title: [Reliability and factorial analysis of the Spanish version of the Pittsburg Sleep Quality Index among psychiatric patients].
abstract: BACKGROUND
  The Pittsburgh Sleep Quality Index (PSQI) has become a standard instrument to measure sleep quality. However, its factor structure has not been fully explored and the available Spanish versions have revealed the need to make adaptations. Our objective was to assess the factor structure and reliability of the PSQI.
  
  
  METHODS
  Eighty seven psychiatric patients without treatment and 48 control subjects underwent psychiatric structured assessment and completed the PSQI. Internal consistency and factor structure of PSQI was measured and the scale scores were compared between groups and by gender. Association with age was also calculated.
  
  
  RESULTS
  There were no significant differences between psychiatric patients and control subjects on age and gender. Subjects had no problem understanding and answering the questions in the instrument. The PSQI displayed a satisfactory reliability coefficient (0.78) and component-total score correlations were all significant (0.53-0.77). The PSQI showed two main factors: sleep duration and sleep quality. Patients obtained significantly higher scores than controls, in both the global and the component scores, with the exception of sleep duration. The PSQI scores were not significantly different between males and females and were not associated with age.
  
  
  CONCLUSIONS
  The PSQI is a reliable instrument to measure sleep quality in Mexican subjects.
authors.affiliation: Instituto Nacional de Psiquiatría Ramón de la Fuente Muñiz, SSA, Tlalpan, México DF, México. jimalex@imp.edu.mx
authors.forename: Alejandro
authors.initials: A
authors.lastname: Jiménez-Genchi
authors.forename: Eduardo
authors.initials: E
authors.lastname: Monteverde-Maldonado
authors.forename: Alejandro
authors.initials: A
authors.lastname: Nenclares-Portocarrero
authors.forename: Gabriel
authors.initials: G
authors.lastname: Esquivel-Adame
authors.forename: Adriana
authors.initials: A
authors.lastname: de la Vega-Pacheco
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D005163:Factor Analysis, Statistical; D005260:Female; D006801:Humans; D007802:Language; D008297:Male; D001523:Mental Disorders / Q000503:physiopathology*; D008875:Middle Aged; D011788:Quality of Life; D015203:Reproducibility of Results; D012890:Sleep; D011795:Surveys and Questionnaires; D055815:Young Adult