Linear Regression Analysis of Sleep Quality in People with Insomnia in Wuhan City during the COVID-19 Pandemic

Objective COVID-19 has evolved into a major global public health event. The number of people reporting insomnia is growing exponentially during the pandemic. This study aimed to explore the relationship between aggravated insomnia and COVID-19-induced psychological impact on the public, lifestyle changes, and anxiety about the future. Methods In this cross-sectional study, we used the questionnaires from 400 subjects who were obtained from the Department of Encephalopathy of the Wuhan Hospital of Traditional Chinese Medicine between July 2020 and July 2021. The data collected for the study included demographic characteristics of the participants and psychological scales consisting of the Spiegel Sleep Questionnaire, the Fear of COVID-19 Scale (FCV-19S), the Zung Self-Rating Anxiety Scale (SAS), and the Zung Self-Rating Depression Scale (SDS). The independent sample t-test and one-way ANOVA were used to compare the results. Correlation analysis of variables affecting insomnia was performed using Pearson correlation analysis. The degree of influence of the variables on insomnia was determined using linear regression, and a regression equation was derived. Results A total of 400 insomnia patients participated in the survey. The median age was 45.75 ± 15.04 years. The average score of the Spiegel Sleep Questionnaire was 17.29 ± 6.36, that of SAS was 52.47 ± 10.39, that of SDS was 65.89 ± 8.72, and that of FCV-19S was 16.09 ± 6.81. The scores of FCV-19S, SAS, and SDS were closely related to insomnia, and the influencing degree was in the following order: fear, depression, and anxiety (OR = 1.30, 0.709, and 0.63, respectively). Conclusion Fear of COVID-19 can be one of the primary contributors to worsening insomnia.


Introduction
Te novel coronavirus pneumonia (COVID-19) pandemic poses a grave threat to the physical and psychological health of people, causing panic among the global public [1]. Te COVID-19 epidemic has been efectively contained due to the eforts of the Chinese government and health agencies. Te epidemic prevention and control work in China has changed from emergency to the normalization phase [2][3][4][5]. Previous evidence has revealed that the COVID-19 epidemic will have an ongoing efect on humanity [6]. In the later stages of the epidemic, people have experienced psychological problems such as emotional instability, inattentiveness, and depression and reduced motivation.
Insomnia is a common clinical condition. Its etiology and pathogenesis are complex and may involve two aspects: on the one hand, it is associated with gender, age, genetic factors, income status, marital happiness, education level, and other vulnerability factors. On the other hand, it is associated with the sleep environment, sleep hygiene, psychological factors, and physical diseases [7]. It has been confrmed that medical personnel have higher detection rates of sleep problems, depression, and anxiety symptoms under the normalized COVID-19 epidemic prevention and control, at 40.4%, 25.9%, and 9.2%, respectively [7]. Te impact of the pandemic on individual mental health is likely to persist for years after the pandemic [8]. However, the relationships among insomnia, depression, and anxiety during the pandemic remain unclear.
In this study, insomnia patients who were the residents of Wuhan city, the frst place to report the outbreak of the COVID-19 epidemic, were recruited. We aimed to investigate the infuencing factors such as fear of COVID-19, depression, and anxiety for insomnia among residents under normalized COVID-19 prevention and control. Te data collected from this population may refect the relationship between insomnia and the psychological state more comprehensively and therefore may provide better reference for the development of mental health management strategies and targeted psychological interventions.

Participants.
In this study, we used questionnaires to investigate patients at the Department of Encephalopathy of the Wuhan Hospital of Traditional Chinese Medicine from July 2020 to July 2021. Te inclusion criteria were as follows: (1) aged between 18 and 80 years old, (2) diagnosed with chronic insomnia with a duration of ≥6 months, and (3) able to understand the questionnaire and willing to cooperate. Te diagnosis of insomnia was made in accordance with the Chinese Classifcation of Mental Disorders (CCMD-3-R) [9]. Participants who had severe mental illnesses or cardiovascular, cerebrovascular, or other serious diseases were excluded. Researchers collected and uniformly recorded the data. A total of 439 questionnaires were received. After excluding 39 invalid questionnaires, a total of 400 questionnaires were included in the fnal analysis, with an effective recovery rate of 91.12%. Informed consent forms were obtained from all participants. Te study was approved by the Ethics Committee of the Wuhan Hospital of Traditional Chinese Medicine.

Research Tools.
Questionnaires used in the study were as follows: (1) For general demographic data on respondents, the questionnaire included details about their sociodemographic characteristics, including age, gender, marital status, education level, and occupation. (2) As anxiety, depression, and fear are related to insomnia and may be confounding factors, participants were screened for anxiety and depression with the Zung Self-Rating Anxiety Scale (SAS) and the Zung Self-Rating Depression Scale (SDS), respectively. Te Spiegel Sleep Questionnaire was used to assess the severity of insomnia, and the Fear of COVID-19 Scale (FCV-19S) was used to evaluate the fear of COVID-19.
Te Spiegel Sleep Questionnaire is an internationally accepted sleep scale, which assesses 6 domains: sleep latency, sleep duration, night waking occurrences, sleep depth, nighttime dreams, and a feeling of being awake. Each item is scored according to the following scores: 0, 1, 3, 5, and 7, and the cumulative scores of each domain are the total scores of the questionnaire. Te higher the scores, the more severe the insomnia. Te evaluation is as follows: mild insomnia if the total score is ≥12 points, moderate insomnia if the total score is ≥18 points, and severe insomnia if the total score is ≥24 points. Cronbach's α coefcient of the Spiegel Sleep Questionnaire is 0.868. FCV-19S is a reliable and efective tool for assessing the level of fear of COVID-19 and consists of 7 items such as the level of understanding of the epidemic, the level of concern about the epidemic, and the level of panic about the epidemic. Te response for each item on FCV-19S is rated from 1 (strongly disagree) to 5 (strongly agree) on a Likert scale. Te total score is the sum of scores of all items, ranging from 7 to 35, with higher scores indicating greater fear of COVID-19 [10]. Te scale had good reliability in this study, with Cronbach's α coefcient of 0.92.
Zung SAS is used to assess the severity of an individual's anxiety status [11]. Te scale consists of 20 items, and each item is scored on four levels. In accordance with Chinese standards, a score of less than 50 indicates no anxiety symptoms, a score between 50 and 59 indicates mild anxiety, a score between 60 and 69 indicates moderate anxiety, and a score of over 69 indicates severe anxiety. In this study, Cronbach's α coefcient of SAS was 0.770.
Zung SDS is used to assess the severity of an individual's depression status [12]. Te scale consists of 20 items and is scored on four levels. As per Chinese norms, a total score of <53 indicates no depression, a score between 53 and 62 indicates mild depression, a score between 63 and 72 indicates moderate depression, and a score ≥73 points indicates severe depression. In this study, Cronbach's α coefcient of SDS was 0.794. SPSS 25.0 software was used for statistical analysis. Te demographic variables of the participants were descriptively analyzed, and the participants' ages and scale scores were calculated with a mean ± SD (X ± S). Te independent sample t-test and one-way ANOVA were adopted for comparisons between groups. Correlation analysis of variables afecting insomnia was performed using Pearson correlation analysis. We determined the degree of infuence of certain variables on insomnia using linear regression and derived a regression equation.

Physiological Characteristics of Sleep of People with
Insomnia. In terms of sleep time, the average bedtime was 22.34 ± 6.04. Among the study participants, 130 participants went to bed at 11 p.m. (32.5%), accounting for the largest proportion, while only 2 people went to bed at 1 a.m. (0.5%), making up the least percentage. Te average wake-up time was 6.34 ± 0.94, and the number of times they woke during sleep was 2.19 ± 1.31 (Table 2).
Te average score of the Spiegel Sleep Questionnaire in people with insomnia was 17.29 ± 6.36, that of SAS was 52.47 ± 10.39, that of SDS was 65.89 ± 8.72, and that of FCV-19S was 16.09 ± 6.81 (Table 3).

Test of Demographic Diferences in People with Insomnia.
Te independent sample t-test and one-way ANOVA were used to examine the diferences in demographic factors in people with insomnia, and the results are displayed in Table 4. Age, marital status, and occupation were signifcantly diferent demographic factors.

Correlation Analysis of the Variates.
Pearson correlation analysis showed that the independent variables, namely, scores on FCV-19S (fear of COVID-19), SAS (anxiety), and SDS (depression), were signifcantly correlated with the dependent variable, namely, the Spiegel Sleep Questionnaire scores (insomnia) (P < 0.01). Also, the comparative analysis between the three variables showed a signifcant correlation (P < 0.01) ( Table 5).

Linear Regression Analysis of Impact Factors
(1) Te linear regression model ftted well. Te R 2 value was 0.39, which is more than 0.3, indicating that the results of this study could truly and reliably refect the infuence of FCV-19S, SAS, SDS, age, occupation, and marital status on the degree of insomnia (Spiegel Sleep Questionnaire scores). (2) Tere was no multicollinearity between the three independent variables, with all variance infation factor (VIF) values less than 5. We derived the following regression equation between the variables: insomnia degree � 0.91 + 1.30 * FCV-19S + 0.63 * SAS + 0.70 * SDS − 0.005 * age + 0.16 marital status (Table 6).

Discussion
Insomnia is a common clinical disorder with multiple factors afecting its occurrence, including both environmental and behavioral factors. In this study, we found that the fear of COVID-19 is one of the primary contributors to worsening insomnia.
Major epidemic events may afect the factors infuencing mental health [13]. For instance, the global coronavirus epidemic in 2003 caused mental health complications in 14%-61% of infected people, and 14.8%-76.9% people developed mental health problems after the infection [14]. Similarly, a study of 42 COVID-19 patients in the United Kingdom showed that more than one-third of patients had olfactory defcits and taste disturbances [15]. A higher proportion of insomnia cases were also observed in patients  International Journal of Clinical Practice infected with COVID-19 [16]. Tese results suggest that insomnia is related to psychosomatic and socioenvironmental factors related to COVID-19. Some indicators of immune function respond to insomnia with impaired immune function [17]. Te main cytokines involved in the regulation of sleep-wake rhythm are tumor necrosis factor (TNF), interferon, and interleukin (IL) [18]. Clinical observations of the normal sleep-wake cycle showed that proinfammatory cytokines increase in early sleep and that there is an increase in immune cells and anti-infammatory cytokines during the daytime [19]. Moreover, immune function is signifcantly decreased in patients with generalized anxiety with sleep disorder compared to those with generalized anxiety and no sleep disorder [20]. Te reason for this may be that insomnia, as a chronic stress, has a signifcant impact on the brain function and nervous system of the body, leading to dysfunction of 5-HT, which afects the homeostasis of the body. Tese fndings revealed the involvement of neuroendocrine-immune mechanisms in insomnia.
Cytokine storms in COVID-19 are closely associated with organ dysfunction, which can further lead to olfactory defcits or insomnia [21]. Cazzolla et al. suggested that proinfammatory cytokines, specifcally TNF-α, may contribute to COVID-19-induced olfactory defcits and insomnia [22]. Another proinfammatory cytokine, IL-6, increases in cases with olfactory defcits [23,24]. Te process through which these cytokines produce olfactory defcit or insomnia is incomprehensible. Henkin et al. suggested that this efect may be caused by the peripheral or central action of cytokines due to viral infection [25]. Te above data imply a correlation between insomnia and infammatory cytokines related to COVID-19.
Te risk of anxiety, depression, and insomnia increases with psychosomatic changes [6]. Available evidence suggests that some of the measures taken to curb the epidemic may harm vulnerable populations, especially those with mental or physical health problems and mental illness [26,27]. COVID-19 isolation may increase anxiety and depression in people coping with mental or physical problems due to the lack of access to mental health support and positive activities. Tese results imply the efect of the COVID-19 epidemic on insomnia from a psychosomatic perspective.
Te outbreaks of highly contagious diseases can bring associated psychiatric symptoms that suggest COVID-19 is a stressful life event and a leading cause of physical and  Note. * P < 0.05; * * P < 0.01. Note. * * P < 0.01 (two-tailed), signifcant correlation. mental disorders. For instance, the prevalence of anxiety, depression, and insomnia was much higher during the outbreak and remission phases of the COVID-19 outbreak in Hubei Province, China, in 2020 [7]. Moreover, during the COVID-19 pandemic, the relationship between mental health-related factors in 1,100 German study participants with insomnia showed that the prevalence of insomnia, anxiety, and depression was 19.5%, 4.8%, and 6.6%, respectively [28]. Te mean and median insomnia severity index (ISI) scores, patient health questionnaire-4 (PHQ-4) scores, PHQ-2 scores, and generalized anxiety disorder (GAD-2) scores were lower in the noninsomnia group than those in the insomnia group, while the mean and median scores of "life quality" and "health quality" were higher and statistically signifcant (P < 0.05). Pearson's correlation analysis showed that ISI scores were positively correlated with PHQ-2 scores (P < 0.001), GAD-2 scores (P < 0.001), and PHQ-4 scores (P < 0.001). Tis study confrmed that Germans were afected by insomnia, anxiety, and depression during the COVID-19 pandemic more than ever before. Anxiety and depression symptoms had an efect on each other and were more severe in the insomnia group than those in the noninsomnia group. In a study on COVID-19 and factors such as anxiety, depression, and insomnia in Iran, among the 675 people with insomnia, the average age was 40.28 ± 11.15 years and the prevalence of difculty in initiating sleep (DIS), difculty in maintaining sleep (DMS), and early morning awakening (EMA) was 91.4%, 86.7%, and 77%, respectively [29]. DIS, DMS, and EMA were more common in patients with depression and anxiety. Te Fear of COVID-19 Scale (FCV-19S) scores were higher in patients with more severe DIS, DMS, and EMA types (P < 0.001). FCV-19 was a risk factor for all insomnia patterns (DIS, DMS, and EMA; OR � 1.19, 1.12, and 1.02, respectively). Nevertheless, among demographic factors, it is believed that occupation is also a risk factor for insomnia, especially for those who are self-employed, which is diferent from this study. Te reason could be that health precautions and lockdowns may have had a greater impact on their business.
In this study, we focused on the impacts of fear, anxiety, depression, and other factors on people with insomnia in Wuhan city, China, during the COVID-19 epidemic. Our data revealed that the average score of the Spiegel Sleep Questionnaire in people with insomnia was 17.29 ± 6.36, that of SAS was 52.47 ± 10.39, that of SDS was 65.89 ± 8.72, and that of FCV-19S was 16.09 ± 6.81. Most people reported mild to moderate insomnia. Te relationship between selfreported anxiety, depression, and insomnia with respect to regular COVID-19 prevention and control measures among residents in Wuhan city changed after the addition of the variable of fear of COVID-19. Te factors that were previously thought to afect insomnia, anxiety, and depression were diferent in this study. For example, the risk factors for insomnia were advanced age, female, divorce, unemployment, and higher education. Te linear regression analysis showed that fear of COVID-19 was the biggest infuencing factor of insomnia among these four factors followed by depression, anxiety, and marital status. Also, the younger the age is, the more likely the person was anxious, had insomnia, and was fearful. Te above fndings prove the relationship between fear and anxiety, depression, and insomnia. Fear afects the internal balance between mind and body, which leads to mind-body reactions such as stress, depression, anxiety, insomnia, or various physical problems. Te wider community impact on the mental health of people and vulnerable populations will continue for a long time even after the COVID-19 pandemic ends. Terefore, we believe that the fear of COVID-19 is a risk factor for all types of insomnia. Lack of sleep may in turn lead to aggravation of negative emotions such as stress, anxiety, and worry, which creates a vicious cycle and leaves people with insomnia in a state of fear, anxiety, and depression for a long time.
As for the limitations of this study, frst, it is a crosssectional and self-reported survey. Respondents of diferent cultural levels and ages had diferent understandings of the information being collected, so responses may be biased, which could afect the accuracy of the information. Second, the participants of this study were limited to the people with insomnia in Wuhan city, and the sample size was relatively small. Te survey did not target specifc groups, and this study ofers only a general overview.
In conclusion, our study, for the frst time, reported the infuencing factors for insomnia in residents of Wuhan city, China, where COVID-19 was frst reported. Our results show that fear of COVID-19 is one of the primary contributors to increased insomnia. Tese fndings suggest that psychological interventions should be part of the public health response following a major epidemic and must include various intervention strategies, address diferent intervention groups, and have diverse intervention forms. It is also important to let the public fully understand the rationale behind diferent policies during diferent phases of an epidemic, thus eliminating policy blind spots. Government agencies play a role in dispelling public panic by releasing information in a timely manner about the epidemic through ofcial media; at the same time, at diferent phases of the epidemic, prevention and control policies must be adjusted to develop the economy and reduce economic pressure on the public.

Data Availability
All data generated or analyzed during this study are included in this article. Further enquiries can be directed to the corresponding author.

Ethical Approval
Tis study was conducted with approval from the Ethics Committee of the Hubei University of Chinese Medicine (Approval number. HBZY2019-C43-01). Tis study was conducted in accordance with the Declaration of Helsinki.

Consent
Written informed consent was obtained from all participants.

Conflicts of Interest
Te authors declare that they have no conficts of interest.