Sleep disturbances among Chinese clinical nurses in general hospitals and its influencing factors

Considering data collection quality and availability, six general hospitals were selected by random cluster sampling from among all tertiary referral hospitals (38 tertiary referral hospitals in total) in Shandong Province, China. Among the nurses in the above six hospitals, whole clinical nurses who have worked for at least 1 year were selected and interviewed. Exclusion criteria were as follows: nurses (679 in total) whose sleep was affected by other causes such as drinking tea (at least once a day), drinking liquor (at least once a day), disease (heart failure, hyperthyroidism, heartburn, restless leg syndrome, chronic pain, etc.), family history of sleep disorders and taking medicines. Considering the convenience and economic efficiency during the survey, 367 nurses who took a marriage leave, maternity leave, sick leave, and leave for personal affairs were not included. A total of 5012 clinical nurses completed our questionnaire from May 2015 to December 2015. The study was approved by the Ethics Committee of Shouguang People’s Hospital. All participants in the study were voluntary and provided a written informed consent before participating into this survey. However, 61 questionnaires that lacked the key variables or were filled in irregularly were eliminated. Therefore, 4951 subjects were included.

The self-administered questionnaire comprised of four sections, and it took the subjeccts approximately 20 min to complete.

The Pittsburgh Sleep Quality Index (PSQI) [28] was employed in the present study to estimate the prevalence of sleep disturbances. The PSQI evaluates multiple dimensions of sleep over a 1-month period [29‐31]. Nineteen individual items generate seven component scores: subjective sleep quality, sleep duration, sleep latency, habitual sleep efficiency, sleep disturbances, the use of sleeping medications, and daytime dysfunction [29]. The seven component scores were summed for one global score of subjective sleep quality (range: 0–21), and higher scores represent poorer subjective sleep quality [29]. The Chinese version of the PSQI has good overall reliability (r = 0.82–0.83) and test–retest reliability (r = 0.77–0.85) [28]. A PSQI global score > 5 yielded a sensitivity of 98% and a specificity of 55%, as a marker for poor sleep in primary sleep disturbance sufferers vs. healthy controls [28]. Respondents were classified as having sleep disturbances if they obtained a PSQI global score > 5 [28‐31].

The Chinese version of the 12-item Short Form Health Survey (SF-12) was used to measure QoL. SF-12 is a practical scale for large group comparisons with a focus on overall physical and mental health outcomes [32‐34]. Researches have indicated that the Chinese version of SF-12 is an effective measurement tool for the Chinese population [35]. It is feasible and credible [36]. The present study used two components from the scale in the current analysis: Mental Component Summary (MCS) score and Physical Component Summary (PCS) score. These scores were based on weighting responses to all 12 items, with higher scores indicating better QoL.

Sociodemographic and occupational data were gathered on sex, age, education level, marital status, employment status (permanent vs. temporary), departments, number of night shifts per month, years of service, and professional status (registered, primary, intermediate, and senior/deputy senior).

Occupational stress was assessed by a validated Chinese version questionnaire [37‐39]: Job Content Questionnaire (JCQ). The 22-item JCQ, based on the Job Demand Control Support model [40], consists of three dimensions: psychological demand (five items), job control including skill discretion (six items) and decision-making authority (three items), and workplace social support including coworker social support (four items) and supervisor social support (four items) [38, 41]. For each item, the response was recorded using a four-point Likert scale ranging from 1 (strongly disagree) to 4 (strongly agree). The Chinese version of JCQ is a reliable and valid tool for measuring job stressors of the Chinese occupational groups [38]. In the study, Cronbach’s α coefficient for the psychological demand subscale was 0.75, while those for the job control and workplace social support subscales were 0.87 and 0.86, respectively.

The average age of the 4951 nurses was 28 ± 6 years old, including 284 male subjects (5.74%) and 4667 female subjects (94.26%). The average PSQI score was 7.32 ± 3.24, including 3163 subjects with a PSQI ≥5, accounting for 63.9%.

Table 1 shows that sleep disturbances were statistically related to age, gender, department, years of service, night shift frequency per month, professional status and employment status (P < 0.05). Both marital status and educational background were not statistically related to sleep disturbances in nurses.

Results of the univariate analyses revealed that the mean scores of SF12-PCS, SF12-MCS, and perceived health in the past 3 months between subjects with and without sleep disturbances were statistically different (P < 0.05, Table 2).

In terms of the JCQ, the mean scores of decision-making authority, skill discretion, psychological demand, supervisor social support and coworker social support between subjects with and without sleep disturbances were statistically different (P < 0.05, Table 2).

Table 3 shows that sleep disturbances revealed an independent relevance with gender, department, years of service, professional status, night shift frequency per month, employment status, QoL (mental health), perceived health in the past 3 months, decision-making authority, skill discretion, psychological demand, supervisor social support and coworker social support. In other words, the risk factors for sleep disturbances in nurses were female gender, ICU and Emergency Department, many years of service, high night shift frequency, professional status: primary and intermediate, employment status: temporary, poor QoL: poor mental health, low perceived health, high occupational stress (high psychological demand, low job control and low workplace social support).

To our knowledge, this is the first large-scale survey concerning sleep disturbances and associate risk factors of clinical nurses in Mainland China. Participants were sampled from six randomly selected tertiary-level hospitals of different cities in Shandong Province, which improves the generalizability of the results for clinical nurses working in tertiary hospitals in China. The overall prevalence of sleep disturbances in clinical nurses in general hospitals in Mainland China was 63.9%, which was higher than the general population [1, 2, 7, 42‐45]. Using structured questions, an earlier population-based study (n = 9851) reported that the overall prevalence of insomnia among Hong Kong Chinese was at 11.9%, with females being at higher risk for insomnia than males [44]. Other researchers in Tehran [46] found that 53.1% of health care workers had sleep disturbances measured by PSQI, which was lower than that in our finding. A pilot study in Taiwan using the same standard of PSQI [47] also revealed that nurses were most likely to suffer from sleep disturbances with an OR of 5.51 (95% CI: 2.09-14.51), compared to other hospital staff (physician OR = 1). Therefore, clinical nurses are prone to have sleep disturbances than other health care workers.

In China, clinical nurses in general hospitals receive and treat many patients with critical disease, difficult diseases, and major surgery. As such, for nurses in general hospitals, updating their knowledge hierarchy in time and boosting their clinical practice ability are necessary, which may result in potential pressure on nurses. Therefore, the sleep disturbances of clinical nurses may be the focus of more attention.

In line with existing epidemiological data [44, 48, 49], our findings revealed that female nurses suffered from sleep disturbances more easily than male nurses. This finding may be related to the female physiological and psychological features. In China, female nurses need to work and take care of their family at the same time, such that their life pressure is higher than that of male nurses. Sleep disturbances are frequently symptoms of anxiety and depression, which may be reflected in the sleep quality difference caused by gender difference [48, 50]. Thus, their sleep quality may be affected more easily. Therefore, more attention should be paid to the sleep quality of female nurses.

Meanwhile, nurses with primary and intermediate professional status may suffer from sleep disturbances more easily. The Ministry of Health in China classifies the grade of nurses according to their years of service, working ability and capacity for scientific research, as follows: registered, primary, intermediate, deputy senior, and senior. Primary and intermediate nurses still need to master the specialty proficiently and put in considerable effort for in-depth learning. Meanwhile, primary and intermediate nurses are faced with increasing pressure of further job title evaluation.

Our results replicated existing data that sleep disturbances were associated with impaired QoL [51, 52]. However, in our study, only the mental health component was retained in the final model of regression analyses for sleep disturbances. Poor mental health was associated with sleep disturbances in clinical nurses, which was consistent with previous reports [1, 53‐55]. These findings suggest that the pathway that mediated between sleep disturbances and QoL was more likely to be psychological, rather than physical [56].

In our study, more years of service was significantly associated with a greater prevalence of sleep disturbances, indicating that the job nature of clinical nurses affects the prevalence of sleep disturbances among nursing staff. Other researchers have also revealed that more years of service is a risk factor of sleep disturbances [57]. As service years increases, nurses would shoulder greater work pressure and face a more complicated personal relationship, which could all lead to the attack of sleep disturbances; while the sleep quality of nurses with more than 30 years of service would slightly be better. This may be due to the fact that nurses with more than 30 years of service are going to retire, undertake less job tasks, and do not have to take night shifts.

This research indicates that PSQI scores have significant differences in different departments. The departments that resulted in sleep disturbances among nurses most easily are ICU and the Emergency Department. Nurses in the ICU had the highest risk of sleep disturbances, which may be related to the heavy workload, long-term contact with critical and seriously ill patients, evident occupational exposure, high work intensity and high pressure. For example, considering the particularity of the ICU, family members are not allowed to accompany and attend to patients. Thus, clinical nurses of the ICU bear all basic nursing work. The research of other study [58] also revealed that clinical nurses in the ICU show poor sleep quality, fatigue, drowsiness, anxiety and depression. However, the root causes of these findings are unconfirmed. Nurses in the Emergency Department rank top 2 in terms of the occurrence rate of sleep disturbances. Medical disputes often occur in the Emergency Department in China. Meanwhile, emergency nurses need to care for critically and seriously ill patients for a long time. In the process, their mind is highly stressed, their body is fatigued, and their sleep quality may be affected [59].

Nursing personnel with high night shift frequency per month may suffer from sleep disturbances more easily, which was consistent with the finding of other researchers [42, 60, 61]. Clinical nurses frequently take turns in working night shifts, which disturbs their body clock and results in irregular sleep patterns [62, 63]. With the accelerating development of China’s economy, more and more medical services are needed, especially in general hospitals; and nurses in general hospitals are relatively in shortage, such that the monthly night shift frequency of nurses increases. However, whether the additional workload could affect sleep disturbances in nurses would remain unclear as this study did not study the workload in night shifts. Nursing workload in night shifts may be heavy. Most often, nurses during night shifts work independently and lack group support. As such, nurses are more intense in night shifts than in day shifts. Their mind and body are in the stress state. Thus, their cerebral cortex malfunctions and their biological rhythm are disturbed, which may lead to sleep disturbances in nurses.

Our study also revealed that the sleep quality of temporary nurses was more easily affected than that of permanent nurses. Temporary employees experience more job insecurity than permanent ones [64, 65]. Job insecurity has been identified as an important occupational stress factor [66], which contribute negatively to the psychological and physical health and well-being of employees [67‐69]. Temporary nurses, who were more likely to be actually dismissed from work, were more likely to be stressed and work harder, in order to keep their job. Hence, this may lead to sleep disturbances.

Healthcare professionals, especially nurses, are highly stressed [70‐72]. Job strain, a key component of work stress, is a measure of the balance between the psychological demand of a job and the amount of control or decision-making power it affords [18]. In our study, high psychological demand, low job control, and low workplace social support were associated with the development of sleep disturbances, which was similar to another study [73]. We found that scores for psychological demand and skill discretion correlated positively with sleep disturbances, while scores for decision-making authority correlated negatively with sleep disturbances. Working in the hospital is highly stressful, because workers need to deal with unpredictable medical conditions, have excessive workloads and working hours, are exposed to high levels of stress, and are frequently emotionally exhausted [25]. Meanwhile, nurses still need to continuously learn new knowledge, in order to improve their ability, meet job requirements and ensure promotion.

In the present study, clinical nurses sensed a lack of social support from supervisors and peers. In another study [74], work relationships have been proven to be a direct source of stress. Seeking support from coworkers or supervisors may actually represent a health-protecting behavior that could help diffuse the impact of stressors in the workplace [47]. Therefore, measures such as conflict resolution and peer support groups may be provided in tertiary hospitals in China, in order to decrease occupational stress, reduce the development of sleep disturbances and promote health.

The limitations of this study include the use of cross-sectional data and self-report measures. Although there are theoretically sound reasons to assume that the factors mentioned above could affect the sleep quality of nurses, no solid conclusion regarding causal relationships can be made from the data derived from this cross-sectional study. Whether the findings are applicable to all clinical nurses in Mainland China, this could not be assessed by only including one hospital nurse level in the study. The long-term sick leave nurses who did not participate in our study may be affected by sleep disturbances. The study included only QoL measurement and no specific depression or anxiety or other mental health (such as psychiatric disorders or medications) measures, which limited analyzing the relationship of mental health with sleep disturbances. Another limitation is that our study ignored the quantitative interaction between psychological, QoL, occupational and personal factors. Further research needs to consider the relative relationships of intermediate factors to establish sleep disturbances models for clinical nurses.