The aim of the study was to investigate the differences between shiftworkers and non-shiftworkers in terms of several aspects of aging. Our interest was in particular focused on the differences observed in the assessment of subjective age, and physical, mental and social demands of work. Subjects were workers in a medical setting, 54 shiftworkers and 53 non-shiftworkers of the comparable chronological age. Subjective age measures included cognitive age, desired age and beliefs about age. The results showed that shiftworkers, compared to non-shiftworkers, reported being more physically tired by their work and that their work required more physical effort. No differences were found in reports of mental and social effort or tension produced by work. According to our data on subjective age measures, the subjects in either group felt approximately five years younger than their chronological age, desired to be ten years younger and believed that the person who is two years younger than them is most successful in its job. There were no differences between shift- and nonshiftworkers in terms of cognitive age, but shiftworkers were inclined to choose younger age as their desired age, and believed that younger people are more successful in their work.

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The objective of this study was to examine age related effects of shiftwork albeit difficult to tease apart the natural effects of aging, and lifestyle or behaviour, or job done, over time and the shifts a person works. This is an issue of concern because the numbers of shiftworkers over 45 are increasing. Participants were 306 police officers who had worked a new rota for approximately 6 months. Three age groups were compared (1=20-32.9, 2=33-39.9, 3=40+) using a range of shiftwork-related measures and multivariate analysis of covariance (controlling for shiftwork experience and other individual differences). Younger officers tended to report significantly better attitudes towards their shiftwork, better adjustment to night-bound shifts, greater job satisfaction and organisational commitment, lower fatigue and longer sleep durations. Older shiftworkers reported significantly higher morningness and lower sleep need than the younger officers. This concurred with existing research that implicates such variables in the mechanism(s) involved in age-related tolerance to shiftwork. It was also evident that the older group tended to resort to greater caffeine intake on all shifts. The findings offer tentative support for the position that age can be linked to depleted shiftwork tolerance but the issue of establishing the relative impacts of aging, lifestyle, behaviour, work type and the rota worked remains to be a challenge.

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The aim of this study was to explore the effect of a change in the speed and direction of shift rotation on the sleep and wakefulness of younger and older workers. A continuous three-shift schedule was changed from a slow backward rotating (EEE-MMMNNN- - - - -) to a fast forward rotating system (MMEENN- - - -). Sixteen subjects (mean age 42 years) were studied before and one year after the change in schedule. Two age groups were compared: ten younger men (mean age 35 years) and six older men (mean age 53 years). The effects of the new work schedule were evaluated by a questionnaire (modified SSI), and on-site registrations with an actigraph and sleep log for one shift cycle (10-15 days) before and after the new schedule. After the change in schedule, subjective sleep problems decreased and alertness increased during the morning shifts. The change in schedule influenced sleep differently in the two agegroups. Both the subjective and objective quality of sleep improved among the older workers. The results indicate that a fast forward rotating shift schedule is more suitable for older workers than a slower backward rotating system.

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Previous studies have shown that Japanese taxi drivers are exposed to more risk factors and have a higher mortality rate due to cardiovascular disease than other occupational groups. We investigated the effect of night taxi driving with a view to preventing acute events of cardiovascular disease among aged taxi drivers. Twenty-nine taxi drivers (41-67 years old) were examined for urine normetanephrine/creatinine, von Willebrand factor, anti-thrombin III, t-plasminogen activator-plasminogen activator inhibitor 1-complex, hematocrit, blood glucose and blood pressure in the morning and at midnight during a duty day and in the following morning. At the same time, the blood pressure and blood glucose of 46 taxi drivers (43-67 years old) in the morning after a night duty with little sleep and in the morning after daytime work and subsequent night sleep were compared. The results obtained indicate that the aggravation of sympathetic nervous system functions with disturbed circadian rhythms, increased blood coagulation and blood concentration, endothelial injury and the elevation of blood glucose at midnight or the next morning were induced by their night work. These conditions are supposed to favour acute vascular events in aged taxi drivers. Preventive measures considered include social support for anticoagulant food and water intake, short exercise and walking as well as taking a rest and a nap during night work.

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It is important to know whether working time schemes offer, following the adoption of the 1990 ILO Night Work Convention, a better use of the actual knowledge in moderating the adverse effects of shiftwork for both sexes. The last two national studies on a representative sample, about working conditions in France (1991, 1998), show an increase of night work among female nursing staff. Long hours of work are becoming more common for nurses. The percentage of women health care workers not working the same number of days every week increased, with work weeks of 7 days or more. Few positive aspects exist such as a reduction in the proportion of those having to work 17 Sundays or more and a reduction of shifts beginning before 7 a.m. for female nurses. New negotiations, starting in 2001, should be an opportunity for improvements.

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Differences in sleep patterns between workdays and days off contribute to shiftwork effects on workers' health and well-being. But regardless of shift schedules, female workers face more difficulties in fulfilling their sleep need because of housework. This study analyzes gender differences concerning sleep in days off by comparing sleep patterns in male and female nightworkers, analyzing sleep as related to the presence of children and testing the association of sleep features between workdays and days off. Male (n=16) and female (n=30) workers at a plastic plant, working from 10 p.m. to 6 a.m., on weekdays, filled sleep logs for seven consecutive weeks. Male and female samples did not differ in length of night sleep or in total length of sleep. For both samples, sleep length/day in days off increased, but the difference was lager among females. Also important were the relations between sleep in workdays and days off, specially among women. Among female workers, the results indicated that workers with children tended to sleep less in Saturday mornings, suggesting a negative effect of motherhood on sleep not restricted to workdays. The general results indicate that sleep need on the one hand, and social factors on the other determine the actual amount of sleep.

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This study investigated the effects of working night shifts on social and family life by examining changes in workers' daily life before and after a change in their shifts. Subjects were 40 women aged 27-59 years, working at a dish factory. During the health examination of night workers in autumn of 2000, the subjects were directly interviewed about changes in their lives induced by the shift change. Question parameters consisted of 8 items including 30 sub-items related to social and family life, such as sleep, rest, meals, sports, family time, hobbies, neighborhood association and social activities. The subjects selected one of four response categories: “becoming worse”, “no change”, “becoming better” and “difficult to determine.” With regard to the percentage of “becoming worse”, meal-related items ranked high in all of the shift types. “Family time” and “hobbies” showed high percentages in the subjects transferring from day shifts to night shifts, and in those transferring from early-morning shifts to night shifts. “Rest”, “sports” and “hobbies” showed high percentages in the subjects transferring from night shifts to midnight shifts. Decreased sleeping hours were confirmed in all of the shift types, while the subjects tended to sleep more soundly. As the workers transfer to shifts at earlier hours, they were obliged to make sacrifices in various aspects of their social and family life. Therefore, much assistance in this regard should be given to them.

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The study examined the impact of family type on the timing and duration of sleep of 16 experienced female shiftworkers working a rotating 3-shift roster. The nurses lived in one of three domestic lifestyle arrangements: single with no child care responsibilities (N=4), partnered with no child care responsibilities (N=5) and partnered with child care responsibilities (N=7). Self report sleep diaries were used to collect data over a period of 28 days, following which each nurse took part in a conversational interview. Comparisons of the roster mean sleep durations between groups show that nurses who do not have the added unwaged workload of child care, record significantly more sleep than nurses with such responsibilities. Analysis of the data by shift type shows a significant difference for afternoon shift: nurses with child care responsibilities record a significantly earlier rise time and a significantly shorter total sleep duration. The interview data further highlights how sleep patterns are related to the time constraints of both domestic and waged work.

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The purpose was to reveal the effects of stress on the parameters of cognitive performance and cardiovascular system activities in controllers working 12-hour shifts. Sixteen controllers were studied, and altogether 384 subject observations were acquired. A 5-point scale was used to estimate the perceived level of stress experienced by the controllers. Increased heart rate and heart activity-related haemodynamic parameters were found with an increase in perceived stress. Decreases found in heart rate, circulatory minute volume, and Kerdo's vegetative index over the shift became less pronounced with increased stress. Better attention was found under the average level of stress that was found on the first day shift. An effect of stress on short-term memory was not revealed. As a whole, the most pronounced changes were found during the first day shift and less pronounced changes appeared during the first night shift. Effects of stress were not found in changes of the studied parameters during the second consecutive day or night shift. Thus, increased stress causes the activation of some psychophysiological functions (attention and cardiac activity) that are indispensable for high work efficiency under increased production demands. However, the necessary activation could not be maintained during the second consecutive 12-hour shifts, probably because of accumulated fatigue, and also night work. On the other hand, too high stress may lead to the excessive activation of cardiac activity and deterioration of attention.

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Burnout is a syndrome of physical and emotional exhaustion that develops among individuals who are open to public demands. In view of their heavy work load and sleep deprivation, we decided to evaluate the impact of long working hours on burnout and psychological status among a sample of residents during the first 2 years of their residency. Seventy-eight residents participated in the study, all residents completed self administered questionnaires, and their sleep-wake cycle was monitored by a wrist-worn actigraph for a period of 5-7 days. The questionnaires included a short form suitable for Experience Sampling Method (ESM), and a longer background Questionnaire. The results revealed that sleep duration, Work Load and the interaction between them, explain the Negative Mood the day after the night shift. However, positive mood, and fatigue were not affected by sleep duration or workload. In general, after one year of residency, residents become more stressed, less involved in the job, and had a high level of burnout and psychosomatic symptoms. However, after the second year, the burnout symptoms were almost the same as at the beginning except for the level of stress that remained high. Sleep duration was unrelated to the burnout symptoms.

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This study examines the effects of supervisor support and coping on work/non-work conflict and health in shiftwork. It describes a model of shiftwork tolerance that is tested on samples from two populations of shiftworkers. The samples-of nurses and ambulance workers-differed by occupation, gender and shift schedule. Quantitative (survey questionnaire) and qualitative methods (in-depth interviews) were used to triangulate results and to yield richer data on psychosocial variables. Structural equation modelling, using EQS, was used to describe the common path relationships observed within both samples of shiftworkers. The results demonstrated important relationships between social support from supervisors, coping strategies, work/non-work conflict and symptoms that transferred robustly between the two populations of shiftworkers.

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Musculoskeletal and emotional disorders are important causes of reported diseases, causing medical absences, and eventually earlier decrease of work ability. This paper reports the results of a study carried out among practical nurses working at the Orthopedics and Trauma Institute. The objectives bf the study were: (a) to describe the routine activities performed during day and night shifts, and (b) to compare the work activities performed in different wards during these shifts. A Brazilian version of the Work Ability Index-WAI (TUOMI et a1., 1994) was answered by 83 practical nurses. Forty-three of them (52%) reported pains or musculoskeletal diseases, either based on their own opinion or diagnosed by a physician. These nurses were invited to join the second phase of the study and twenty-nine accepted it. All work activities performed in 29 shifts were observed and recorded. The results showed that day shifts were far more demanding in terms of the number of activities related to patients' care than afternoon and night shifts. Also, body postures associated with day work activities demanded important physical efforts. The number of nurses in charge during night shifts was substantially lower than during day shifts. This could lead to an overload and affect the health of the nurses.

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Although medical residents are characterized by long working hours, night shifts and high levels of work load, it is unclear if their work schedule can be classified as shift work, or if it has a similar impact on residents' well-being. The present paper compared the profile of complaints about sleep or daytime functioning of medical residents to that of rotating shift workers and day workers, of similar ages. Sixty-one residents (aged: 32.2 ± 2.2 years), after 2 years of residency, participated in the study. The two control groups with a similar age range (26-40 years) were chosen, and included 94 rotating shift workers and 146 day workers. All subjects completed self-administered questionnaires on their sleep habits, and their sleep-wake cycle was monitored by a wrist-worn actigraph. Ten percent of the residents complained about difficulties falling asleep, 34% complained about morning tiredness, 14% complained about mid-sleep awakening, and 20% about prolonged fatigue. The residents slept significantly less than the day workers, and their sleep efficiency was signiftcantly higher. When examining their subjective complaints profile, residents complained more than day workers and their answers were more similar to those of rotating shift workers, therefore they can be considered to be characterized as shift workers.

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A six-day high-carbohydrate meal (HC; 65 E% (energy percent) carbohydrates, 20 E% fat and 15 E% protein) and asix-day high-fat meal (HF; 40 E% carbohydrates, 45 E% fat and 15 E% protein) were given to seven healthy subjects in a crossover design. On the last day. subjects were kept awake for 24 hours in a metabolic laboratory while substrate utilisation and energy expenditure were measured by indirect calorimetry. The subjects were given isocaloric meals every four hours. Results showed that hunger decreased at night (F=4.2, p<0.05) and linearly increased after meal intake. Macronutrient composition (fat/carbohydrates) seemed to be of less importance for hunger. Hunger and thirst were found to be strongly associated with gastrointestinal substances, for hunger the strongest being a negative correlation with triacylglycerol (partial correlation=-0.39). It is suggested that it might not be necessary for shift workers to eat full portions at night but that satiation will occur with less food. Possibly lack of adjustment of nocturnal food intake might be one reason why overweight is common in shift work populations.

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This study was designed to investigate the effects of work schedules on the health of hospital workers at the Assistance Publique-Hôpitaux de Paris (AP-HP). Out of 40 hospitals, 17 volunteered to participate in this study. The Standard Shiftwork Index and a questionnaire concerning physicians' work schedules were used. Ten thousand questionnaires were distributed anonymously to hospital workers between March and April 1999. Professional categories comprised head nurses, nurses, nursing auxiliaries, hospital agents, midwives and full time physicians. Departments included internal and geriatric medicine, general paediatrics, orthopaedic and general surgery, operating and emergency rooms, and anaesthesiology and intensive care units. 3250 questionnaires were returned. Demographics for the respondents were: 79.2% female, average age 38.1±9.1 years old. Eleven work schedules were identified. One fourth of the personnel had fixed morning work schedules. The highest level of job satisfaction was found in personnel working in paediatrics while dissatisfaction was strongest in the gerontology and, emergency room personnel. General Health Questionnaire (GHQ) scores were high for head nurses, operating room nurses and junior doctors as well as for personnel with rotating and flexible shifts. This study will be used to make recommendations concerning the reduction of working time for French hospital workers.

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To investigate the effect of shift work on long-term sickness absence (more than 7 calendar days), an 8-year follow-up study was carried out in a factory in Japan. The participants were male employees aged 18-54 years who were engaged in manufacturing sites. Shift patterns were classified by the number of non-daytime working days during the previous one-year. The causes of sickness absence were classified into three groups, 1) causes except injury, diseases of the musculoskeletal system and connective tissue, 2) injury, 3) diseases of the musculoskeletal system and connective tissue. The analysis of long-term sickness absences was based on the first occurrence. The age-adjusted incidence of sickness absence among shift workers who were on non-daytime shifts more than two-thirds of working days during the previous one year was significantly higher than that among other workers. After adjusting for confounding factors, a significant high risk still existed for this group of workers taking sickness absence for all causes and causes except for injury and the musculoskletal disorders. These ftndings suggest that shift workers who are engaged on a particular shift schedule are more likely to take leave due to sickness.

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The General Health Questionnaire (GHQ12) and physical fitness tests were administered to 338 workers in clean rooms producing electronic parts in 12-h shifts. The results were compared to those in 95 workers in 8-h shifts and 284 daytime management, clerical and engineering workers. The 12-h shift workers complained of poor health, dissatisfaction with life and poor recuperation from fatigue more than the 8-h shift workers although the rates of complaints were highest in the daytime workers. The GHQ scores were similar in the two shift groups, and much better than those in the daytime workers. However, the 12-h shift workers showed significantly lower fitness levels than the 8-h shift workers, and the levels were even worse than the daytime workers who had higher mean age and BMI levels compared with the shift workers. The tendency to have sedentary freetime activities and larger alcohol and cigarette consumption were observed in the 12-h shift workers. The 12-h shift work may have contributed to the unhealthy behaviors resulting in lower physical fitness levels. Health promotion services at the workplace should devote greater attention to long-hour shift workers, together with devising the ways to improve working conditions and environments for reducing fatigue at work.

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The bus drivers of a public bus company, working in a fast rotating 4 shift system from 05.00 to 24.30, were examined in 1993 (230 persons) and 1999 (266 persons). The comparison between the two years showed no significant differences for all the parameters evaluated by the Standard shiftwork Index and medical examination. In both surveys work organisation was considered "efficient-fairly good" by most workers, who were mostly satisfied with their job. Work load was rated significantly higher for "afternoon" and "morning" shifts, during which most accidents at work and "in itinere" occurred. Night sleep was reduced by 3 hours on "early" shift and about 2 hours on "morning" shifts. The most prevalent health troubles dealt with low back pain, gastritis, headache and haemorrhoids. Neuroticism was the trait more correlated with poorer health conditions, whereas shiftwork exposure appeared as a significant predictor of risk of critical Effort/Reward Imbalance and minor psychological disorders. Both extrinsic and intrinsic efforts significantly increased with age, but not reward. The comparison of the same cohort of 108 persons examined both in 1993 and in 1999 showed a significant increase of low back pain, gastrointestinal troubles, haemorrhoids and lipids disorders.

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