Sleep/Wake Cycle Parameters and Sleep/Fatigue Complaints in Female Night Workers

Adaptation to shift-work is influenced by the way workers schedule their lives, including allocation of sleep episodes. Female workers ( n = 29) engaged at an assembly line were studied as to individual differences in sleep parameters in order to verify whether those differences could be related to the manifestation of sleep and fatigue complaints. The sample was composed of women (20-40 y) working at night from Monday to Friday. Sleep data were based on daily sleep logs which were filled out by the workers for 10 consecutive weeks. In the analyses of sleep data both diurnal episodes between consecutive night shifts and noctural sleep episodes preceding working nights were taken into account. Worker's complaints were analyzed through questions extracted from an interview form encompassing questions on fatigue associated with the work schedule and on dissatisfaction with sleep on weekdays and weekends. The analysis of diurnal episodes showed no significant correlation between the total amount of sleep per day and the total number of complaints. Nevertheless, the latter was correlated to the length of the first sleep episode on a day, which usually began in the morning. As to sleep onset times, significant correlations were not detected concerning the first diurnal episodes. The analysis of nocturnal episodes did not reveal any significant correlation between sleep parameters and complaints. Results indicate that workers whose sleep onsets were allocated to the morning and were able to sleep for many consecutive hours, tended to show less complaints, suggesting that the temporal allocation of diurnal sleep and its length are relevant in the determination of how these workers perceive fatigue and sleep quality.     

The Amount of Diurnal Sleep,and Complaints of Fatigue and Poor Sleep,in Night-Working Women: The Effects of Having Children

This study deals with female industrial night workers. There is little scientific literature on this topic since, until recently, such shift systems have in most countries been restricted to men. The amount of diurnal sleep, as well as complaints about fatigue and poor sleep, were compared in women who were (n = 17) or were not (n = 26) caring for children. The women were engaged at an assembly line, working nights (22:00-06:00) from Monday to Friday. They filled out sleep logs for 10 consecutive weeks and were interviewed about complaints concerned with fatigue and poor sleep. A comparison of the diurnal sleeps taken between consecutive night shifts showed that the average total length of daily sleep, as well as the time of onset of the first sleep, did not differ between the groups; however, workers who had children tended to show, in comparison with their childless colleagues, more sleep episodes per day and a shorter first sleep. The total number of complaints about poor sleep and fatigue did not differ between the groups; nevertheless, workers with children complained more of difficulty in falling asleep, had a greater dissatisfaction with the amount of sleep on weekdays, and tended to show an increasing fatigue as the week progressed. We conclude that there are social pressures in women who care for children that are in addition to those that are a general consequence of night work. These results reinforce a need for the implementation of measures that organise child care, so helping a mother who wishes to work also outside the home.     

The Amount of Diurnal Sleep, and Complaints of Fatigue and Poor Sleep, in Night-Working Women: The Effects of Having Children

This study deals with female industrial night workers. There is little scientific literature on this topic since, until recently, such shift systems have in most countries been restricted to men. The amount of diurnal sleep, as well as complaints about fatigue and poor sleep, were compared in women who were (n = 17) or were not (n = 26) caring for children. The women were engaged at an assembly line, working nights (22:00-06:00) from Monday to Friday. They filled out sleep logs for 10 consecutive weeks and were interviewed about complaints concerned with fatigue and poor sleep. A comparison of the diurnal sleeps taken between consecutive night shifts showed that the average total length of daily sleep, as well as the time of onset of the first sleep, did not differ between the groups; however, workers who had children tended to show, in comparison with their childless colleagues, more sleep episodes per day and a shorter first sleep. The total number of complaints about poor sleep and fatigue did not differ between the groups; nevertheless, workers with children complained more of difficulty in falling asleep, had a greater dissatisfaction with the amount of sleep on weekdays, and tended to show an increasing fatigue as the week progressed. We conclude that there are social pressures in women who care for children that are in addition to those that are a general consequence of night work. These results reinforce a need for the implementation of measures that organise child care, so helping a mother who wishes to work also outside the home.     

Self-Reported Health and Sleep Complaints Among Nursing Personnel Working Under 12 h Night and Day Shifts

This cross-sectional exploratory study involved health care workers of various skill types and levels. We tested the hypothesis that the prevalence of diseases, sleep complaints, and insufficient time for nonprofessional activities (family, leisure, and rest) are higher among night than day workers. Data collection was carried out in two public hospitals using questionnaires and other forms. Night work was explored as a risk factor, considering a night worker as one who had at least one night job on the occasion of the research. Data were assessed by a univariate analysis. The association between work schedule and the dependent variables—health conditions, sleep complaints, and insufficient time for nonprofessional activities—was evaluated through the estimation of the prevalence ratio, with a confidence interval of 95%. Two hundred and fifty-eight female nursing personnel participated; 41.5% were moonlighters, and only 20 worked a shift of less than 12 h in length. Reports of migraine and need of medical care the 2 weeks before the survey were more prevalent among day than night workers (PR = 0.71; CI = 0.55–0.92 and PR = 0.71; CI = 0.52–0.95, respectively). Migraine headaches occurred less frequently among night than day workers as confirmed by comparing the reports of the night workers and day workers whose work history was always day shifts (PR = 0.74; CI = 0.57–0.96). Reports of mild emotional disorders (mild depression, tension, anxiety, or insomnia) were less frequent among night (PR = 0.76; CI = 0.59–0.98) and ex-night workers (PR = 0.68; CI = 0.50–0.91) than day workers who never had worked a night job. The healthy worker effect does not seem to explain the results of the comparisons between day and night workers. The possible role of exposure by day workers to some risk factors, such as stress, was suggested as an explanation for these results. No significant difference was observed between night and day workers as to sleep complaints, a result that may have been influenced by the nature of the shift-work schedule (no successive night shifts) and possibly nap taking during the night shift. Moreover, the long work hours and moonlighting of the healthcare workers, which is common in Brazil, may have masked other possible differences between the day and night workers. Among night workers, a significant relation was found between years working nights (more than 10 yrs) and high cholesterol values (PR = 2.58; CI = 1.07–6.27), a result that deserves additional study. Working nights more than four times per 2-week span was related to complaints about insufficient time for children (PR = 1.96; CI = 1.38–2.78) and rest/leisure (PR = 1.54; CI = 1.20–1.99). These results can be related to the “social value of time,” as evenings and nights are when families usually spend time together. The complexity of the professional life and the consequent heterogeneity of the group of workers under shift-work schemes confound the results. More in-depth study of the questions raised here demands a more sophisticated epidemiological treatment and larger sample size.     

Sleeping on the Job during Night Shifts May Be Associated with Extended Night Shifts and/or Variable Night Shift Onset Times

Continuous rotating shiftworkers temporarily working overtime slept at least once during the working hours of their night shifts. They worked at an electric power distribution plant in São Paulo (Brazil). In order to detect factors that could be associated with sleeping on the job, we compared those who slept (sleep group – S) with those who did not sleep (non-sleep group – NS) as to the number of night shifts, the average length of night shifts, the variability in night shift onset and offset times and the length of sleep episodes at home between consecutive night shifts. Data collection was based on dairies filled in by the workers for 30 consecutive days. For both S and NS groups, the number of night shifts for each worker varied from 5 to 9, no difference being found between groups. Individual means of night shifts length varied from 9.4 ± 0.3 hr to 14.2 ± 0.6 hr; they were significantly longer in the S than in the NS group. Night shift onset times were shown to be significantly more variable in the S than in the NS group, whereas offset times did not differ significantly between groups. Length of sleep episodes at home was not significantly different between groups. Workers who slept on the job were those who had longer working bouts and / or more variable night shift onset times. Differences among workers may be due to individual strategies to cope with a situation in which the work schedule included night shifts that were much longer than the established 8 hours, and with many changes in onset times from one night shift to the next.     

Sleep Disturbances Among Female Nurses: Comparing Shift to Day Work

Recently, attention has focused in Israel on the possible legal and health consequences of shift work. We decided to study sleep disorders among female nursing personnel working a shift schedule, in comparison with day nurses, in a large metropolitan general hospital. The study population was composed of 131 female certified nurses working shifts and 44 working days only. Inclusion criteria for the survey was at least 1 year of shift work alternating between day, evening, and night shifts, or at least 1 year of day work. All participants completed a self-report sleep questionnaire encompassing (a) demographic data, (b) sleep survey, and (c) employment details. Statistical analysis was performed using the Pearson correlation test and analysis of variance multiple range test (according to Scheffe's procedure). No significant correlation was found between sleep disorders and age of subjects. No sleep disorders were reported by 19.8% of shift workers versus 76.5% of day workers. Statistically significant findings were that the number of shifts per week >4.1 (p = 0.001) and duration of shift work >13.6 years (p = 0.007) correlated with the presence of sleep disorders. An additional significant finding (p = 0.014) was the impact of evening shifts on sleep disorders. The present small study confined to women supports the growing body of data on sleep complaints among shift workers.     

Can we consider medical residents as shift workers?

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 significantly 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.     

Study of sleep of shift workers with alternating schedules: adaptation and recovery in case of rapid shift rotation (3-4 days) (author's transl)

An electroencephalographic study of the sleep of shift workers (3 x 8) was performed in a French oil refinery. The recordings of diurnal sleep showed: a severe disorganization of the first day sleep (very short duration, decrease of PS and SWS in absolute amount); a trend towards better sleep characteristics (duration, PS and SWS amount) through the day-sleep period. Recovery night sleep appeared different when following curtailed night sleep (morning shift) and when following curtailed day sleep (night shift). Nocturnal sleep following immediately the diurnal sleep shows only partly the characteristics of a real recovery. Thus there seems to be a beginning adaptation to schedule reversal. This result supports a rapid shift alternation (3-4 days) which restrains both the cumulated sleep deficit and the adaptation to schedule reversal.     

Sleep Complaints and Polysomnographic Findings: A Study of Nuclear Power Plant Shift Workers

The literature widely recognizes that shift workers have more health complaints than the general population. The objective of this study was to describe the prevalence of sleep complaints and verify the polysomnographic (PSG) variables of shift workers in two Brazilian nuclear power plants. We carried out a subjective evaluation with a sleep questionnaire. Based on these results, the interviewees that reported sleep‐related complaints were referred for polysomnographic evaluation. Of the 327 volunteers initially evaluated by the sleep questionnaire, 113 (35%) reported sleep complaints; they were significantly older, had higher body mass index (BMI), and worked more years on shifts than those without sleep complaints. Of these 113, 90 met criteria for various sleep disorders: 30 (9%) showed obstructive sleep apnea (OSA), 18 (5.5%) showed limb movement, and 42 (13%) evidenced both sleep problems and had a significantly higher proportion of sleep stage 1 and arousals compared with the 23 shift workers that had no indices of sleep problems. The present study found that 90 (27.5%) of the evaluated participants met the PSG criteria of some type of clinical sleep disorder. This high proportion should be investigated for associations with other aspects of work, such as working hours, working schedule, years performing shift work, and access to health services. Due to the strong association between sleep disorders and the incidence of fatigue and sleepiness, the evaluation of the sleep patterns and complaints of shift workers is essential and should be considered to be one of the basic strategies of industry to prevent accidents.     

Sleep complaints and polysomnographic findings: a study of nuclear power plant shift workers

The literature widely recognizes that shift workers have more health complaints than the general population. The objective of this study was to describe the prevalence of sleep complaints and verify the polysomnographic (PSG) variables of shift workers in two Brazilian nuclear power plants. We carried out a subjective evaluation with a sleep questionnaire. Based on these results, the interviewees that reported sleep-related complaints were referred for polysomnographic evaluation. Of the 327 volunteers initially evaluated by the sleep questionnaire, 113 (35%) reported sleep complaints; they were significantly older, had higher body mass index (BMI), and worked more years on shifts than those without sleep complaints. Of these 113, 90 met criteria for various sleep disorders: 30 (9%) showed obstructive sleep apnea (OSA), 18 (5.5%) showed limb movement, and 42 (13%) evidenced both sleep problems and had a significantly higher proportion of sleep stage 1 and arousals compared with the 23 shift workers that had no indices of sleep problems. The present study found that 90 (27.5%) of the evaluated participants met the PSG criteria of some type of clinical sleep disorder. This high proportion should be investigated for associations with other aspects of work, such as working hours, working schedule, years performing shift work, and access to health services. Due to the strong association between sleep disorders and the incidence of fatigue and sleepiness, the evaluation of the sleep patterns and complaints of shift workers is essential and should be considered to be one of the basic strategies of industry to prevent accidents.     

Sleep, sleepiness, fatigue, and performance of 12-hour-shift nurses

Nurses working 12-h shifts complain of fatigue and insufficient/poor-quality sleep. Objectively measured sleep times have not been often reported. This study describes sleep, sleepiness, fatigue, and neurobehavioral performance over three consecutive 12-h (day and night) shifts for hospital registered nurses. Sleep (actigraphy), sleepiness (Karolinska Sleepiness Scale [KSS]), and vigilance (Performance Vigilance Task [PVT]), were measured serially in 80 registered nurses (RNs). Occupational fatigue (Occupational Fatigue Exhaustion Recovery Scale [OFER]) was assessed at baseline. Sleep was short (mean 5.5?h) between shifts, with little difference between day shift (5.7?h) and night shift (5.4?h). Sleepiness scores were low overall (3 on a 1-9 scale, with higher score indicating greater sleepiness), with 45% of nurses having high level of sleepiness (score >?7) on at least one shift. Nurses were progressively sleepier each shift, and night nurses were sleepier toward the end of the shift compared to the beginning. There was extensive caffeine use, presumably to preserve or improve alertness. Fatigue was high in one-third of nurses, with intershift fatigue (not feeling recovered from previous shift at the start of the next shift) being most prominent. There were no statistically significant differences in mean reaction time between day/night shift, consecutive work shift, and time into shift. Lapsing was traitlike, with rare (39% of sample), moderate (53%), and frequent (8%) lapsers. Nurses accrue a considerable sleep debt while working successive 12-h shifts with accompanying fatigue and sleepiness. Certain nurses appear more vulnerable to sleep loss than others, as measured by attention lapses.     

The Relationship between Sleep and Shift System, Age and Chronotype in Shift Workers

The purpose of this study was to investigate the effects of shift system, age, and chronotype on the sleep habits, sleepiness and catnaps of shift workers during night work. We administrated a Morningness-Eveningness Questionnaire and Life Habits Inventory to 561 male shift workers of three different shift systems in Korea. The mean scores on the Morningness-Eveningness Questionnaire clearly shifted toward the Morning type from the young to old groups. The waking and bedtimes during the day and evening shift were earlier for the older than for the younger groups, and these times were earlier across the Evening, Intermediate, to Morning type as well. Sleep length during the day shift was longer from the young to old, and it was shorter from the Evening, Intermediate, to Morning type. In the weekly rotation full-day 3-team 3-shift system and continuous full-day 3-team 3-shift system (which had earlier starting times for day shift) the sleep length of the younger workers was short. For the aged workers, sleep length during the night shift was short because they woke up early. In the weekly rotation full-day 2-team 2-shift system that had a short working interval, the reduction of sleep length during night shift was greater than that of the other shift systems. However, the scores on the Morningness-Eveningness Questionnaire showed a significantly negative correlation only in the bedtime during day shift among the sleep habit parameters for the independent variable by age. For the percentage of subjects that reported 'become sleepiness', the degree and time of sleepiness during the night shift were greater and earlier for the older than for the younger workers, and greater for the Morning than for the Evening type. The percentage of subjects who took a catnap during night shift, as well as the length of their catnap, were also higher and longer for the older groups, and higher and longer for the Morning type than for the Evening type. From these results, we surmised that the sleep habit parameters were influenced the age or shift systems rather than the chronotype. The sleep length during the night shift was shorter for the aged than for the young. In the shift systems that have a short working interval, the nocturnal was remarkably shorter for the young than the aged. The aged had not adapted their sleep for the night shift compared to the young, this suggested by the aged's strong complaint of sleepiness and by the fact that a larger percentage of aged subjects said they took catnaps during night shift compared to the younger workers.     

Self-reported health and sleep complaints among nursing personnel working under 12 h night and day shifts

This cross-sectional exploratory study involved health care workers of various skill types and levels. We tested the hypothesis that the prevalence of diseases, sleep complaints, and insufficient time for nonprofessional activities (family, leisure, and rest) are higher among night than day workers. Data collection was carried out in two public hospitals using questionnaires and other forms. Night work was explored as a risk factor, considering a night worker as one who had at least one night job on the occasion of the research. Data were assessed by a univariate analysis. The association between work schedule and the dependent variables—health conditions, sleep complaints, and insufficient time for nonprofessional activities—was evaluated through the estimation of the prevalence ratio, with a confidence interval of 95%. Two hundred and fifty-eight female nursing personnel participated; 41.5% were moonlighters, and only 20 worked a shift of less than 12 h in length. Reports of migraine and need of medical care the 2 weeks before the survey were more prevalent among day than night workers (PR = 0.71; CI = 0.55-0.92 and PR = 0.71; CI = 0.52-0.95, respectively). Migraine headaches occurred less frequently among night than day workers as confirmed by comparing the reports of the night workers and day workers whose work history was always day shifts (PR = 0.74; CI = 0.57-0.96). Reports of mild emotional disorders (mild depression, tension, anxiety, or insomnia) were less frequent among night (PR = 0.76; CI = 0.59-0.98) and ex-night workers (PR = 0.68; CI = 0.50-0.91) than day workers who never had worked a night job. The healthy worker effect does not seem to explain the results of the comparisons between day and night workers. The possible role of exposure by day workers to some risk factors, such as stress, was suggested as an explanation for these results. No significant difference was observed between night and day workers as to sleep complaints, a result that may have been influenced by the nature of the shift-work schedule (no successive night shifts) and possibly nap taking during the night shift. Moreover, the long work hours and moonlighting of the healthcare workers, which is common in Brazil, may have masked other possible differences between the day and night workers. Among night workers, a significant relation was found between years working nights (more than 10 yrs) and high cholesterol values (PR = 2.58; CI = 1.07-6.27), a result that deserves additional study. Working nights more than four times per 2-week span was related to complaints about insufficient time for children (PR = 1.96; CI = 1.38-2.78) and rest/leisure (PR = 1.54; CI = 1.20-1.99). These results can be related to the “social value of time,” as evenings and nights are when families usually spend time together. The complexity of the professional life and the consequent heterogeneity of the group of workers under shift-work schemes confound the results. More in-depth study of the questions raised here demands a more sophisticated epidemiological treatment and larger sample size.     

Sleep Loss and Performance of Anaesthesia Trainees and Specialists

Fatigue risk associated with work schedules of hospital doctors is coming under increasing scrutiny, with much of the research and regulatory focus on trainees. However, provision of 24 h services involves both trainees and specialists, who have different but interdependent work patterns. This study examined work patterns, sleep (actigraphy, diaries) and performance (psychomotor vigilance task pre‐ and post‐duty) of 28 anaesthesia trainees and 20 specialists across a two‐week work cycle in two urban public hospitals. Trainees at one hospital worked back‐to‐back 12 h shifts, while the others usually worked 9 h day shifts but periodically worked a 14 h day (08:00–22:00 h) to maintain cover until arrival of the night shift (10 h). On 11% of day shifts and 23% of night shifts, trainees were working with ≥2 h of acute sleep loss. However, average sleep loss was not greater on night shifts, possibly because workload at night in one hospital often permitted some sleep. Post‐night shift performance was worse than post‐day shift performance for the median (t₍₁₃₁₎=3.57, p<0.001) and slowest 10% of reaction times (t₍₁₃₄₎=2.91, p<0.01). At the end of night shifts, poorer performance was associated with longer shift length, longer time since waking, greater acute sleep loss, and more total work in the past 24 h. Specialists at both hospitals had scheduled clinical duties during the day and were periodically scheduled on call to cover after‐hours services. On 8% of day shifts and 14% of day+call schedules, specialists were working with ≥2 h of acute sleep loss. They averaged 0.6 h less sleep when working day shifts (t_(23.5)=2.66, p=0.014) and 0.8 h less sleep when working day shifts+call schedules (t_(26.3)=2.65, p=0.013) than on days off. Post‐duty reaction times slowed linearly across consecutive duty days (median reaction time, t₍₁₃₁₎=?3.38, p<0.001; slowest 10%, t₍₁₆₀₎=?3.33, p<0.01; fastest 10%, t₍₁₃₈₎=?2.67, p<0.01). Poorer post‐duty performance was associated with greater acute sleep loss and longer time since waking, but better performance was associated with longer day shifts, consistent with circadian improvement in psychomotor performance across the waking day. This appears to be the first study to document sleep loss among specialist anaesthetists. Consistent with observations from experimental studies, the sleep loss of specialists across 12 consecutive working days was associated with a progressive decline in post‐duty PVT performance. However, this decline occurred with much less sleep restriction (< 1 h per day) than in laboratory studies, suggesting an exacerbating effect of extended wakefulness and/or cumulative fatigue associated with work demands. For both trainees and specialists, robust circadian variation in PVT performance was evident in this complex work setting, despite the potential confounds of variable shift durations and workloads. The relationship between PVT performance of an individual and the safe administration of anaesthesia in the operating theater is unknown. Nevertheless, the findings reinforce that any schedule changes to reduce work‐related fatigue need to consider circadian performance variation and the potential transfer of workload and fatigue risk between trainees and specialists.     

The Relationship between Sleep and Shift System,Age and Chronotype in Shift Workers

The purpose of this study was to investigate the effects of shift system, age, and chronotype on the sleep habits, sleepiness and catnaps of shift workers during night work. We administrated a Morningness-Eveningness Questionnaire and Life Habits Inventory to 561 male shift workers of three different shift systems in Korea. The mean scores on the Morningness-Eveningness Questionnaire clearly shifted toward the Morning type from the young to old groups. The waking and bedtimes during the day and evening shift were earlier for the older than for the younger groups, and these times were earlier across the Evening, Intermediate, to Morning type as well. Sleep length during the day shift was longer from the young to old, and it was shorter from the Evening, Intermediate, to Morning type. In the weekly rotation full-day 3-team 3-shift system and continuous full-day 3-team 3-shift system (which had earlier starting times for day shift) the sleep length of the younger workers was short. For the aged workers, sleep length during the night shift was short because they woke up early. In the weekly rotation full-day 2-team 2-shift system that had a short working interval, the reduction of sleep length during night shift was greater than that of the other shift systems. However, the scores on the Morningness-Eveningness Questionnaire showed a significantly negative correlation only in the bedtime during day shift among the sleep habit parameters for the independent variable by age. For the percentage of subjects that reported 'become sleepiness', the degree and time of sleepiness during the night shift were greater and earlier for the older than for the younger workers, and greater for the Morning than for the Evening type. The percentage of subjects who took a catnap during night shift, as well as the length of their catnap, were also higher and longer for the older groups, and higher and longer for the Morning type than for the Evening type. From these results, we surmised that the sleep habit parameters were influenced the age or shift systems rather than the chronotype. The sleep length during the night shift was shorter for the aged than for the young. In the shift systems that have a short working interval, the nocturnal was remarkably shorter for the young than the aged. The aged had not adapted their sleep for the night shift compared to the young, this suggested by the aged's strong complaint of sleepiness and by the fact that a larger percentage of aged subjects said they took catnaps during night shift compared to the younger workers.     

Sleep parameters among offshore workers: an initial assessment in the Campos Basin, Rio De Janeiro, Brazil

Shift work has potentially adverse effects on health, particularly on sleep. The purpose of the present study was to assess sleep parameters among personnel working in oil and gas offshore installations in the Campos Basin, Rio de Janeiro, Brazil. One hundred and seventy-nine subjects were asked to complete a sleep questionnaire with multiple-choice answers. Offshore workers were divided into two groups according to their work schedule: (1) fixed daytime workers (n = 86; age: 35.8+/-9.6 yrs) and (2) shift (n = 87) or night (n = 6) workers (total n = 93; age: 37.7+/-9.7 yrs). Shift/night workers reported poor sleep more frequently than the daytime workers (20.4% vs. 1.2%, p < 0.01), as well as habitual difficulty in falling asleep (15.1% vs. 4.7%, p<0.01), long latency of sleep onset (28% vs. 7%, p<0.01), fragmented sleep (45.2% vs. 16.3%, p<0.01), short sleep episodes (44.1% vs. 16.3%, p < 0.01), irregular bedtimes (29.0% vs. 12.8%, p < 0.01), and feeling tired upon awakening (15.1% vs. 3.5%, p < 0.01). Habitual napping and loud snoring were reported twice as often in shift/night than in day workers (p < 0.01). Nightmares, somnambulism, and unpleasant feeling in the legs were equality reported by both groups (p > 0.05). Few offshore workers had sought medical help for their sleep problems. A higher number of shift/night workers reported feelings of sadness compared with day workers (26.9% vs. 9.3%, p < 0.01). The findings of this study show that subjective reports of sleep-related problems are quite common among Brazilian offshore shift workers. Reliance on self-reported sleep problems and a cross-sectional design are the main limitations of our study.     

Sleep on the job partially compensates for sleep loss in night-shift nurses

Nursing personnel in Brazil are usually submitted to fixed 12 h shifts with no consecutive working days or nights. Moonlighting is common in this group, with a consequent increase in the number of working hours. The possibility of sleeping on the job during the night shift in the studied hospitals had already been described. The present study aims to analyze whether the time devoted to daily activities (sleep, rest, leisure, housework, commuting, personal needs, care of children or other people, non-paid work, and study) is related to the number of worked hours and to nap-taking during the night shift. The field study took place at two public hospitals in Rio de Janeiro, Brazil. Workers filled out a structured form on time devoted to the above-mentioned activities for at least four consecutive days. The time devoted to sleep was analyzed according to its occurrence at home or on the job. Workers were classified according to the number of jobs (one job/two jobs) and the time dedicated to work according to the median of the whole series (below the median/above the median). All workers who had at least one working night were analyzed as to nap-taking on the job. They were classified according to the sleep occurrence during the night shift-the sleep group and the non-sleep group, both of which were compared to daytime workers. Statistical treatment of data included non-parametrical procedures. The study group comprised 144 workers (mean age: 35.7+/-10.5 years old; 91% women; 78% nurse assistants, the remainder registered nurses). They recorded their daily activities for 4-11 days; 829 cumulative days were analyzed for the whole group. A total of 165 working nights were analyzed; sleep or rest occurred during 112 (68%) of them, with mean sleep/rest duration of 141+/-86 min. Time devoted to sleep and leisure varied according to the number of working hours, being significantly reduced in those submitted to longer work hours (p < 0.001 and p = 0.002, respectively). Results close to significance point to a reduction in the time dedicated to housework among workers with long work hours (p = 0.053). The time spent on sleep/rest per working night did not differ according to the number of worked hours (p = 0.490). A tendency was observed for those who have two jobs to devote more time to sleep/rest on the job (p = 0.058). The time of personal needs was significantly lower among those who did not sleep on the job as compared to day workers (p = 0.036). The total sleep time was significantly lower among those who did not sleep on the job, as compared to day workers and to those who slept on the job (p = 0.004 and p = 0.05, respectively). As to home sleep length, workers who slept and those who did not sleep on the job were similar and slept significantly less than exclusively daytime workers (p < 0.001 and p = 0.002, respectively). Sleeping on the job during the night shift seems to partially compensate for the shorter sleep at home among night workers and may play a beneficial effect in coping with two jobs.     

Photic Resetting in Night-Shift Work: Impact on Nurses' Sleep

The objective of this study was to quantify daytime sleep in night-shift workers with and without an intervention designed to recover the normal relationship between the endogenous circadian pacemaker and the sleep/wake cycle. Workers of the treatment group received intermittent exposure to full-spectrum bright light during night shifts and wore dark goggles during the morning commute home. All workers maintained stable 8-h daytime sleep/darkness schedules. The authors found that workers of the treatment group had daytime sleep episodes that lasted 7.1?±?.1?h (mean?±?SEM) versus 6.6?±?.2?h for workers in the control group (p?=?.04). The increase in total sleep time co-occurred with a larger proportion of the melatonin secretory episode during daytime sleep in workers of the treatment group. The results of this study showed reestablishment of a phase angle that is comparable to that observed on a day-oriented schedule favors longer daytime sleep episodes in night-shift workers. (Author correspondence: diane.boivin@douglas.mcgill.ca)     

Working hours and fatigue of Japanese flight attendants (FA).

There have been some reports concerning high complaint rates of fatigue or fatigue-related symptoms including lower back pain in flight attendants (FA). Thus, the relations of working conditions with work stress and fatigue symptoms were studied chiefly by focusing on working hours. From analysis of the time-table and fatigue symptoms of workers on international flights, it was suspected that there were some work-related factors jointly causing serious FA fatigue symptoms; night time and early morning work, long flight hours and a large time difference, thus disturbing their biological rhythms. On domestic flights, showing up early in the morning and debriefing late in the night were often observed together with a highly irregular FA time schedule. By statistical analyses, some factors including long working hours, frequent landing and late debriefing hours were considered to contribute significantly to the high fatigue complaint rates. Thus, it should be emphasized that many countermeasures are necessary to improve FA working conditions including working hours, rest on the airplane (ONO et al., 1990) and sleep during layover, in order to reduce their work stress and fatigue symptoms.     

Adaptation to night shifts and synchronisation processes of night workers

Human beings are accustomed to being active and awake during the day, and asleep and rest at night. Since we live in a society which is organised predominantly along daytime activity, therefore working in the night shift may deeply disrupt our social and family life. It is also a well-known fact that night shift causes fatigue and circadian disruption. The basic manifestation of fatigue and circadian rhythm has been linked to health and safety problems, involving decrements in psychophysical and physiological functions, plus subjective complaints. In this context quantitative relationships between shift work and circadian rhythm need to be assessed to explore suitable time schedule, and to minimise sleep depth and fatigue. There is also a great need to discuss circadian disruption, sleepiness and the increasing cost of work related illness among night workers. In this regard, some aspects of fatigue and circadian disruption caused from night shift work are revealed in this paper aiming to increase workers' health, safety and well being as well as productivity. Light/dark cycle and social stimuli issues acting on the circadian timing systems are also explored to solicit opinions and discussion on the controversy of night work. Suggestions are therefore likewise given to enhance workers' adaptation to night shift and synchronization process.