key: cord-252839-mg7gxi3f
authors: Zhao, Xiaolin; Lan, Mengxue; Li, Huixiang; Yang, Juan
title: Perceived Stress and Sleep Quality Among the Non-diseased General Public in China During the 2019 Coronavirus Disease: A Moderated Mediation Model
date: 2020-05-21
journal: Sleep Med
DOI: 10.1016/j.sleep.2020.05.021
sha: 
doc_id: 252839
cord_uid: mg7gxi3f

BACKGROUND: The 2019 coronavirus disease (COVID-19) has spread worldwide, and its associated stressors have resulted in decreased sleep quality among front-line workers. However, in China, the general public displayed more psychological problems than the front-line workers during the pandemic. Therefore, we investigated the influence of perceived stress on the sleep quality of the non-diseased general public and developed a moderated mediation model to explain said relationship. METHODS: Questionnaire-based surveys were conducted online from February 18–25, 2020 with 1,630 Chinese participants (aged 18–68 years). RESULTS: Around one-third (36.38%) of participants were poor sleepers during the COVID-19 pandemic. Moreover, higher perceived stress was significantly associated with higher anxiety levels, which, in turn, was associated with lower sleep quality. Self-esteem moderated the indirect effect of perceived stress on sleep quality through its moderation of the effect of perceived stress on anxiety. This indicated that the mediation effect of anxiety was stronger in those with low levels of self-esteem than in those with high levels of self-esteem. CONCLUSIONS: These findings suggest that both the sleep quality and perceived stress levels of the non-diseased general public required attention during the COVID-19 pandemic. Our findings also identify personality characteristics related to better sleep quality, demonstrating the important role of self-esteem in environmental adaptation.

Since December 2019, the outbreak of the novel coronavirus disease (COVID-19) has 2 infected more than 80,000 individuals in China, and it has since been declared a global 3 pandemic [1] . According to the World Health Organization's report, by April 30, 2020, 4

This study was approved by the review board of the Faculty of Psychology of Southwest 12 University (no. IRB20200218). Anonymous questionnaires were conducted via an online 13 survey platform-"SurveyStar"-from February 18-25, 2020 February 12: the government intensifies checks for confirmed cases, adopts a "reception new patients as much as possible" policy.

February 28: the WHO raised the global risk level for an outbreak to "very high".

March 10: all the 14 mobile cabin hospitals in Wuhan were closed.

to test the significance of indirect effects [52] . The 95% CIs did not include zero, indicating a 1 significant effect. from February 4 to March 10, 2020; existing confirmed cases = cumulative confirmed cases -12 cured cases -death cases. The distribution of PSQI scores is presented in Figure 3 . We also calculated the mean scores 2 of the seven subscales: subjective sleep quality (mean = 0.94, SD = 0.76), sleep latency 3 (mean = 1.24, SD = 0.96), sleep duration (mean = 0.13, SD = 0.44), habitual sleep efficiency 4 (mean = 0.53, SD = 0.83), sleep disturbances (mean = 0.99, SD = 0.53), use of sleep 5 medication (mean = 0.04, SD = 0.31), and daytime dysfunction (mean = 1.02, SD = 0.96). 6

Among the 1,630 participants, there were 1,037 (63.62%) good sleepers and 593 (36.38%) 7 poor sleepers. The results of Pearson's correlations are presented in Table 1 . As expected, higher perceived 13 stress was correlated with lower sleep quality. Higher anxiety was related to higher perceived 14 stress and lower sleep quality. Moreover, higher self-esteem was associated with lower 15 anxiety and better sleep quality. 1 Perceived Stress Scale; SAS = Self-Rating Anxiety Scale; RSE = Rosenberg Self-Esteem 3 Scale; *** P < .001. 4

Controlling for age, education, working or not (ie, whether they left the house to work), and 6 attention to COVID-19, the mediation effect of anxiety was examined. Results showed that a 7 higher level of perceived stress significantly predicted lower sleep quality (see Model 1 of 8 Table 2 ). Higher perceived stress was also a predictor of higher anxiety (see Model 2 of Table  9 2). When controlling for perceived stress, higher anxiety significantly predicted lower sleep 10 quality (see Model 3 of Table 2 ). Moreover, bootstrapping indicated that the mediation effect 11 of anxiety was significant (ab = 0.13, Boot SE = 0.01, Boot 95% CI = [0.11, 0.15]), and it 12 accounted for 66.29% of the total effect. Taken together, anxiety mediated the relationship 13 between perceived stress and sleep quality. 14 = Self-Rating Anxiety Scale; *** P < .001; ** P < .01. 2

Controlling for age, education, working or not, and attention to COVID-19, we conducted the 4 moderated mediation analysis. As Table 3 shows, the interaction (Model 1) between 5 perceived stress and self-esteem significantly predicted anxiety, suggesting that self-esteem 6 moderated the effect of perceived stress on anxiety. Simple slope tests suggested that, for 7 individuals with high (Mean + SD; B simple = 0.59, t = 13.06, p < .001) and low (Mean -SD; 8 B simple = 0.73, t = 16.80, p < .001) self-esteem, higher perceived stress predicted higher 9 anxiety ( Figure 4a ). Nevertheless, the slope for individuals with low self-esteem was larger 10 than that for individuals with high self-esteem. Further, self-esteem significantly moderated 1 the effect of perceived stress on sleep through anxiety. There was a significant indirect effect 2 at each level of self-esteem (Table 4) ; however, the indirect effect of perceived stress on sleep 3 quality through anxiety was stronger at low levels of self-esteem. 4 Table 3 also shows the interaction (Model 2) between perceived stress and self-esteem, 5 which significantly predicted sleep quality. This suggests that self-esteem moderated the 6 direct effect of perceived stress on sleep quality. Simple slope tests ( Figure 4b) showed that, 7 for individuals with low self-esteem, higher perceived stress predicted lower sleep quality 8 (B simple = 0.76, t = 4.53, p < .001); however, for individuals with high self-esteem, perceived 9 stress was not related to sleep quality (B simple = 0.03, t = 1.56, p = .12). 10 Note. N = 1,630. PSQI = Pittsburgh Sleep Quality Index; PSS = Perceived Stress Scale; SAS 1 = Self-Rating Anxiety Scale; RSE = Rosenberg Self-Esteem Scale; *** P < .001; ** P < .01. 2 anxiety was stronger at low levels of self-esteem than at high levels of self-esteem. The direct 13 effect of perceived stress on sleep quality was moderated by self-esteem. 14 The number of poor sleepers in the current study was much higher than the proportion 15 reported in previous Chinese studies, which were not related to better than that of the front-line medical staff (mean PSQI = 8.58; [2]). We cautiously 10 speculate that the countermeasures for COVID-19 may reduce the impact of the pandemic on 11 the sleep quality of the general public. On one hand, to cut-off the transmission of the virus, 12 the general public was encouraged to practice home-isolation and wear masks, which 13 effectively reduced the risk of infection. On the other hand, during the period of 14 home-isolation, the state has implemented many measures to ensure that the daily lives of the 15 general public are as normal as possible; for example, college students can take classes online 16 at home. 17

We found that higher levels of perceived stress predicted lower sleep quality, which is 18 consistent with previous studies [8] [9] [10] [11] [12] [13] . Moreover, perceived stress affected sleep quality 19 through anxiety, indicating that perceived stress increased feelings of anxiety, which, in turn, 20 decreased sleep quality. These results were consistent with Stress and Coping Theory, which 21 proposes that stress occurs when individuals perceive that the demands of environmental 1 stimuli exceed or tax their resources, which results in a changed emotional state (eg, anxiety) 2 that, in turn, affects one's health [56-59,18]. Since perceived stress was measured by the 3 degree of unpredictability, uncontrollability, and overload [42] . in the current study, 4 participants with higher stress perceived lower control over their lives. Accumulating 5 evidence has demonstrated that lower perceived control is associated with higher anxiety 6 levels and more anxiety symptoms [60-64]; therefore, our results were consistent with these 7 models of anxiety, which suggests that control over life plays an important role in anxiety 8 development [65] . In addition, we found that higher anxiety levels predicted worse sleep 9

quality. In line with this study, previous studies have consistently found that higher anxiety 10 levels were associated with worse self-reported health, decreased well-being, higher levels of 11 depression, increased disability, and cognitive impairment [66-72]. 12

Our results showed that self-esteem moderated the relationship between perceived stress 13 and anxiety, which, in turn, moderated the indirect effect of perceived stress on sleep quality 14 through anxiety. Specifically, the effect of perceived stress on anxiety was stronger in those 15 with low self-esteem vs. high self-esteem. These findings are consistent with TMT theory, 16 which suggests that high self-esteem helps buffer against anxiety [35, 36] . Accordingly, faced 17 with the stressors induced by COVID-19, participants with low self-esteem were more likely 18 to experience anxiety than were participants with high self-esteem. Individuals with high 19 self-esteem typically hold more positive beliefs (eg, intelligent, popular, attractive, etc.) about 20 themselves relative to those with low self-esteem [73] [74] [75] . Similarly, compared with 21 individuals with low self-esteem, those with high self-esteem are more confident in their 1 ability and more optimistic about their performance on future tasks, even following a failure 2

[76]. Further, participants with high self-esteem display more self-protection and attribute 3 failure more to external factors than participants with low self-esteem [74,77]. These 4 characteristics of high self-esteem may help reduce anxieties related to threats. In addition, 5

we also found that self-esteem moderated the relationship between perceived stress and sleep 6 quality, indicating that higher perceived stress predicted lower sleep quality in those with low 7 self-esteem, but not in those with high self-esteem. These findings are consistent with 8 previous studies, suggesting that self-esteem is a protective factor for sleep [39, 41] . The roles of personal, relational, and collective self-esteem. PLoS One, 12 (8) 54. Ning, C., Lin, H., Chen, X., Qiao, X., Xu, X., Xu, X., Shen, W., Liu, X., He, N., & 42

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Conceptualization, Methodology, Formal analysis, Investigation, Writing-Original draft preparation, Writing -Review & Editing. Mengxue Lan: Conceptualization, Investigation, Formal analysis. Huixiang Li: Investigation, Formal analysis. Juan Yang: Conceptualization, Writing -Review & Editing, Supervision, Funding acquisition