Document Type
Article
Peer Reviewed
1
Publication Date
2011
Journal/Book/Conference Title
Psychological Assessment
Abstract
This study examined the reliability and validity of an expanded version of the Iowa Sleep Disturbances Inventory (ISDI; Koffel & Watson, 2010) in 2 samples (219 college students and 200 psychiatric patients). The expanded ISDI includes the scales of Sleep Paralysis and Sleep Hallucinations. These scales, along with the Nightmares scale, help define a higher order factor entitled Unusual Sleep Experiences. This factor was distinct from the factors of Insomnia and Lassitude that were reported previously. The expanded ISDI showed strong evidence of convergent and discriminant validity with the corresponding interview ratings on a clinician rating version of the ISDI. Mean convergent correlations were .68 in students and .70 in patients. Convergent correlations were significantly higher than discriminant correlations in 99.8% of the 624 comparisons. This study also reports the associations of higher order sleep factors with questionnaire and interview measures of pathological symptoms (e.g., depression, anxiety, dissociation, and schizotypy). The Lassitude factor was specific to dysphoria, whereas the Unusual Sleep Experiences factor was specific to posttraumatic stress disorder (PTSD) and dissociation. Finally, several ISDI scales showed strong evidence of specificity in relation to pathological symptoms; in particular, there were strong associations between (a) ISDI Fatigue and measures of dysphoria, (b) ISDI Nightmares and measures of PTSD, and (c) ISDI Sleep Hallucinations and measures of dissociation.
Keywords
sleep, major depression, anxiety disorders, dissociation, schizotypy
Published Article/Book Citation
Published in Psychological Assessment, 2011. DOI:10.1037/a0022818.
Rights
Copyright © 2011 American Psychological Association. Used by permission. http://www.apa.org/journals/pas.
This article may not exactly replicate the final version published in the APA journal. It is not the copy of record.
URL
http://ir.uiowa.edu/psychology_pubs/13
Comments
Published in Psychological Assessment, 2011. DOI:10.1037/a0022818. Copyright © 2011 American Psychological Association. Used by permission. http://www.apa.org/journals/pas.
This article may not exactly replicate the final version published in the APA journal. It is not the copy of record.