title: Validation of the Sinhala version of the Pittsburgh Sleep Quality Index.
abstract: BACKGROUND
  Pittsburg Sleep Quality Index (PSQI) is a widely used standardized instrument to assess sleep quality in clinical and research settings. Objective of the study was to translate the PSQI into Sinhala language and validate using a combined qualitative and quantitative approach.
  
  
  METHODS
  Every fifth patient aged 18-60 years who attended the out-patients department of a tertiary care hospital was recruited. PSQI was translated into Sinhala using a combined qualitative and quantitative approach. Internal consistency was measured using Cronbach's alpha. Construct validity was assessed by comparing the scores in patients who were identified as having depressive disorder according to the Centre for Epidemiologic Studies Depression Scale (CES-D) and those without depressive disorder.
  
  
  RESULTS
  Forty-six participants with depression were compared with 159 non depressed controls. Mean PSQI component scores were significantly higher in depressed patients in 5 components. Factor analysis identified a single component explaining 53.53% of the variance. Cronbach's alpha of 0.85 indicated a high internal consistency.
  
  
  CONCLUSIONS
  The Sinhala translation of the PSQI is a valid and reliable tool to assess sleep quality.
authors.affiliation: Department of Psychiatry, Faculty of Medicine, University of Colombo, Sri Lanka.
authors.forename: D
authors.initials: D
authors.lastname: Anandakumar
authors.affiliation: Department of Psychiatry, Faculty of Medicine, University of Colombo, Sri Lanka. madhudayabandara@yahoo.com.
authors.forename: M
authors.initials: M
authors.lastname: Dayabandara
authors.affiliation: University Psychiatry Unit, National Hospital of Sri Lanka, Sri Lanka.
authors.forename: Suhashini S
authors.initials: SS
authors.lastname: Ratnatunga
authors.affiliation: Department of Psychiatry, Faculty of Medicine, University of Colombo, Sri Lanka.
authors.forename: R
authors.initials: R
authors.lastname: Hanwella
authors.affiliation: Department of Psychiatry, Faculty of Medicine, University of Colombo, Sri Lanka.
authors.forename: Varuni A
authors.initials: VA
authors.lastname: de Silva
mesh_terms: D000328:Adult; D003430:Cross-Sectional Studies; D003866:Depressive Disorder / Q000523:psychology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011594:Psychometrics; D015203:Reproducibility of Results; D012890:Sleep; D012893:Sleep Wake Disorders / Q000150:complications / Q000175:diagnosis*; D011795:Surveys and Questionnaires; D014177:Translations