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Results for “Work Schedule Tolerance”

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PubMed1986

Light-dark-shift stress, with special reference to spontaneous tumor incidence in female BN rats.

As a way to induce mild chronic stress, light-dark (L-D)-shift stress was applied to inbred BN virgin female rats during their whole life-span (group I, 100 animals); the incidences of spontaneous tumor and nontumor processes were recorded. A group of rats (group II, 100 animals) exposed to a standard lighting system served as the control group. Total tumors of 128 in group I and of 154 in group II were found in 74 and 86 animals, respectively. Neither were these differences nor was the pattern of spontaneous tumors statistically significant. Although in earlier studies L-D-shift stress had proved to be effective, especially with regard to its capacity to induce a substantial decrease in cellular immune response, apparently such alterations did not unfavorably affect longevity of BN female rats. Although as a side issue of this study, a strong predisposition for tumor incidence appeared to exist, in particular for the incidence of Langerhans' islet tumors, in fat animals at weaning.

Animals↗
PubMed2003

Effect of shift work on body mass index: results of a study performed in 319 glucose-tolerant men working in a Southern Italian industry.

OBJECTIVE: To examine the influence of shift work on metabolic and cardiovascular risk factors in subjects working in an industry sited in Apulia, Southern Italy. DESIGN: Cross-sectional study of metabolic effects of shift work in glucose tolerant workers in a chemical industry in southern Italy. SUBJECTS: The subjects included 319 glucose tolerant male individuals, aged 35-60 y. MEASUREMENTS: Anthropometric parameters (body mass index (BMI) and waist-to-hip ratio (WHR)), fasting concentrations of glucose, insulin, and lipids (total cholesterol, HDL-cholesterol, triglycerides), the sum of glucose levels during 75 g-oral glucose tolerance test (Sigma-OGTT), and systolic and diastolic blood pressure (SBP and DBP, respectively). RESULTS: The prevalence of obesity was higher among shift workers compared to day workers, whereas body fat distribution was not different between the two groups. Shift workers had higher BMI than day workers, and shift working was associated with BMI, independently of age and work duration. Shift workers had significantly higher SBP levels, which were independently influenced by BMI, but not by shift work, thus suggesting that the difference in SBP may well be mediated by the increased body fatness. CONCLUSION: In workers of an industry sited in Southern Italy, shift work may be directly responsible for increased body fatness and is indirectly associated with higher blood pressure levels and some features of metabolic syndrome.

Adult↗
PubMed1992

The relation of shift work tolerance to the circadian adjustment.

The amplitude and phasing of circadian rhythms are under discussion as possible predictors of tolerance to night work. In a field study, subjective sleepiness and oral temperature of 147 female nurses were measured at 2-hour intervals during a period with one morning shift and two consecutive night shifts. The nurses also filled out a questionnaire. Two types of tolerance indices were constructed: The "health index" was based on questions referring to general fatigue, gastrointestinal symptoms, and sleep disturbances, and the "sleepiness index" on the actual subjective ratings of sleepiness. According to the health index, the group with good tolerance had a larger circadian amplitude of the oral temperature rhythm on the day of the morning shift than the group with poor tolerance. However, with regard to the sleepiness index, the corresponding difference between the groups with good or poor tolerance was not significant. The data did not confirm the hypothesis that predicts a quick adjustment of the circadian rhythm when the circadian amplitude is small before the change to night work. The contradictory results found in this and in other studies do not yet permit prediction of tolerance to night work.

Adult↗
PubMed2006

Tolerance of shift work.

This study aimed to explore criteria for shift work tolerance and to investigate the relationships between personality traits and states and shift work tolerance. Eighty-nine policemen and police women completed a questionnaire, once during consecutive night shifts and again during rotating shifts, and their responses were used to assess anxiety, emotional control, positive and negative affect, health complaints, sleep quality, difficulties in social and domestic life, and perceptions about shift work. Both the criteria for tolerance and the relationship between tolerance and personality varied according to shift type. Night shift tolerance involved four factors--somatic health, flexibility, sleep and sleep need--while rotating shift tolerance involved three factors--somatic health, flexibility and fatigue. Tolerance of shift work was associated with anxiety, repressive emotional style and mood. During night shifts, anxiety was the most influential personality factor for the somatic health and sleep dimensions of shift tolerance. During rotating shifts, positive and negative moods, rather than trait personality factors, were important predictors of the somatic health and fatigue shift tolerance dimensions. These results suggest a mechanism for more effective matching of workers to suitable shift schedules.

Adult↗
PubMed1998

Guidelines for the medical surveillance of shift workers.

Occupational health physicians should evaluate workers' fitness for shift and night work before their assignment, at regular intervals, and in cases of health problems connected with night work. The evaluation should be accompanied by a careful job analysis to ensure that shift schedules are arranged according to ergonomic criteria. This arrangement can reduce health problems and make coping with irregular workhours possible, even for people suffering from contraindicative illnesses. Both health disorders representing absolute or relative contraindication and actual work conditions should be taken into account. Health checks should be aimed at detecting early signs of intolerance, such as sleeping and digestive trouble, drug consumption, accidents, and reproductive function. Their periodicity should be set in relation to specific work conditions, individual characteristics, and social factors known to influence tolerance to shift work. Shift workers should receive clear information on the possible negative effect of shift work, and also counseling for coping with shift and night work.

Counseling↗
PubMedDate not supplied

Individual differences in circadian rhythm parameters and short-term tolerance to shiftwork: a follow-up study.

The relationship between individual differences in the phase and amplitude of circadian rhythms and tolerance to shiftwork has been the subject of several studies. Those studies recorded circadian rhythms and shiftwork tolerance at approximately the same time. The present study aimed to examine the predictive relationships between the amplitude, phase, and mesor of 24 h rhythms obtained before exposure to shiftwork, and subsequent indices of tolerance measured after one and three years of shiftwork. The results revealed some stable relations between the various rhythm parameters and subsequent tolerance measures. Workers who had a higher mesor of positive moods, and a lower mesor of negative moods and fatigue, before entering shiftwork tended to tolerate shiftwork better. Further, those whose heart rate rhythm showed an earlier acrophase had better subsequent sleep quality scores, while those with a smaller amplitude of their temperature, negative mood and fatigue rhythms showed better night-shift tolerance.

Adult↗
PubMed1992

[Interindividual differences in tolerance to shift work and characteristics of shift workers: relation between the quality and duration of sleep and certain worker characteristics].

The investigation aimed at examining the relationship between the quality and duration of sleep on the one hand and various shift workers' characteristics on the other, as well as establishing whether sleep characteristics were congruent with some other indices of night shift tolerance. A total of 604 rotating shift workers working in a fast rotating shift system were administered a battery of questionnaires. The results showed that sleep quality was related to their many characteristics, especially to neuroticism, rigidity of sleeping habits, flexibility of habits, and relaxedness. Actually, the shift workers' characteristics accounted for a notable percentage (48%) of interindividual differences in sleep quality. However, there were fewer traits related to sleep duration than to sleep quality so that only a small percentage of interindividual differences in sleep duration could be explained (12-30%). Sleep quality proved to be a good indicator of night shift tolerance. The results concerning sleep duration indicated only sleep duration on the afternoon shift and days off, as well as average sleep duration in the complete shift cycle, to be relatively good indices of night shift tolerance.

Adult↗
PubMed1994

Choosing to work at night: a moderating influence on individual tolerance to shift work.

The author looked at the impact of choosing to work at night on individual tolerance to shift work. The relative importance of individual circumstances and personality type in influencing this decision was examined. Five hundred eighty-seven nurses and midwives completed measures of physical and psychological health, difficulties with sleep, social and domestic disruption, flexibility of sleeping habits, morning versus evening preferences, and reasons for engaging in shift work. Results high-lighted the advantages of choosing to work at night, rather than engaging in night work as part of a rotating-shift schedule, on tolerance to shift work. The individual circumstances of the shift workers were particularly important in influencing whether they chose to work at night. These results offer some support for the maintenance of permanent night-shift schedules and have implications for the future design of shift systems.

Adult↗
PubMed2005

[Does exogenous melatonin prove to be effective in the prevention and treatment of pathologies associated with shift and night work?].

The current data concerning the efficacy of exogenous melatonin treatment, especially with respect to night-shift workers, are presented. Therapy of sleep disorders experienced by night-shift workers is not always successful. To assess the results of melatonin therapy in shift workers, it is essential to perform extensive analyses of numerous physiological functions that may be affected by this work system as well as of possible late health effects in this group of workers. It is also necessary to establish indications and conditions for this kind of therapy. We may suspect that both night-shift work tolerance and efficacy of melatonin therapy are different in individual workers, and thus the choice of therapy should be based on a thorough examination of each worker's psycho-somatic conditions.

Adaptation, Physiological↗
PubMed1995

Effects of timed bright-light exposure on shift-work adaptation in middle-aged subjects.

Shift workers suffer from a constellation of symptoms that can severely compromise their ability to perform optimally on-shift. The largest single factor contributing to shift-worker problems is sleep disturbance, and there is little question that the primary cause of such sleep disturbance is circadian disruption. Recently, a number of studies have demonstrated that timed exposure to bright light can help facilitate adaptation to simulated shift-work schedules, at least in younger subjects. The aim of the current study was to assess the effects of bright-light interventions in middle-aged individuals undergoing a simulated shift-work regimen. Results indicate that although light was effective in resetting the circadian clocks of these subjects by more than 6 hours, there was little effect on measures of on-duty alertness and performance or on off-duty sleep. These findings suggest that middle-aged subjects may be less phase-tolerant than young subjects, and they raise questions concerning the utility of bright-light interventions in some shift-work populations.

Adult↗
PubMed1997

Aging, rhythms of physical performance, and adjustment to changes in the sleep-activity cycle.

OBJECTIVES: Shiftwork causes disturbances of the normal sleep-wake cycle and circadian rhythm. There is concern that aging workers have more problems than younger counterparts when the human body clock is disrupted. This review considers issues relating to aging, the circadian body clock, and adjustment to altered sleep-wake schedules. METHODS: Reports on effects of aging on the human body clock were reviewed. Research concerned with adjustment to circadian phase shifts (as occurs in night work) was considered. RESULTS: With aging there is an increased tendency towards morningness which is linked with difficulties in sleeping. The peak time and amplitude of normal circadian rhythms are altered. Tolerance of shiftwork can be linked with social factors as well as adaptation of the body clock. CONCLUSIONS: People habituated to night work seem to have developed mechanisms which allow them to cope with disruptions to lifestyle and the endogenous body clock. Elderly people are more suited to phase advances, as occur in morning workshifts, than to phase delays such as nocturnal work.

Adult↗
PubMed2001

Predicting shiftwork-related outcomes: shiftwork locus of control and circadian type.

This research discusses the use and viability of the shiftwork locus of control construct alongside circadian type measures as a potential predictor of shiftwork-related outcomes. The shiftwork locus of control (SHLOC) scale, measures of circadian type and shiftwork-related outcome measures were completed by 100 shiftworkers on two occasions separated by seven months. The SHLOC scale measures shiftworkers' generalised beliefs about the levels of personal control they perceive in relation to four major functional domains commonly associated with shiftwork-related disruption. These domains include: sleep, social, health and work problems. The results of multivariate regression analysis showed the SHLOC scale to be predictive of the experience of shiftwork-related sleep and social-life problems while the circadian type measures were predictive of alertness at 7 months. The results suggest that a constellation of personality factors may be an important influence on an individual's tolerance to shiftwork.

Adaptation, Psychological↗
PubMed1991

Desynchronization of oral temperature, pulse and performance circadian rhythms in shift working Indian nurses.

Circadian time structure in shift working Indian nurses was studied. In shift workers desynchronization between circadian rhythms in different physiological variables was observed. Circadian amplitudes of oral temperature, pulse and random add speed rhythms decreased significantly in shift workers as compared to control subjects. Circadian mesors of performance rhythms increased significantly in shift workers indicating that the time taken by them was more for performing the tasks. It can be concluded that the subjects studied herein are intolerant to shift work and amplitude decrement may be considered as a chronobiologic index to determine the tolerance of individual workers to shift work.

Adult↗
PubMed1991

Shiftwork: its effect on workers.

Shiftworkers have more complaints in three specific areas: sleep-wake disorders, gastrointestinal disorders, and cardiovascular disorders. After 1 to 4 months of effective shiftworking, more than 50% of shiftworkers leave shiftwork after suffering from fatigue, sleep disturbance, and other problems. In addition, older workers seem less able to adjust to shiftwork and are more likely to leave sooner. Three main factors influence the ability to predict adjustment to shiftwork: rigidity/flexibility of sleeping habits; ability/inability to overcome drowsiness; and morningness/eveningness. Occupational health nurses can influence shiftwork policy and workers' health through health promotion policies aimed at predicting which workers might be less tolerant of shiftwork, scheduling shiftwork so it follows the sun, and providing early diagnosis and rapid treatment to workers with symptoms that need management.

Absenteeism↗
PubMedDate not supplied

Determinants of shift-work adjustment for nursing staff: the critical experience of partners.

Levels of congruence between shift workers and their partners on experiences of shift work are rarely addressed. Partners, however, might be a potential source for validation of shift-work issues in terms of their understanding of these issues and might have an impact on the shift workers' experience of support or personal disruption. Participants consisted of 59 hospital shift-working nurses (55 women, 4 men) and their 59 partners. Two parallel versions of a previous questionnaire (Smith & Folkard, 1993a, 1993b) were used to obtain subjective data from workers and their partners on perceptions of the workers' experience of sleep flexibility and chronotype and lifestyle factors (sleep/fatigue, health/stress, and social/family) relating to tolerance across three shift types: day, evening, and night. All participants provided information on ideal shift choice and ratings of their own personal disruption and family, communication, and relationship issues. Results indicate that shift workers and their partners are congruent in their perceptions of the impact of shift work on the worker in all three lifestyle factors relating to tolerance across the three shift types. Shift workers experience more health/stress and social/family problems on the evening shift; this is related to their partners' increased sense of personal disruption. Similarly, when partners report the perceived impact of shift work on these same dimensions, it is associated with shift workers' heightened sense of personal disruption. Fewer sleep/fatigue and health/stress problems on the night shift are related to greater sleep flexibility, and evening types experience increased sleep/fatigue problems on the day shift. Social measures (particularly the personal disruption of the partner) rather than biological measures are the greatest predictors of shift workers' personal disruption. Findings are supported by qualitative data. It appears that the partner's understanding and own sense of disruption is critical to the experience of the shift worker regarding coping and predictability of tolerance.

Adaptation, Psychological↗
PubMed1990

Pregnancy during pediatric residency. Attitudes and complications.

Questionnaires were mailed to 116 female physicians who completed their pediatric training within the last 5 years. The questionnaire contained items focusing on (1) maternal complications, (2) health of the infant, and (3) attitudes toward the pregnancy experience. Thirty-five (38%) of the 93 respondents were pregnant during their residency. Seventeen complications occurred in 14 (36%) of the 39 pregnancies. Of the 17 complications, 6 (35%) were serious enough to require hospitalization. Complications resulted in time lost from work in 40% (15/39) of the pregnancies. When asked to describe the experience of being pregnant during residency, only 24% felt that it was "pleasant," while 52% said the experience was "tolerable" and 24% found it "miserable"! Thirty-seven percent (13/35) stated that they would not get pregnant during residency if they had it to do over again.

Attitude of Health Personnel↗
PubMed1996

A preliminary investigation into individual differences in the circadian variation of meal tolerance: effects on mood and hunger.

A forced desynchrony methodology was used to assess postprandial blood glucose in 9 female volunteers during a 3-h period following a mixed meal presented at four times of day (08:00, 14:00, 20:00, 02:00). The influence of time of day on the postmeal glucose responses was evaluated by calculating the area under the curve, largest increase, time taken to reach peak, and fasting level. Circadian variations in meal tolerance were found for the area under the curve and largest increase, responses were greater (indicating poorer meal tolerance) in the evening than the morning. Fasting blood glucose exhibited diurnal variation although in the opposite direction to meal tolerance; levels were higher in the morning than the evening. Time taken to reach peak levels was not modulated by circadian rhythmicity. Estimates of the timing of poorest meal tolerance and the magnitude of this intolerance were computed for each subject. Individual differences in the magnitude of meal intolerance were found to influence hunger and self-reported calmness. Subjects with good tolerance had rhythms in both calmness and hunger, which were not found in those with poor tolerance. Subjects with good tolerance also tended to rate themselves as feeling more calm. These mood and hunger effects may result from differences in insulin resistance, which is hypothesized to underlie the circadian variations in meal tolerance.

Adult↗