title: [Insomnia Severity Index: some indicators about its reliability and validity on an older adults sample].
abstract: BACKGROUND
  The Insomnia Severity Index (ISI) is a short instrument developed to assess insomnia severity from which there is no study in Spain that guarantees its psychometric properties.
  
  
  OBJECTIVE
  To examine the reliability, factorial structure, and convergent and discriminant validity of the Spanish version of the ISI in an older adult sample.
  
  
  METHODS
  A sample of 230 older adults, aging from 56 to 87 years old (71,11 +/- 5,56) filled in the ISI, together with Athens Insomnia Scale-5 (AIS-5) and Mini Mental State Examination (MMSE).
  
  
  RESULTS
  Principal component analysis shows only one factor which explains 68.99% of total variance, with an internal consistency reliability equals 0.91. Regarding its validity, ISI shows statistically significant positive correlations with AIS-5 (r = 0.93) and negative with MMSE (r = -0.15). Moreover, it differentiates between men and women, people with and without cognitive impairment, and people with and without medical treatment.
  
  
  CONCLUSIONS
  First data of the Spanish version of the ISI endorse single-dimensional structure, with an appropriate internal consistency reliability, and evidences of its measures validity.
authors.affiliation: Universidad de Granada, Facultad de Psicología, Granada, España. jcsierra@ugr.es
authors.forename: J C
authors.initials: JC
authors.lastname: Sierra
authors.forename: V
authors.initials: V
authors.lastname: Guillén-Serrano
authors.forename: P
authors.initials: P
authors.lastname: Santos-Iglesias
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D007802:Language; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D025341:Principal Component Analysis; D011594:Psychometrics; D015203:Reproducibility of Results; D012720:Severity of Illness Index; D012737:Sex Factors; D007319:Sleep Initiation and Maintenance Disorders / Q000453:epidemiology / Q000503:physiopathology; D013030:Spain / Q000453:epidemiology; D011795:Surveys and Questionnaires