Rethinking work and its organisation through the lens of William Morris

In this study we examine sleep during adaptation and readaptation to different shift work schedules in the offshore oil industry. The sleep of 19 offshore workers was assessed daily for 1 week before, during the work period, and for 1 week after 3 different work schedules: (1) day (14 consecutive days of work), (2) night (14 consecutive nights of work), and (3) swing shift work (first 7 nights with night work then 7 days of day work). The workers' sleep was assessed for 84 days. Actigraphy and sleep diary estimates of sleep was applied assessing: (1) adaptation to offshore shift work, (2) sleep across the 2 offshore work weeks, and (3) readaptation after the work period. Regarding adaptation, sleep efficiency was higher when working day than night and swing shift the first week of work. Sleep quality was better during swing than regular day/night shifts the first week of work. Total sleep time was longer during day and night shift than swing shift across the 2 work weeks. Sleep efficiency, based on sleep diaries, was higher during day than night and swing shift during the 2 work weeks. There were no significant differences between the shifts in readaptation in terms of sleep. To conclude, adaptation to swing shift was more difficult than adaptation to regular day and night shifts in terms of sleep. Readaptation to day work after 1 week of night work affected sleep negatively. There were no differences between the shift schedules the week after the work period.

A questionnaire was designed to assess the following: why working people chose to eat or not to eat at a particular time of day; the factors that influenced the type of food eaten; and subjective responses to the meal (hunger before, enjoyment during, satiety afterward). Self-assessments were done every 3h during a typical week containing work and rest days, by one group of 50 day workers and another group of 43 night workers. During the night work hours compared to rest days, night workers evidenced a significantly altered food intake, with a greater frequency of cold rather than hot food (p < 0.001). The type and frequency of meals were influenced significantly more (p < 0.05) by habit and time availability and less by appetite. This pattern continued into the hours immediately after the night shift had ended. In day workers food intake during work hours, compared to rest days, was also influenced significantly more often (p < 0.05) by time availability than hunger, but less so than with night workers. Moreover, day workers were less dependent than night workers upon snacks (p = 0.01), and any significant differences from rest days did not continue beyond work hours. Not only did night workers change their eating habits during work days more than did day workers but also they looked forward to their meals significantly less (p < 0.001) and felt more bloated after consuming them (p < 0.05), such effects being present to some extent during their rest days also. These findings have clear implications for measures designed to ease eating problems that are commonly problematic in night workers.

Introduction Sleep deficiencies are common in nurses, with up to 89% of nurses working some form of shiftwork (i.e., working before 6am and/or after 9pm). It is estimated that approximately 34% of nurses report insomnia disorder and 14% report shift work sleep disorder. Nurses face unique physical, psychological, and occupational demands that disrupt their sleep quality and duration and may conflict with their natural circadian rhythm. Methods Nurses (N = 26, 88% female, 80% white, mean age = 36.16 years, SD = 8.56) were asked to wear an Actiwatch to measure objective sleep parameters, a daily adhesive sweat collection patch, provide two blood samples (at Day 1 and Day 7), and report daily subjective sleep parameters (total sleep time, sleep onset latency, wake after sleep onset, and sleep efficiency) via the Consensus Sleep Diary for 7 days. The sample was further divided into day shift (n = 14) and night shift (n = 12) nurses. Data collection and cleaning are ongoing and preliminary results of complete sleep diary data are presented. Results Results of the independent sample t tests suggest that total sleep time was significantly different on days on shift versus off shift (t(86) = 2.94, p = .002) for day shift nurses but not for night shift nurses (t(76) = .48, p = .317). There was no difference in total sleep time between day and night shift workers. Additional exploratory analyses will be completed by the conference, comparing additional parameters (e.g., timing) in individual sleep periods (i.e., 1st work day, 2nd work day; 1st off day, 2nd off day) both within (night &amp; day shift), as well as between (night vs day shift) groups on the final sample (N=40; 20 day and 20 night shift). Conclusion The results may indicate that day shift nurses have more variable sleep than night shift nurses. Further analyses will help fill gaps in our understanding of the deficient (i.e., inadequate, interrupted, mistimed) sleep in nurses (i.e., within and between day and night working), as well as inform potential interventions (i.e., CBTI for shift workers) to improve the sleep of critical nursing staff. Support (if any)

Objectives Evidence of an effect of shift work on all-cause and cause-specific mortality is inconsistent. This study aims to examine whether shift work is associated with increased all-cause and cause-specific mortality. Methods We linked 28 731 female nurses (age ≥44 years), recruited in 1993 or 1999 from the Danish nurse cohort where they reported information on shift work (night, evening, rotating, or day), to the Danish Register of Causes of Death to identify deaths up to 2013. We used Cox regression models with age as the underlying scale to examine the associations between night, evening, and rotating shift work (compared to day shift work) and all-cause and cause-specific mortality in models adjusted for potentially confounding variables. Results Of 18 015 nurses included in this study, 1616 died during the study time period from the following causes: cardiovascular disease (N=217), cancer (N= 945), diabetes (N=20), Alzheimer's disease or dementia (N=33), and psychiatric diseases (N=67). We found that working night [hazard ratio (HR) 1.26, 95% confidence interval 95% CI) 1.05-1.51] or evening (HR 1.29, 95% CI 1.11-1.49) shifts was associated with a significant increase in all-cause mortality when compared to working day shift. We found a significant association of night shift work with cardiovascular disease (HR 1.71, 95% CI 1.09-2.69) and diabetes (HR 12.0, 95% CI 3.17-45.2, based on 8 cases) and none with overall cancer mortality (HR 1.05, 95% CI 0.81-1.35) or mortality from psychiatric diseases (HR 1.17, 95% CI 0.47-2.92). Finally, we found strong association between evening (HR 4.28, 95% CI 1.62-11.3) and rotating (HR 5.39, 95% CI 2.35-12.3) shift work and mortality from Alzheimer's disease and dementia (based on 8 and 14 deaths among evening and rotating shift workers, respectively). Conclusions Women working night and evening shifts have increased all-cause, cardiovascular, diabetes, and Alzheimer's and dementia mortality.

Working hours and cardiovascular disease.

The purpose of this study was to determine whether a short period (5 days) of night-shift work affected the pituitary-adrenal responses to CRH. Ten nurses (8 female and 2 male; age 28.1 +/- 1.7 yr: mean +/- SEM) working at the Royal Liverpool University Hospital, and who regularly undertook periods of night and day shift work were enrolled. Measurements were made of basal ACTH and cortisol concentrations, and their responses to iv ovine CRH (1 microgram.kg-1). Basal ACTH concentrations were higher during the night shift than during the day shift (12.9 +/- 5.1 pmol.L-1 vs. 4.7 +/- 1.2 pmol.L-1, P < 0.01) whereas cortisol concentrations were lower (551 +/- 48 nmol.L - 1 vs. 871 +/- 132 nmol.L - 1, P < 0.01). After CRH injection, ACTH concentrations remained consistently higher during the night shift, but the integrated increase in ACTH concentration was lower (P < 0.05) than during the day shift. Conversely, the increase in cortisol concentration was greater during the night shift than the day shift (283 +/- 53 nmol.L-1 vs. 134 +/- 41 nmol.L-1, P < 0.05). We conclude that the pituitary-adrenal responses to CRH are markedly disrupted after only 5 days of nighttime work. These abnormalities mimic those previously observed in patients with chronic fatigue syndrome. Neuroendocrine abnormalities reported to be characteristic of chronic fatigue syndrome may be merely the consequence of disrupted sleep and social routine.

Leese, Graham; Chattington, Paula; Fraser, William; Vora, Jiten; Edwards, Richard; Williams, Gareth Author Information

In young hospital nurses being exposed to a night shift work schedule for the first time in their occupational life, sleep quality is investigated quantitatively. A main sleep period and supplementary sleep periods were defined and analyzed to investigate sleep behavior and quality. A total of 30 young nurses (26 women, 4 men), mean age 20.2 +/- 2.1 years participated. A 3 week nursing school period was followed by a 3 week work period with a 3-5 night shift sub-period and recovery days. Sleep-wake behavior was assessed with an actigraph, sleep diaries, Epworth sleepiness scale (ESS), and quality of life was assessed with a standard questionnaire (SF-36). Comparing the school period with the work shift period when excluding recovery days after night shift period significant increase of total sleep time within 24 h was found during the work days (ANOVA P < 0.05). During the night shift sub-period, there was just a small decline of the main sleep period at day (n.s.) which was not compensated by supplementary sleep episodes. The supplementary sleep during work day varied between 11 min (school period) and 18 min after recovery days from night shift (n.s.). Young healthy nurses tolerate the first night shift exposure very well, according to objective and subjective parameters related to quality of sleep. An increased sleep need during work days lead to longer total sleep time, but do not lead to longer supplementary sleep episodes. Young nurses tolerate the first rotating shift period and the first night shift period very well.

Decreased melatonin production, due to nighttime exposure to light, has been proposed as one of the physiological mechanisms increasing cancer risk in night workers. However, few studies measured melatonin production in night workers, and most of these studies did not measure melatonin over 24 h. One study compared total melatonin production between day and night shifts in rotating night workers and did not find significant differences. However, without baseline measures, it was not possible to exclude that melatonin production was reduced during both day and night work. Here, we used data collected in a simulation study of night work to determine the effect of night work on both nighttime and 24-h melatonin production, during three consecutive days of simulated night work. Thirty-eight healthy subjects (15 men, 23 women; 26.6 ± 4.2 years) participated in a 6-d laboratory study. Circadian phase assessments were made with salivary dim light melatonin onset (DLMO) on the first and last days. Simulated day work (09:00–17:00 h) occurred on the second day, followed by three consecutive days of simulated night work (00:00–08:00 h). Light intensity at eye level was set at 50 lux during both simulated day and night work. The subjects were divided into three matched groups exposed to specific daytime light profiles that produced various degrees of circadian phase delays and phase advances. Melatonin production was estimated with the excretion of urinary 6-sulfatoxymelatonin (aMT6s). For the entire protocol, urine was collected every 2 h, except for the sleep episodes when the interval was 8 h. The aMT6s concentration in each sample was multiplied by the urine volume and then added to obtain total aMT6s excretion during nighttime (00:00–08:00 h) and during each 24-h day (00:00–00:00 h). The results showed that melatonin production progressively decreased over consecutive days of simulated night work, both during nighttime and over the 24 h. This decrease was larger in women using oral contraceptives. There was no difference between the three groups, and the magnitude of the decrease in melatonin production for nighttime and for the 24 h was not associated with the magnitude of the absolute circadian phase shift. As light intensity was relatively low and because the decrease in melatonin production was progressive, direct suppression by nighttime light exposure was probably not a significant factor. However, according to previous experimental observations, the decrease in melatonin production most likely reflects the circadian disruption associated with the process of re-entrainment. It remains to be determined whether reduced melatonin production can be harmful by itself, but long-term and repeated circadian disruption most probably is.

ABSTRACTWe aimed to examine the effects of night work on salivary melatonin concentration during and subsequent to night work and the mediating role of light. We included 254 day workers and 87 night workers who were followed during 322 work days and 301 days off work. Each day was defined as the 24 hour period starting from the beginning of a night shift or from waking in the mornings with day work and days off. Light levels were recorded and synchronized with diary information (start and end of sleep and work). On average, participants provided four saliva samples per day, and these were analyzed for melatonin concentration by liquid chromatography tandem mass spectrometry (LC-MS/MS). Differences between day and night workers on work days and days off were assessed with multilevel regression models with melatonin concentration as the primary outcome. All models were stratified or adjusted by time of day. For light exposure, we estimated the total, direct and indirect effects of night work on melatonin concentrations obtaining 95% confidence intervals through bootstrapping. On work days, night workers showed 15% lower salivary melatonin concentrations compared with day workers (−15.0%; 95% CI: −31.4%; 5.2%). During the night, light exposure mediated a melatonin suppression of approximately 6% (−5.9%, 95% CI: −10.2%; −1.5%). No mediating effect of light was seen during the day time. On days off, we observed no difference in melatonin concentrations between day and night workers. These findings are in accordance with a transient and partly light-mediated effect of night work on melatonin production.

We studied the performance and adaptability of 40 nurses (median age 35 years), 20 on permanent day shift and 20 on permanent night shift with fast rotation of work and days off, matched for age, gender, and socio-familial responsibilities. For 15 days prior to the study, subjects maintained sleep logs and trained for performance tests. Questionnaires were administered to evaluate adaptability to shift work. During the experimental phase, sleep/wake patterns were monitored using sleep logs and activity/inactivity with wrist actigraphy. Performance levels were measured with the four choice reaction time and memory test for seven letters, eight times/day during the wake period, days on and off. On the last day of work and first day off, 6-sulfatoxy-melatonin levels were assayed from urine samples collected every 2 hours. Estimated total sleep time during the 15-day experimental period was not significantly different in the dayshift and nightshift nurses. Night nurses shifted regularly to daytime activities on days off and, as a group, were significantly sleep deprived on work days with napping on the job in 9 of the 20 night shift nurses (mean of 114+/-45 minutes per shift) and a significant performance decrement during the work period. Further analysis revealed two subgroups of night nurses: The majority (14 nurses) had a mean peak of 6-sulfatoxy-melatonin at 0718 hours on days off and no peak during night work while the other 6 night shift nurses presented a fast melatonin shift with two clear peaks on both work and days off. Comparison of performance scores revealed that all nurses performed similarly on days off. Daytime nurses and fast-shifting night nurses had similar scores on work days, while nonshifting night nurses had significantly lower scores at work. Despite similar gender, age, social conditions, and light exposure levels, a minority of the nurses studied possessed the physiological ability to adapt to a fast-shifting sleep-wake schedule of more than 8 hours and were able to perform appropriately in both conditions. This shift was associated with a change in the acrophase of 6-sulfatoxy-melatonin.

Objectives:We investigated the association of working hours with occupational injuries in hospital shift work.Methods:Registry data of occupational injuries of hospital employees from 11 towns and 6 hospital districts were linked to daily payroll data to obtain working hours for 37 days preceding the first incidence of the injury (N=18 700). A case-crossover design and associated matched-pair interval analysis were used to compare working hour characteristics for three separate hazard windows among the same subjects. Conditional logistic regression was used to calculate odds ratios (OR) with 95% confidence intervals (CI).Results:We found an elevated risk of an occupational injury for workdays with evening shifts (OR 1.09, 95% CI 1.03–1.14) and workdays following night shifts (OR 1.33, 95% CI 1.17–1.52). After excluding commuting injuries, the risk increased during the evening shifts (OR 1.15, 95% CI 1.09–1.23) and the work days following night shifts (OR 1.44, 95% CI 1.24–1.69), but was no more significant during the morning shifts. Injury risk increased following a week of ≥5 morning shifts or ≥3 evening shifts, but did not increase according to the number of preceding night shifts or quick returns. The length of the work shift (OR 1.22, CI 1.06–1.42) – not the length of the weekly working hours – was associated with an increased risk.Conclusions:The results indicate an increased occupational injury risk during the evening shifts and during work days following night shifts, with the risk increasing according to the number of evening but not night shifts.

Fourteen volunteer nurses who worked on the night shift at a local hospital recorded their times of sleep, mealtimes and any illness or complaints for 12 consecutive days which included at least one spell of night work and rest days. Whilst awake they made regular assessments of their alertness and collected frequent urine samples for analysis of the rate of excretion of a number of constituents. Rectal temperatures were automatically recorded throughout the day and night. Volunteers were divided into those who worked 1–3 successive nights (short term) and those who worked longer ‘blocks’ (long term). There was no difference between the two groups when their subjective assessment of alertness during night work was considered and in both groups there was a similar change in circadian rhythms when rest days and work days were compared. However, there were differences in the amount of day-time sleep that was taken, the temperatures measured, both on and off duty, between 20.00 and 08.00 hours and the number ...

This study investigated the relationship between night work, supervisor support, and depressive symptoms among full-time wage workers, with a focus on gender differences. A nationwide sample of 22,422 full-time wage workers from the Sixth Korean Working Conditions Survey (2020-2021) was analyzed. Experiences of night work were categorized into 5 groups based on the number of night work days per month: 0, 1-5, 6-10, 11-15, and 16-31. Depressive symptoms were evaluated using the 5-item World Health Organization Well-Being Index. Supervisor support was assessed with 5 items. Workers who engaged in 1-5 days (prevalence ratio [PR], 1.23; 95% confidence interval [CI], 1.12 to 1.36) and 6- 10 days (PR, 1.17; 95% CI, 1.06 to 1.30) of night work per month exhibited a higher prevalence of depressive symptoms than those without night work. After stratifying by supervisor support levels, workers with 1-5 days, 6-10 days, and 11-15 days of night work per month were more likely to experience depressive symptoms compared to those without night work in the low supervisor support group. In contrast, no association was found between night work (≥6 days) and depressive symptoms in the high supervisor support group. Furthermore, gender differences were notable: female workers with 6-10 days (PR, 1.45; 95% CI, 1.23 to 1.70), and 11-15 days (PR, 1.43; 95% CI, 1.08 to 1.90) of night work per month exhibited a higher prevalence of depressive symptoms, whereas their male counterparts did not. This pattern of gender difference was also found among those with low supervisor support. Supervisor support may mitigate the adverse effects of night work on depressive symptoms among full-time wage workers, with differences manifested across genders.

Light Exposure during Days with Night, Outdoor, and Indoor Work.