At the beginning of 2020, the outbreak of respiratory diseases caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has emerged around the world, which is highly infectious and pathogenic [1]. On 11 February 2020, WHO named the disease caused by coronavirus 2 as COVID-19 [2]. So far, the infection of COVID-19 is still spreading, and this virus poses a serious threat to public health. The COVID-19 has also caused huge damage in China. As of 7 April 2021, the COVID-19 pandemic in China has resulted in 102,970 infections, of which 4851 have died [3]. Since the COVID-19 outbreak, it has triggered a global recession, while social distance, self-isolation and travel restrictions have reduced the workforce and led to loss of many jobs [4]. At the same time, the pandemic also changed people’s lifestyles which may include eating habits, exercise habits, learning and working style, et al. Due to the impact of the pandemic of COVID-19, psychological pressure of individuals was increased, sleep quality decreased, anxiety, depression, loneliness and a series of mental health problems appeared [5]. A population survey in China showed that during the COVID-19 pandemic, individuals were widely stressed, with 52.1% of 263 participants feeling fear or anxiety about the pandemic [6]. Moreover, Liu and Xie’s survey on the psychological status of the Chinese population showed that 27% of the respondents were depressed, and 33.2% of the respondents suffered from poor sleep quality [7, 8].
Sleep, as one of the most important human behaviors, is highly sensitive in life and susceptible to various factors [9]. The negative impact of the COVID-19 pandemic on economy, education, work and life can increase the psychological stress of individuals, which can further affect the quality of sleep [10]. In a study of 365 COVID-19 patients surveyed, 69.6% reported having at least one sleep disturbance during the COVID-19 pandemic, with frequent awakenings being the most common problem [11]. Similarly, a survey on sleep quality among 1,931 front-line medical workers showed that the prevalence of sleep disorders was 18.4% [12]. However, decreased quality of sleep appeared not only in patients and high-risk occupations, but also in ordinary population. Stanton’s survey of the Australian public showed that 40.7% of respondents said their sleep quality had declined due to the outbreak of COVID-19 [13]. Meanwhile, the general population in China also suffered from poor sleep quality at the beginning of the COVID-19 outbreak. Ji’s research showed that 22.4% of respondents in China reported poor sleep quality during the early stage of COVID-19 pandemic [14]. Nowadays, the domestic pandemic of COVID-19 has been under control with the efforts of Chinese government, but the psychological impacts may still persist [15]. Therefore, during the normalization of COVID-19 pandemic prevention and control, the sleep quality of the Chinese public and its influencing factors are worthy of study.
There was widespread stress among individuals due to the impact of the COVID-19 pandemic. Some scholars divided this stress into five areas, including danger and contamination fears, fears about socio-economic consequences, xenophobia, compulsive checking and reassurance seeking, and traumatic stress symptoms about COVID-19 [16]. First of all, COVID-19 viruses are associated with severe illness or death and are highly infectious, so many people exhibit fears of contacting with possibly contaminated objects or patients [17]. Secondly, the outbreak of COVID-19 also had a serious impact on global economy. For example, people’s incomes would be reduced, unemployment would rise, and transportation or services would be limited, which would increase the stress of individuals [4]. Thirdly, at present, Chinese pandemic prevention and control was relatively stable, but the existence of imported cases and the safety problems of imported food will also cause stress on domestic public [18, 19]. Lastly, many people exhibit compulsive checking and reassurance seeking regarding possible pandemic-related threats or experience traumatic stress symptoms, such as frequent nightmares and intrusive thinking [16, 20–22]. People’s exposure to stress is associated with decreased sleep quality, while people with higher perceived stress tend to have lower sleep quality. A survey of 1,262 Wuhan residents who were experiencing great stress as a result of the COVID-19 pandemic, 30.6% of the residents showed sleep problems [23].
Worries have common characteristics of repetitive cognitive mechanism, namely negative emotions and orientation away from the present [24]. In public health emergencies, individuals generally have worries about the future development of the events, as well as worries about their own study, work and life [25]. From the beginning of 2020 to the present, the COVID-19 pandemic has lasted for more than a year. Affected by the long-lasting COVID-19 pandemic, individuals worry about the uncertainty of future economic income, employment environment, and future life [26]. Previous studies have found that during the COVID-19 pandemic, people’s worries caused a decline in sleep quality and an increase in the frequency of insomnia [27]. Similarly, The study of 584 subjects in Argentina found that the incidence of insomnia during the COVID-19 pandemic was 45%, which has been linked to daytime worries [28].
Resilience is defined as “having not only important psychological skills or abilities, but also the ability of the individuals to use family, social and external support systems to better cope with stress” [29]. Previous research has found that an individual’s resilience is associated with their sleep quality, and low resilience leads to poorer sleep quality [30]. But Some individuals who are stressed and worried don’t tend to suffer from poor sleep quality, and part of the reason was the high resilience. Because they were able to overcome difficulties in adversity and adapt to a new situation with a positive attitude and manner, even if the beginning of an event is negative [31]. During the COVID-19 pandemic, the impact of resilience on sleep quality is particularly obvious. There were some front-line medical staff who had better sleep quality because they were determined to overcome COVID-19, had firm willpower, and were well-adapted to the current bad life [32]. On the contrary, during the COVID-19 pandemic, there were still some ordinary people with poor resilience and their sleep quality was affected. Ephraim believed that when facing the COVID-19 pandemic, people with lower resilience lacked the ability to seek help and social support, and were more likely to feel lonely and helpless, which further affected their sleep quality [27].
The purpose of this study was to investigate the sleep quality of individuals in China during the COVID-19 pandemic through a cross-sectional study. To explore the influencing factors of sleep quality, particularly the effects of stress, worries and resilience experienced during the COVID-19 pandemic on sleep quality. It provided a theoretical basis for the study of sleep quality in the pandemic of COVID-19. Most importantly, during the normalization of COVID-19 pandemic prevention and control, there has been little research on individual’s sleep quality and its influencing factors. Therefore, this study has theoretical and practical significance.