The PSQI is a widely used, standardized questionnaire assessing sleep quality in the previous month. The 19 questions are grouped in seven component scores, each exploring a different sleep feature; the sum yields a global PSQI score used to define poor sleep quality when >5. On the basis of the sleep duration component of the PSQI score, self-reported short sleep duration was defined as 30 min), reduced sleep efficiency (1), and daytime dysfunction due to sleepiness (daytime dysfunction component score >1).