Measurements

The questionnaire included the following sections: general information, sleep quality, symptoms of stress, anxiety, and depression, social support, and coping strategies.

Sociodemographic characteristics included gender, age, marital status, educational level, years of working, staff type (doctor, nurse, technician, pharmacist, administrator, researcher, logistician, other), professional title, working status (working in the non-epidemic area of the hospital, working in the epidemic area of the hospital, assigned to the ICU of Union Hospital in Wuhan, working at home, resting at home, quarantined), disease history, living situation (living alone or not), exposure to confirmed or suspected COVID-19 cases, average monthly income, personal economic impact from the outbreak, recognition of the effectiveness of protection, and concerns about insufficient supplies of protective materials.

Symptoms of insomnia were measured by the Chinese version of the Self-Rating Scale of Sleep (SRSS), a self-reported scale that was tailored for the Chinese population by psychologists. It has been widely used in studies of the Chinese population, with validated psychometric properties and an established normative range, and the Cronbach's alpha was 0.6418 (13). The SRSS includes 10 items, and each item has 5-point Likert responses. The participant selects a number from 1 to 5 depending on how much the statement applied to him/her over the past month. Total scores can therefore range from 10 to 50. A global SRSS score >22 was classified as sleep disturbance. In this study, the Cronbach's alpha coefficient of the SRSS was 0.893.

Symptoms of stress, anxiety, and depression were measured by the Chinese version of the short-form Depression, Anxiety and Stress Scale (DASS-21), which was first proposed by Lovibond and Lovibond (14) and later reduced to 21 items by Antony et al. (15). Studies by domestic scholars have found that the DASS-21 has high reliability and validity. When applied to college students, the Cronbach's alpha coefficients for the three subscales of the DASS-21 were 0.77, 0.79, and 0.76, respectively (16). There are seven items in each of the three subscales, with scores ranging from 0 to 42. A DASS-21 stress subscale score >14 was classified as stress; anxiety subscale score >7 was classified as anxiety; and depression subscale score >9 was classified as depression. In this study, the Cronbach's alpha coefficients for the three subscales of the DASS-21 were 0.887, 0.870, and 0.880, respectively.

Social support was determined by the Social Support Rating Scale (SSRS), which was developed for the Chinese population by Xiao (17). The SSRS was utilized to assess the level of social support over the past year, including subjective support (four items), objective support (three items), and support available (three items). The total score ranges from 12 to 66 and can be classified into low-level support (≤22), medium-level support (23–44), and high-level support (>44). The SSRS has been validated to have favorable reliability and validity, Liu et al. (18) showed that the Cronbach's alpha coefficient of the SSRS was 0.896 and was 0.849, 0.825, and 0.833, respectively, for the three dimensions of the SSRS. In this study, the Cronbach's alpha coefficient of the SSRS was 0.836 and was 0.784, 0.770, and 0.747, respectively, for the three dimensions of the SSRS. Coping strategy was measured by the Simplified Coping Style Questionnaire (CSQ). This scale was compiled by Xie (19) and includes two dimensions: active coping (12 items) and passive coping (8 items). The items were measured using 4-point Likert scales (0 = ever; 3 = very often). The instrument has been commonly used in China and shows good reliability and validity (19). The Cronbach's alpha coefficient of the CSQ was 0.90 and was 0.89 and 0.78, respectively, for the two dimensions of the CSQ. In this study, the Cronbach's alpha coefficient of the CSQ was 0.903 and was 0.921, and 0.809, respectively, for the two dimensions of the CSQ.