily intake of calcium, and vitamin D level, the relative risks of osteopenia of regular-shift and irregular-shift workers were significantly higher (1.65, 95 % CI 1.05-2.60; 1.78, 95 % CI 1.09-2.89) than those of daytime workers. These data suggest that other-than-daytime working, especially regular and irregular shift working, is associated with decreased BMD and increased risk for osteopenia in Korean adults.

Association between shift work and periodontal health in a representative sample of an Asian population

The association of shift work with periodontal disease is not well known. We studied the relationship between shift work and periodontitis in a representative sample of an Asian population. Participants were 4597 full-time employees from the Fourth Korean National Health and Nutrition Examination Survey (KNHANES IV). Shifting patterns were categorized into five shifts: daytime (N=3768), evening (N=121), night (N=59), rotating (N=206), and irregular (N=443). Periodontitis was measured with the Community Periodontal Index (CPI). Confounders included age, gender, income, and education. Mediators were frequency of daily tooth brushing, regular dental check-up, smoking, alcohol consumption, diabetes, obesity, and white blood cell count. Multiple logistic regression analyses were performed to evaluate the relationship. The prevalence of periodontitis in the study population was 32.3%. Shift workers had an elevated odds ratio (OR) of periodontitis [OR 1.22, 95% confidence interval (95% CI) 1.01-1.48] after controlling for confounders. The magnitude of the association between shift work and periodontitis attenuated with adjustment of mediators (smoking and a marker of inflammation). In subgroup analyses, the association was significant (OR 1.42, 95% CI 1.03-1.95) among those ≥45 years. Irregular shift among those ≥45 years showed a significant association (OR 1.79, 95% CI 1.15-2.78). Findings of this cross-sectional study suggest that shift work may be associated with periodontitis. Shift workers aged ≥45 years and irregular shift workers aged ≥45 years were risk groups for periodontitis.

Effects of irregular-shift work and physical activity on cardiovascular risk factors in truck drivers

OBJECTIVE: To analyze the putative effect of type of shift and its interaction with leisure-time physical activity on cardiovascular risk factors in truck drivers.METHODS: A cross-sectional study was undertaken on 57 male truck drivers working at a transportation company, of whom 31 worked irregular shifts and 26 worked on the day-shift. Participants recorded their physical activity using the International Physical Activity Questionnaire along with measurements of blood pressure, body mass index and waist-hip ratio. Participants also provided a fasting blood sample for analysis of lipid-related outcomes. Data were analyzed using a factorial model which was covariate-controlled for age, smoking, work demand, control at work and social support.RESULTS: Most of the irregular-shift and day-shift workers worked more than 8 hours per day (67.7% and 73.1%, respectively). The mean duration of experience working the irregular schedule was 15.7 years. Day-shift workers had never engaged in irregular-shift work and had been working as a truck driver for 10.8 years on average. The irregular-shift drivers had lower work demand but less control compared to day-shift drivers (p &lt; 0.05). Moderately-active irregular-shift workers had higher systolic and diastolic arterial pressures (143.7 and 93.2 mmHg, respectively) than moderately-active day-shift workers (116 and 73.3 mmHg, respectively) (p &lt; 0.05) as well as higher total cholesterol concentrations (232.1 and 145 mg/dl, respectively) (p = 0.01). Irrespective of their physical activity, irregular-shift drivers had higher total cholesterol and LDL-cholesterol concentrations (211.8 and 135.7 mg/dl, respectively) than day-shift workers (161.9 and 96.7 mg/dl, respectively (ANCOVA, p &lt; 0.05).CONCLUSIONS: Truck drivers are exposed to cardiovascular risk factors due to the characteristics of the job, such as high work demand, long working hours and time in this profession, regardless of shift type or leisure-time physical activity.

Leisure-time physical activity does not fully explain the higher body mass index in irregular-shift workers

To elucidate the influence of leisure-time physical activity on body mass index (BMI), appetite-related hormones, and sleep when working irregular shifts. A cross-sectional study was undertaken of 57 male truck drivers, 31 irregular-shift workers and 26 day-shift workers. Participants completed the International Physical Activity Questionnaire and were assessed for BMI. Subjects also provided a fasting blood sample for analysis of appetite-related hormones and wore an actigraphy device for seven consecutive days. Although leisure-time physical activity (LTPA) was generally low (<150 min/week) in both groups, the irregular-shift workers were more physically active than day-shift workers (99 ± 166 vs. 23 ± 76 min/week, p < 0.01). In spite of this, mean BMI of irregular-shift workers was 2 kg/m² greater than day-shift workers (28.4 ± 3.8 vs. 26.4 ± 3.6 kg/m², p = 0.04). Mean leptin concentration was 61 % higher in irregular-shift workers (5,205 ± 4,181 vs. 3,179 ± 2,413 pg/ml, p = 0.04). Among obese individuals, irregular-shift workers had higher leptin concentration (p < 0.01) and shorter sleep duration (p = 0.01) than obese day-shift workers. Elevated BMI was associated with high leptin and low ghrelin levels in this population of irregular-shift workers. No influence of LTPA on appetite-related hormones or sleep duration was found. We conclude that moderate LTPA is insufficient to attenuate the higher BMI associated with this type of irregular-shift work in truck drivers.

Self-reported bruxism mirrors anxiety and stress in adults

Objectives: The aims were to analyze whether the levels of self-reported bruxism and anxiety associate among otherwise healthy subjects, and to investigate the independent effects of anxiety and stress experience on the probability of self-reported bruxism. Study Design: As part of a study on irregular shift work, a questionnaire was mailed to all employees of the Finnish Broadcasting Company with irregular shift work (number of subjects: n=750) and to an equal number of randomly selected employees in the same company with regular eight-hour daytime work. Results: The response rates were 82.3% (56.6 % men) and 34.3 % (46.7 % men), respectively. Among the 874 respondents, those aware of more frequent bruxism reported significantly more severe anxiety (p<0.001). Adjusted by age and gender, frequent bruxers were more than two times more likely to report severe stress (odds ratio 2.5; 95% confidence interval 1.5-4.2) and anxiety (odds ratio 2.2; 95% confidence interval 1.3-3.6) than non-or-mild bruxers. Conclusions: Present findings suggest that self-reported bruxism and psychological states such as anxiety or stress may be related in working age subjects. Key words:Bruxism, self-report, anxiety, stress, adult.

Attenuation of vagal recovery during sleep and reduction of cortisol/melatonin ratio in late afternoon associate with prolonged daytime sleepiness among media workers with irregular shift work

Media work is characterized by information flow, deadlines, and 24/7 alertness. Good recovery prevents stress-related disorders. The standardized questionnaire included items about health, health habits, sleep, work conditions, and work stress. Recordings of 24-hr heart rate variability (HRV) and four salivary samples for cortisol and melatonin levels were analyzed from 70 randomly selected workers with irregular shift work, and 70 workers with normal daytime work. Irregular shift work increased the risk of insufficient recovery when compared to normal daytime work (OR 2.0; P < 0.05). In the group of workers with insufficient subjective recovery, HRV was attenuated (P < 0.05) during the early hours of night, and cortisol/melatonin ratio was decreased (P < 0.05) in the afternoon. Physiological changes underlying subjective feelings of insufficient recovery are measurable. Attenuated HRV during sleep reflects prolonged sympathetic drive and/or impaired parasympathetic recovery. Interactions between cortisol and melatonin hormones might be involved in the development of chronic exhaustion.

Morning Cortisol Levels and Perceived Stress in Irregular Shift Workers Compared with Regular Daytime Workers

The 24/7 work environment and irregular shifts may markedly enhance the psychological pressure of media work. Changes in the hypothalamic-pituitary-adrenal axis reflect adaptation to stress. We analysed the correlation between subjective stress, sleep, salivary cortisol, and melatonin hormones among Finnish media workers with regular daytime work (RDW) and with irregular shift work (ISW) while controlling confounders. From 874 employees with regular daytime work or with irregular shift work, 70 employees from both groups were randomly selected. The final number of employees with a complete salivary cortisol profile was 66 in the RDW group and 65 in the ISW group. Five saliva samples were gathered from each subject before and during a working day. The salivary cortisol level of the sample taken 60 minutes after awakening (T1) was compared to the salivary cortisol level taken immediately after awakening (T0, T1/T0 ratio). The ratio was higher in the ISW group than in RDW group. Irregular shift work (P < 0.001), severe stress (P < 0.05), and less sleep (P < 0.05) were independently associated with an augmented cortisol response after awakening. A stressful work environment and irregular shift work enhance cortisol excretion after waking. In the long run, this may become detrimental to health.

When Does Stress End? Evidence of a Prolonged Stress Reaction in Shiftworking Truck Drivers

This study aimed to analyze individual cortisol levels in relation to work conditions, sleep, and health parameters among truck drivers working day shifts (n = 21) compared to those working irregular shifts (n = 21). A total of 42 male truck drivers (39.8 ± 6.2 yrs) completed questionnaires about sociodemographics, job content, work environment, health, and lifestyle. Rest-activity profiles were measured using actigraphy, and cardiovascular blood parameters were collected. Salivary cortisol samples were obtained: (i) at waking time, (ii) 30 min after waking, and (iii) at bedtime, during both one workday and one day off from work. Irregular-shift workers, compared to day-shift workers, showed significantly higher waist-hip ratio, very-low-density lipoprotein (VLDL) cholesterol, tiredness after work, years working as a driver, truck vibration, and less job demand (p < .05). High cortisol levels in irregular-shift workers were correlated with certain stressors, such as short sleep duration and low job satisfaction, and to metabolic parameters, such as total cholesterol, high-density lipoprotein (HDL), low-density lipoprotein (LDL), VLDL, and triglycerides. Day-shift workers had higher cortisol levels collected 30 min after waking (p = .03) and a higher cortisol awakening response (CAR; p = .02) during workdays compared to off days. Irregular-shift workers had higher cortisol levels on their off days compared to day-shift workers (p = .03). In conclusion, for the day-shift workers, a higher cortisol response was observed on workdays compared to off days. Although no direct comparisons could be made between groups for work days, on off days the irregular-shift workers had higher cortisol levels compared to day-shift workers, suggesting a prolonged stress response in the irregular-shift group. In addition, cortisol levels were correlated with stressors and metabolic parameters. Future studies are warranted to investigate further stress responses in the context of irregular work hours. (Author correspondence: crmoreno@usp.br)

CHANGES IN WORKING TIME ARRANGEMENTS OVER TIME AS A CONSEQUENCE OF WORK-FAMILY CONFLICT

Existing longitudinal studies on the relationship between working time arrangements (WTA) and work-family conflict have mainly focused on the normal causal relationship, that is, the impact of WTA on work-family conflict over time. So far, however, the reversed relationship, that is, the effect of work-family conflict on adjustments in WTA over time, has hardly been studied. Because work-family conflict is highly prevalent in the working population, further insight in this reverse relationship is invaluable to gain insight into secondary selection processes. The aim of this study is to investigate whether work-family conflict is prospectively related to adjustments in work schedules, working hours, and overtime work, and to explore sex differences and different time lags in this relation. Data of the prospective Maastricht Cohort Study were used. To study the effect of work-family conflict on a change from shift- to day work over 32 months of follow-up, male three-shift (n = 727), five-shift (n = 932), and irregular-shift (n = 451) workers were selected. To study effects of work-family conflict on reduction of working hours over 12 and 24 months of follow-up, respectively, only day workers (males and females) were selected, capturing 5809 full-time workers (≥36 h/wk) and 1387 part-time workers (<36 h/wk) at baseline. To examine effects of work-family conflict on refraining from overtime work over 12 months of follow-up, only day workers reporting frequent overtime work at baseline were selected (3145 full-time and 492 part-time workers). Cox regression analyses were performed with adjustments for age, educational level, and presence of a long-term illness. Work-family conflict was associated with a significantly increased risk of changing from shift- to day work over 32 months of follow-up in three-shift workers (relative risk [RR] = 1.77, 95% confidence interval [CI] 1.19–2.63) but not in five-shift workers (RR = 1.32, 95% CI 0.78–2.24) and irregular-shift workers (RR = 0.81, 95% CI 0.50–1.31). Within day workers, work-family conflict among full-time workers was associated with a significantly increased risk of reducing working hours during 1 yr of follow-up in women (RR = 2.80, 95% CI 1.42–5.54) but not men (RR = 1.34, 95% CI 0.81–2.22). In part-time workers, work-family conflict was associated with a significantly increased risk of reducing working hours during 1 yr of follow-up both in women (RR = 1.99, 95% CI 1.04–3.82) and men (RR = 4.03, 95% CI 1.28–12.68). Whereas the effects of work-family conflict on a reduction of working hours somewhat decreased among female full-time workers after 2 yr of follow-up (RR = 2.13, 95% CI 1.24–3.66), among male full-time workers the effects increased and reached statistical significance (RR = 1.53, 95% CI 1.05–2.21). Work-family conflict was not significantly associated with refraining from overtime work over 1 yr of follow-up. This study shows that work-family conflict has important consequences in terms of adjustments in work schedules and working hours over time, with considerable sex differences. The study thereby clearly illustrates secondary selection processes both in shift- and day workers, with significant implications for labor force participation, emphasizing the need for prevention of work-family conflict (Author correspondence: Nicole.Jansen@epid.unimaas.nl).

The unequal distribution of occupational health and safety risks among immigrants to Canada compared to Canadian-born labour market participants: 1993–2005

Objectives To examine the prevalence of occupational health and safety risk factors among immigrants to Canada compared to Canadian-born labour force participants. Methods Using data from Statistic Canada’s Survey of Labour and Income Dynamics, we examined the differential probabilities of six different occupational health and safety risks: non-membership in a union or collective bargaining agreement; employment in physically demanding occupations; employment in a workplace with less than 20 employees; regular shift work; irregular shift work; and having non-permanent employment. Our main independent variables were length of time in Canada, visible minority status, mother tongue, and location where highest level of education was attained. Models were adjusted for age, gender, education, marital status, province of residence, living in an urban or rural location, and industry group. Results Of the six occupational health and safety risks examined we found that our main independent variables describing aspects of immigration status were associated with five; the exception being irregular shift work. Adjustment for industry did not attenuate these relationships to a large extent. Conclusions Immigrants to Canada are faced with many occupational health and safety risks compared to Canadian-born respondents. These risks may be heightened among immigrants as they may not have knowledge of workplace rights and protections or have problems communicating health and safety risks or concerns. The timely provision information on occupational health and safety to immigrants before they start working should be a priority as they integrate into the Canadian labour market.

Shiftwork impacts and adaptation among health care workers

Shiftwork among health care workers impacts upon the safety and health of both employees and patients. To characterize shiftwork-related attitudes, behaviours, symptoms and coping strategies among health care workers, two validated questionnaires (the Standard Shiftwork Index and the Pressure Management Indicator) were used to identify factors predicting shiftwork adaptation. Participants (n = 376, response rate 25%) were grouped according to their work schedule (days, permanent evenings, rotating days plus evenings, permanent nights or relief and combined shifts). Indicators of lifestyle, work organization, sleep disruption, health and pressure management among workers on irregular shifts were compared with participants on day shifts, after adjustment for gender, age and marital status. Principal components analysis and ordinal logistic regression were used among irregular shiftworkers to identify factors predicting schedule adaptation. Night and relief/combined shiftworkers reported a greater ability to accommodate irregular schedules and disrupted sleep, but were also more likely to report work-related impacts than day workers. Permanent night workers generally reported poorer health, more absenteeism and less job satisfaction than day workers. Factors associated with optimal work performance or schedule contentment among shiftworkers included adequate sleep, evening circadian preference, increased age and organizational satisfaction. Reduced work performance or schedule discontent was associated with sleep/wake difficulties and poor health. This study confirmed previous research and identified factors that can be targeted for the development of more effective shiftwork adaptation programmes in a health care setting (sleep timing and duration, exercise and optimal health and organizational satisfaction).

Døgnrytmeforstyrrelser

Circadian rhythm sleep disorders often lead to sleepiness and insomnia. These disorders are characterized by a misalignment between the intrinsic circadian rhythm and the external social and physical environment. This review is based on the authors' research and clinical experience and on articles identified by non-systematic searches in Pubmed and ISI Web of Knowledge. Circadian rhythm sleep disorders are categorized into six subtypes: Delayed sleep-phase disorder, advanced sleep-phase disorder, irregular sleep-wake rhythm, free-running disorder, jet-lag and shift work disorder. By administering light and/or melatonin at appropriate times in accordance with the phase response curves of light and melatonin, most of the circadian rhythm sleep disorders can be treated effectively. The documented effects of these interventions are good, but well-controlled studies with long-term follow-up are needed. The best-documented approaches to treating circadian rhythm sleep disorders are light and melatonin; physicians can easily administer both treatments.

Bruxism and sleep efficiency measured at home with wireless devices

The present study comprised 101 (48 men) employees of the Finnish Broadcasting Company with or without irregular shift work, but all with a work week of five shifts in a row followed by 2 days off. The mean age of the subjects was 41.0 years (SD = 9.9). The BiteStrip, a single-use disposable EMG device was used for one night during the work week to detect sleep bruxism. The Actiwatch Plus actigraph was worn on the non-dominant wrist for the entire week to evaluate sleep. Total sleep time and fragmentation index, the latter as a measure of sleep efficiency was calculated for the present study. The BiteStrip scores among the participants were: 0- no bruxism: 52.2% (according to the manufacturer, comparable to a sleep laboratory bruxism count of up to 39 over 5 h), 1- mild: 29.3% (40-74 counts), 2- moderate: 12.0%: (75-124 counts) and 3- severe: 6.5% (>125 counts). Severe bruxers slept less during the work week than non-bruxers (P = 0.009), but severe bruxers slept slightly more than non-bruxers during days off. The group means of the sleep fragmentation index decreased from start towards the middle of the work week and increased during days off (P = 0.016). The levels of the fragmentation indices were consistently higher in accordance with bruxism severity (P = 0.013). It was concluded that bruxism has a coherent relationship with sleep efficiency and it can be detected at home with a low cost device.

The role of educational level and job characteristics on the health of young adults

The mediating effect of job characteristics in the socioeconomic status (SES)–health relationship has not been well studied in the young adult population. The early health trajectory is important to study since the health trajectories of young people shape their health in later years. The purpose of this study was to determine whether the education defined SES–health relationship is mediated through job characteristics, controlling for healthy lifestyle factors in young adults. We hypothesize that accounting for differences in job quality would reduce the education–health gradient. Using a sample of 10,215 Canadian workers aged 20–29 years, we used multivariable logistic regressions to examine the associations of sociodemographic, work, and lifestyle factors with two health outcomes, self-perceived health and work-related injury. The key findings indicate that job characteristics partly explain the education gradient observed in work-related injuries, and to a lesser extent in self-perceived health for working young adults. Our results show that increased physical exertion and working in sales and service or manual occupations were job characteristics which were independently associated with work-related injuries, while low work-related social support and irregular shift work were associated with poor self-perceived health. Lifestyle factors have a greater association with the education–self-perceived health relationship. This pattern of findings suggests that work factors related to education have a more specific effect on occupational health early in the health trajectory.These findings have potential practical implications since policies to reduce poor health must be targeted at appropriate age groups, as workers need to be healthy in their younger years in order to stay in the workforce as they age.

Associations of reported bruxism with insomnia and insufficient sleep symptoms among media personnel with or without irregular shift work

BackgroundThe aims were to investigate the prevalence of perceived sleep quality and insufficient sleep complaints, and to analyze whether self-reported bruxism was associated with perceptions of sleep, and awake consequences of disturbed sleep, while controlling confounding factors relative to poor sleep.MethodsA standardized questionnaire was mailed to all employees of the Finnish Broadcasting Company with irregular shift work (n = 750) and to an equal number of randomly selected controls in the same company with regular eight-hour daytime work.ResultsThe response rate in the irregular shift work group was 82.3% (56.6% men) and in the regular daytime work group 34.3% (46.7% men). Self-reported bruxism occurred frequently (often or continually) in 10.6% of all subjects. Altogether 16.8% reported difficulties initiating sleep (DIS), 43.6% disrupted sleep (DS), and 10.3% early morning awakenings (EMA). The corresponding figures for non-restorative sleep (NRS), tiredness, and sleep deprivation (SLD) were 36.2%, 26.1%, and 23.7%, respectively. According to logistic regression, female gender was a significant independent factor for all insomnia symptoms, and older age for DS and EMA. Frequent bruxism was significantly associated with DIS (p = 0.019) and DS (p = 0.021). Dissatisfaction with current work shift schedule and frequent bruxism were both significant independent factors for all variables describing insufficient sleep consequences.ConclusionSelf-reported bruxism may indicate sleep problems and their adherent awake consequences in non-patient populations.

Perceived orofacial pain and its associations with reported bruxism and insomnia symptoms in media personnel with or without irregular shift work

A standardized questionnaire was mailed to all employees of the Finnish Broadcasting Company with irregular shift work (n=750) and to an equal number of randomly selected controls in the same company with regular 8-hour daytime work. The aims were to investigate the prevalence and severity of perceived orofacial pain (Research Diagnostic Criteria for Temporomandibular Disorders Axis II) and to analyze whether current orofacial pain was associated with reported bruxism and insomnia symptoms (Diagnostic and Statistical Manual of Mental Disorders–IV and the International Classification of Sleep Disorders Revised). The response rate in the irregular shift-work group was 82.3% (56.6% men) and in the regular daytime-work group 34.3% (46.7% men). Current orofacial pain was found overall in 19.6%, of which 88.3% had experienced the pain over 6 months. All claimed that their pain fluctuated. No subjects with chronic orofacial pain reported disabling pain, and grades III and IV were not found. Insomnia symptoms and frequent bruxism were significantly more prevalent in chronic pain grade II than in lower grades. According to logistic regression, current orofacial pain was significantly positively associated with frequent bruxism (p<0.001), female gender (p<0.001), and disrupted sleep (p<0.01), and significantly negatively associated with age over 45 years (p<0.01). Our results revealed a clear-cut association between perceived orofacial pain and reported bruxism. The association held with both chronic orofacial pain intensity and current pain. Based on the multivariate analyses, it can be concluded that disrupted sleep and bruxism may be concomitantly involved in the development of orofacial pain.