Sleep quality in the general population: psychometric properties of the Pittsburgh Sleep Quality Index, derived from a German community sample of 9284 people.

Abstract Background The Pittsburgh Sleep Quality Index (PSQI) is frequently used to assess sleep problems in patients. The aim of this study was to provide reference values for this questionnaire, to test psychometric properties, and to analyze associations with psychological, sociodemographic, and behavioral factors. Methods A German community sample comprising 9284 adult residents (aged 18–80 years) was surveyed using the PSQI and several other questionnaires. Results According to the generally accepted cut-off (PSQI > 5), 36% of the general population slept badly. Females reported significantly more sleep problems than males (mean scores: M = 5.5 vs. M = 4.4, respectively; effect size d …