Measurement of sleep quality

A PSQI questionnaire translated into Chinese was used to evaluate sleep quality. It is a standard self-report, including a 19-item questionnaire designed to collect a person’s subjective feelings about sleep habits for more than 1 month (Buysse et al., 1989). Each item is divided into four levels, with scores ranging from 0 to 3. PSQI has been used to diagnose sleep disorders in many clinical applications and has been proved to have good reliability, validity, and sensibility (Tsai et al., 2005; Mollayeva et al., 2016). It estimates several different aspects of sleep, which affect seven aspects of sleep problems, including subjective sleep quality, sleep latency, sleep duration, habitual sleep frequency, sleep disorders, use of sleep drugs, and daytime dysfunction (Buysse et al., 1989). The sum constitutes the global sleep quality score (ranging from 0 to 21), and the higher score mean the worse sleep quality. The global PSQI score is divided by 7 points, which can distinguish poor or good sleep. It has high diagnostic sensitivity and specificity in Chinese population (98.3 and 90.2% respectively) (Li et al., 2021).