Our research found that 34.30%, 27.05% of medical workers suffered from sleep and mental problems, respectively. Sleep problems mainly manifested as sleep disturbance (92.8%), and mental problems mainly manifested as obsessive-compulsive (25.6%). Male, working years >15 years, nurse, more night shifts, supporting Wuhan and a two-factor interaction between working years and working shifts were all risk factors for sleep quality. Interventions for sleep and mental problems among medical workers were needed.
Previous studies indicated that the insomnia rate was 37% in Taiwan and 34.2% in Hong Kong during the SARS pandemic[20,21]. Chenxi Zhang et al. reported the insomnia rate was 36.1% among medical staff in their study during the COVID-19 pandemic[2]. Similarly, the present study found that the PSQI score of medical workers was 9, and the prevalence rate of poor sleep quality was 34.30%, mainly manifested as sleep disturbance (92.8%), which meant that the overall sleep quality of medical workers during the COVID -19 pandemic was poor. The reasons were as follows: on the one hand, the outbreak of the pandemic was sudden, the number of infected people was large, which made the workload of medical staff significantly increase. The overload work made the sleep quality decline. On the other hand, during the pandemic period, lots of clinical medical workers were infected, resulting in intense psychological pressure of clinical workers, easy to produce traumatic stress such as anxiety and fear, leading to neuroendocrine disorders and affecting sleep quality. Of note, Haitham Jahram et al.[11] found that 75% - 76% healthcare workers were poor sleepers, which is higher than ours. The difference may be related to the different populations and different definitions of poor sleep quality. In their study, poor sleep quality was defined as PSQI ≥ 5. In the current study, poor sleep quality was identified as PSQI >10. In a word, medical institutions should improve infectious disease prevention and control system, ensure adequate human resources, strengthen psychological counseling and humanistic care for medical workers, reduce their anxiety and work pressure, improve their sleep quality and mental health status.
The current study demonstrated that male, working years >15 years, nurse, more night shifts, supporting Wuhan were risk factors for poor sleep quality. Similarly, previous studies found that nurses were more susceptible to insomnia[2]. The reasons were as follows: In clinical work, doctors often work in the daytime, while nurses may have to work the whole night with frequent night shifts[22], and more night shifts may lead to insomnia, which was found in our study. Furthermore, more contact with patients with higher-severity illness was demonstrated to result in higher IES scores[23]. Nurses often have more contact with patients than doctors, which resulted in poor sleep quality of nurses[2]. Consistent with our finding, Jianbo Lai et al[6] found medical workers in Wuhan showed more severe symptoms of insomnia compared with those outside Wuhan. These findings suggested more stress among medical workers in Wuhan, the epicenter of the pandemic in China, and their sleep quality might require special attention.
Of note, previous studies reported females were more susceptible to insomnia[11,24]. However, we found the sleep quality of males was worse than that of females. The reasons might be that the percentage of male supporting Wuhan (72%, 23 out of 32) was larger than females (45%, 78 out of 175) in the current study, and the medical workers supporting Wuhan were more likely to suffer from insomnia, which leaded to the sleep quality of males was worse than that of females. This study also found that people with working years > 15 years were more likely to suffer from insomnia, which might be related to the decline of physiological function. Moreover, medical workers with long working years often act as department directors or head nurses, so they need to coordinate and manage the work of the department, and consider more things, leading to the decline of sleep quality. Consistent with the study by Haitham Jahram et al.[11], there was no statistical correlation between front-line medical staff and insomnia after multivariate logistic analysis in the present study, but we found that front-line medical staffs were more prone to insomnia in univariate logistic analysis, suggesting that more attention should also be paid to the sleep problems of front-line medical staff [2].
As sleep and mental problems are complex multifactorial problems, the effect of a single factor may be weak, so we should focus on the interactions of multiple factors. However, due to the influence of "dimension disaster", traditional statistical models are not suitable for exploring potential high-order interactions. Generalized multivariate dimension reduction (GMDR), as a non-parametric testing method, can overcome the influence of dimension and correct the confounding factors, which significantly improves the accuracy of prediction. With this method, a three-factor interaction among red meat intake, pickled vegetable and cured meat intake was reported to increase the risk of colorectal cancer[25]. In this study, we found that there was a two-factor interaction of sleep quality among working years and working shifts, which means more attention should be paid on the subjects with more night shifts and working years longer than 15 years. However, it is different between statistical interaction and biological interaction[18], whether these statistical interactions obtained in the current study have biological effects, and the specific mechanisms are still unclear, which should be explored in future research.
Owing to the sudden outbreak of the pandemic, strong infectivity, and the occurrence of multiple clinical medical staff infection, medical workers are susceptible to psychological burden. A cross-sectional study reported the prevalence of psychological abnormality was 14.5% in medical workers during the COVID-19[17].Similarly, our study also showed the mental abnormality of medical workers, and the prevalence of mental abnormality was 27.05%, mainly manifested as obsessive-compulsive symptom, indicating that the mental status of medical staff during the COVID-19 pandemic was poor. However, no significant factors were found associated with mental symptom by logistic analysis and no interactions were found by GMDR analysis, which should be explored in future research.
Our study assessed the sleep quality, mental health status among medical workers during the COVID-19 pandemic, and explored associated factors and their interactions, which could help provide precise interventions of sleep and mental problems for medical workers. However, there were several limitations. First, the causal association between demographic data and sleep quality or mental health status was not certain because of the cross-sectional design. Second, owing to the severe pandemic situation, no large-scale was carried out, only the subjects in Ningbo were investigated, the sample size was limited. Third, due to the time limitation of the pandemic, we conducted a rapid survey based on the Wenjuanxing program, no long-term survey was carried out, which might have an impact on the data. Therefore, a prospective study with a large sample size is expected to be conducted and more objective data on sleep quality and mental health status should be collected.