title: Psychometric properties of a sleep questionnaire for use in individuals with intellectual disabilities.
abstract: We examined the psychometric properties of one part of the Sleep Questionnaire developed by Simonds and Parraga (SQ-SP; 1982), a questionnaire that is frequently used to explore sleep problems and behaviors related to sleep in individuals with intellectual disability (ID). The SQ-SP was completed for 345 individuals with ID (sleep clinic n = 146; control group n = 103; published studies n = 68; psychiatric clinic n = 28). Internal consistency was good (Cronbach's α = .80) and test-retest reliability for the total SQ-SP score was also good (Spearman's rank correlation = .83, p<.01). Convergent validity was adequate (r = .79, p<.001) and concurrent validity was satisfactory (r = .52, p<.001). Exploratory factor analysis suggested a 5-factor structure (Snoring, Daytime sleepiness, Complaints related to sleep, Sleep apnea and Anxiety related to sleep). Internal consistency of the five factors ranged from modest (Cronbach's α = .57) to good (Cronbach's α = .82). Confirmatory factor analysis corroborated the 5-factor structure. The Composite Sleep Index, the total SQ-SP score and the factor scores on Daytime Sleepiness and Complaints related to sleep were able to differentiate the control group from the sleep clinic group. The SQ-SP appears to be a reliable and valid tool in assessing sleep and different types of sleep disturbance in individuals with ID.
authors.affiliation: GROW School for Oncology and Developmental Biology, Maastricht University, Maastricht, The Netherlands. a.maas@pwo.ru.nl
authors.forename: Anneke P H M
authors.initials: AP
authors.lastname: Maas
authors.forename: Robert
authors.initials: R
authors.lastname: Didden
authors.forename: Hubert
authors.initials: H
authors.lastname: Korzilius
authors.forename: Wiebe
authors.initials: W
authors.lastname: Braam
authors.forename: Philippe
authors.initials: P
authors.lastname: Collin
authors.forename: Marcel G
authors.initials: MG
authors.lastname: Smits
authors.forename: Leopold M G
authors.initials: LM
authors.lastname: Curfs
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D008607:Intellectual Disability / Q000150:complications / Q000523:psychology*; D008297:Male; D008875:Middle Aged; D020447:Parasomnias / Q000150:complications / Q000523:psychology; D011594:Psychometrics / Q000379:methods / Q000592:standards*; D015203:Reproducibility of Results; D012890:Sleep; D012891:Sleep Apnea Syndromes / Q000150:complications / Q000523:psychology; D007319:Sleep Initiation and Maintenance Disorders / Q000150:complications / Q000523:psychology; D012893:Sleep Wake Disorders / Q000150:complications / Q000523:psychology*; D011795:Surveys and Questionnaires / Q000592:standards*; D055815:Young Adult