Effects of Clockwise and Counterclockwise Job Shift Work Rotation on Sleep and Work-Life Balance on Hospital Nurses

This cross-sectional study was conducted in two major hospitals in Northern Italy with the voluntary participation of 100 registered female nurses, 50 from each hospital corresponding to approximately 80% of the total eligible workforce. As shown in Figure 1, the group of 50 nurses in Hospital 1 had been working on a continuous, rapid CW rotation schedule with the following sequence: Morning (6 a.m.–2 p.m.), Afternoon (2 p.m.–10 p.m.), Night (10 p.m.–6 a.m.) followed by 2 rest days (48 h). The other group of 50 nurses, in Hospital 2, had been working on a continuous, rapid CCW rotation schedule with the following sequence. Afternoon (2 p.m.–10 p.m.), Morning (6 a.m.–2 p.m.), Morning (6 a.m.–2 p.m.)/Night (10 p.m.–6 a.m.) followed by 3 rest days (80 h). Both groups worked on an 8-h shift system.

In order to minimize heterogeneity between the two groups, all nurses participating in the study were normotensive and normal-weight (body mass index (BMI) 18–23 kg/m²) and they were deemed eligible for shift work by their respective employing hospitals. In addition, the two groups of nurses were homogeneously enrolled from the same following wards of the two hospitals: Internal Medicine (13/50), Nephrology 12/50), Surgery 13/50, and Cardiology (12/50). Thus, it was assumed that nurses’ job tasks were characterized by comparable physical and cognitive requirements. The local organization of nursing staff decided on the CW shift rotation for the nurses working in Hospital 1 and CCW shift rotation for nurses working in Hospital 2.

Ethical approval was granted by the Local Ethics Committees of the target hospitals. All subjects participating in the study provided an informed consent (ethical approval code: SWNURS-633/CE).

An ad hoc questionnaire and a daily diary were specially designed for the study with the purpose to assess several aspects that would help determine the nurses’ psychological and physical well-being. Specifically, the quantity and quality of sleep, work performance, and attitude, their level of satisfaction with their social/family life and lifestyle habits were evaluated.

A self-administered questionnaire in a closed question format was answered anonymously by each nurse at the onset of the study. The questionnaire was used to obtain general information about number of years in shift work, whether they had children, sleep quantity and quality, work performance, perception of well-being, lifestyle habits, and overall satisfaction with family and social relationships.

Sleep quantity was calculated as the mean hours during the entire shift cycle. Sleep duration after the night shift was determined by asking about the hours (h) slept on average. (Responses grouped as <6 h, 6–9 h, >9 h).

Sleep quality was evaluated by inquiring about sleep disturbances and by how rested the participant felt. The following questions were asked: ‘Do you have frequent awakening episodes during sleep?’: ‘Do you have difficulty falling asleep?’: ‘Do you feel rested at the start of the shift?’ (yes/no response).

Effects on lifestyle, family, and social life were assessed from questions such as: ‘Do you feel that work interferes with your family life?’: ‘Do you feel that work interferes with your social life?’: ‘Do you find it difficult to manage domestic responsibilities?’ (yes/no response).

Effects on alertness and performance during shifts were evaluated through questions such as: ‘Do you have frequent episodes of inattention at work?’: ‘Do you find it difficult at times to keep up with the work load?’ (yes/no response): ‘During which shift do you have more problems concentrating?’ (morning/afternoon/night response).

In addition, the nurses had to fill out a daily diary at a prefixed time (between 12 noon–3 p.m.) on each work day and on rest days, during one rotation cycle which was 6 days long. Therefore, a total of six daily diaries have been filled out by each nurse during the experimental protocol. The diary, which was kept anonymous, contained questions about the participant’s principle activities in the preceding 24 h. Specifically, they were requested to report the number of hours they had slept in the preceding 24 h and to report the number of hours they slept before and after a night shift, when appropriate. Information about sleep quality was obtained by reporting whether they felt rested at the start of the shift (yes/no). In addition, they were asked about the number of coffee cups consumed in the preceding 24 h and, when relevant, during the night shift.

Each participant returned the completed questionnaire and diaries in a sealed envelope. Once collected, the data was registered and statistically analyzed with the aim of specifically investigating the effect of the direction of rapid shift rotation.

Statistical analyses were performed on SPSS 20.0 (SPSS, Inc., Chicago, IL, USA) and GraphPad Prism 7.0 (GraphPad Software, San Diego, CA, USA). Data normality was verified by Kolmogorov–Smirnov test. The data obtained from the questionnaire and diary were analyzed using the Chi-square test for categorical variable. A t-student test was applied for between group comparison regarding continuous variables. In order to check whether “age”, “having children”, and “work experience” were associated with the main outcomes in the present study, Phi (for two dichotomous variables) and point-biserial (for one dichotomic and one continuous variable) coefficients were performed. Significance level was set at 5%.

This study shows that nurses working a CCW rotating schedule sleep significantly less hours per day than those working a CW rotation schedule and, also experience significantly more fragmented sleep. This is in line with previous studies [31,37,38]. Indeed, the retrospective study conducted by Shon and colleagues [31] on a group of blue-collar workers to investigate the effects of direction of rotation on sleep quality showed that the CCW schedule was associated with poorer sleep quality. However, the speed of rotation and the intervals of shift rotation were not identified in the study [31]. Similar findings were reported in a survey study by Barton et al. [39] on 261 workers from five different industries. They had found that a CCW system was associated with more sleep disturbances, particularly when the CCW rotation schedule included ‘quick returns’ (8-h break in between shifts). This was also the type of shift schedule the CCW group in the present study worked with, and with similar results. Indeed, in CCW system the break between the afternoon and morning shift and between morning and night shift lasted 8 h (Figure 1). The findings of the present study regarding the nurses’ sleep duration before the night shift are in keeping with those reported by Cruz et al. [36] in their study on air traffic control specialists. That study also showed that workers on a rapid CW rotation schedule slept more before the night shift [36].

The greater reduction in the quantity and quality of sleep experienced by the nurses on the CCW rotation schedule could be due to the differences in the intervals between consecutive shift blocks which result from the differing direction of rotation in the two systems. This interpretation would reinforce the suggestion by Barton et al. [39] that the problem may not be due to the direction of shift rotation alone but rather to a combination of rotation direction and lengths of breaks between one shift and the next one [39].

In the present study the CW rotation schedule offered longer break intervals (24 h) between consecutive shifts and had a 48-h break interval at the end of the 3-shift blocks. This working schedule is in accordance with the Directive from European Community (Directive 2003/88/EC—working time). In contrast, the CCW rotation schedule had an 8-h break between the afternoon and morning shift, a 16-h break between the morning and the following morning shift and an 8-h break between the morning and night shift and a longer rest period of 80 h at the end of the shift cycle. However, although nurses working on a CCW schedule had a longer rest period at the end of the shift cycle (three days off), which should allow sleep recovery, the ‘quick returns’ from one shift to the next one during work days seem to restrict sleep duration and recovery resulting in fatigue accumulation. In addition, sleep time may be further restricted during those short breaks if there are children to care for at home. Furthermore, the longer break intervals between shifts on the CW rotation schedule may allow for more adequate rest and sleep recovery than the CCW schedule.

The present study found that, following the night shift, both groups slept the least number of hours even though they were on a rest day. This is likely due to an attempt to sleep during the day when stress hormone levels such as corticosteroids and catecholamines are at the highest levels [23] under the influence of the light–dark cycle and other environmental cues which promote wakefulness [40]. In accordance with this observation, a previous study by Furlan et al. [13] on steel industry shift workers rotating on a CCW direction found that daytime sleep following the night shift was significantly less (5 h) than the hours of sleep following the morning and afternoon shifts (6 and 8 h, respectively). The authors concluded that this observation could be due to a mismatch between circadian rhythms of stress-related biological variables and the work–sleep schedule.

Previous studies showed that shortened and fragmented sleep can lead to fatigue and decreased cognitive performances [11,41,42]. This might explain why more nurses working a CCW rotation reported feeling less rested at shift onset and had more difficulty maintaining attention levels at work. A significantly higher percentage of nurses from the CCW group reported the most difficulty concentrating during the night shift. This is probably due to having had a break interval of only 8 h after having worked the morning shift. In contrast, nurses on a CW schedule, who had a longer break from the previous shift and slept about 10 h before the night shift, seemed to perform better at work. The CCW nurses of this study, in addition to being out of sync with the day–night cycle, were required to work a CCW schedule which included quick returns. The combination of these factors might further exacerbate cognitive impairment during night shifts [16,43]. Furthermore, the increased coffee consumption during the night shift by CCW rotating nurses suggests its use as a countermeasure to sleepiness.

Sleep loss has been shown to decrease cognitive capabilities such as concentration, attention span, and reaction time which, in turn, increase the risk of work related errors and accidents [40,44]. This is of great importance since nurses must maintain maximum levels of vigilance and attention during work to ensure efficient patient care and safety. In addition, it is well-known that sleep deprivation is associated with alteration of cardiovascular autonomic control characterized by a chronic sympathetic overactivity that may promote cardiovascular diseases [45].

The present study indicates that a rapid CCW direction rotation schedule is associated with increased work–family/social conflict. Nurses, working on CCW rotation schedules, were significantly less satisfied with their social and family life. This is in keeping with previous studies [38,39]. A longitudinal prospective study performed by Van Amelsvoort et al. [38] which included 776 three-shift workers (mostly males) concluded that working on a CW rotation led to less work–family conflict than on a CCW rotation. Similarly, a study by Barton et al. [39] reported that workers on a CCW schedule experienced more social and domestic disruption than workers on a CW schedule. Shift work, in general, obliges the worker to work irregular hours leaving a period of free time which is out of sync with the free time of most other people [46]. In addition, if the quick returns associated with the CCW rotation schedule make it harder to sleep sufficiently and have time for family and friends, this working organization may lead to lower work and life satisfaction. Therefore, it seems that a CW rotation schedule allows a healthier balance between work and private life, ultimately leading to a better quality of family and social life.

Data on the effect of direction of rotation on female subjects is still limited since most of the literature includes studies performed on predominantly male populations. Given that men and women may have different roles in their domestic life, the effects of the direction of rotation could potentially yield different results in different populations. This study, therefore, adds to the limited existing data on the influence of the direction of rotation on sleep measures, work performance, and social and domestic life on an entirely female population. The sample size of this study might represent a potential limitation of the study. On the other hand, the homogenous characteristics of the study population enrolled (sex, age, healthy conditions) minimize the potential confounders [47] and thus represent a strength of the study. However, to ensure appropriate generalizations of the study findings further additional ad hoc surveys might be required. Additionally, as the study was performed on Italian nurses it might not reflect how the direction of shift rotation influences domestic life in other countries and cultures. It is important to mention that since the data was obtained from a self-reporting questionnaire it could be subject to response bias. In the aims of minimizing potential confounding factors, the two groups of nurses in the study worked in comparable medical wards with the same mental and physical work requirements and the diary was required to be filled out by all participants at same hours, every day, over the entire week cycle. Finally, the Questionnaire and Daily Diary designed for this study’s purpose have not yet been validated.