The World Health Organization’s (WHO’s) China Country Office was informed of cases of pneumonia of unknown cause detected in Wuhan City, Hubei Province, on December 31, 2019 [1]. On January 23, in response to the growing COVID-19 epidemic, the Chinese government locked down Wuhan City [2]. During the first 14 days of lockdown, confirmed cases in China increased dramatically from 571 on January 23 to 28,060 on February 6 [1]. Due to the enforcement of lockdown, most people were restricted to their homes. This confinement has resulted in a changed lifestyle, disrupted chronobiological rhythms, and impacted on mental health [3, 4]. An online survey demonstrated that 30% of participants among Wuhan residents had a sleep disorder in the incipient pandemic [5]. Similarly, an Italian study reported 42.2% of the sample had sleep disturbances and, among them, 17.4% reported moderate/severe insomnia, where the first European country entered a nationwide lockdown [4]. Sleep is an integral part of proper human function [6]. Poorer sleep quality is associated with increased susceptibility to viral infections, lower cognitive functioning, poorer job performance, and worsened mental health [7]. Understanding the influencing mechanism of sleep during the COVID-19 pandemic may help the residents to maintain good sleep status and provide support for design and implementation of interventions for sleep health in pandemic condition.
When confronted with a such sudden and actual disaster, people realize uncertainty surround every aspect of life [8]. Uncertainty is one of the most major cognitive and psychological stressors [9]. Further, factors relating to stress are one of the most important concomitants of sleep complains in the general population [3, 10]. The concept of uncertainty in illness was defined as “the inability to determine the meaning of illness-related events” [11]. Applicable to COVID-19, uncertainty according to Mishel’s initial definition is a cognitive state that occurs when the decision maker is unable to assign definite values to objects and events and/or is unable to accurately predict outcomes because of a lack of sufficient cues [11]. Since this unexpected COVID-19 pandemic has swept across the world, limited knowledge of COVID-19 for diagnosis or treatment, unpredictability of the natural course of contagious illness, and gross disruption of societal functioning and people’s routines may all represent potential sources of uncertainty. Uncertainty has been identified as the greatest single psychological stressor for patients with a life-threatening illness [12].
Intolerance of uncertainty (IU) relates to the cognitive unacceptability of uncertainty and represents a dispositional characteristic from those people who are more likely to “find ambiguity stressful and upsetting, believe uncertainty is negative and should be avoided, and have difficulty functioning in uncertain situations” [13, 14]. Although uncertainty is pervasive and inherent in people’s daily life, individuals who have high degree of perceived uncertainty or who are high in IU experience might significantly impair their daily functioning [15, 16]. A substantial body of research suggests that individual difference in IU foster stress [15, 16]. Theoretical conceptualizations posit that those high in IU are likely to rely on maladaptive behaviors as a coping mechanism when faced with uncertain and potentially aversive situations [17].
A significant association between IU and sleep disturbances in young adults and more particularly Iranian adults was examined [18]. A large body of evidence on clinical research has demonstrated that generalized anxiety disorder (GAD) patients with greater IU suffer from sleep dysfunctions including longer sleep latency, decreased sleep duration, decreased total sleep efficiency, and increased waking periods during sleep time [19, 20]. Research by our group has also demonstrated strong associations between cancer-related uncertainty and insomnia severity among cancer survivors [21]. There is a plethora of studies on uncertainty for clinical patients with chronic diseases. However, research on uncertainty in a lethal and urgent infectious disease outbreak and its side effect is limited among non-patients. The role of IU in sleep problems has not been studied extensively [14]. Unknown is how IU impacts the public in cognitively processing a COVID-19-related stressor, as well as how their sleeping behaviors are influenced by such serious outbreak-related events.
Based on the previous literature, IU appears to be an important element of cognitive vulnerability affecting sleep quality [20]. The current study seeks to explore the potential mechanism for influencing sleep quality under the early stage of COVID-19 outbreak, and to examine how IU and perceived stress impact the relations between uncertainty about COVID-19 and sleep in a sample of Chinese general residents. The following four hypotheses and research question were evaluated in this study. First, we expected a positive association between perceived uncertainty about COVID-19 and IU and, second, following prior studies, an association between IU and perceived stress [15, 22]. Third, in the line with previous research [23], we predicted a positive association between stress and poor sleep. Finally, we treat as exploratory the possibility that IU and stress would take mediating role between uncertainty about COVID-19 and poor sleep.