Sleep quality represents a complex clinical construct that is difficult to define and measure objectively. The Pittsburgh Sleep Quality Index (PSQI) is a self-rated qestionnaire which assesses sleep quality and sleep disturbances over 1-month time interval. In this study clinical and clinimetric properties of the PSQI were assessed over a 12-month period with healthy subjects (n= 30), depressive patients (n= 33), and sleep disorder patients (n= 51) in a Turkish sample. The clinimetric and clinical properties of the PSQI suggest its utility both in clinical practice and psychiatric researches.
