Sleep Disturbance Is Prevalent in Older Adults, with More than 30% of Elderly Reporting Im- Paired Sleep Quality and Chronic Difficulties

SLEEP DISTURBANCE IS PREVALENT IN OLDER ADULTS, WITH MORE THAN 30% OF ELDERLY REPORTING IMPAIRED SLEEP QUALITY AND CHRONIC DIFFICULTIES with sleep performance, ranging from long latency periods before falling asleep and frequent awakenings at night to difficulties returning to sleep upon awakening.1 Such disturbances of sleep impact daytime functioning, reduce quality of life, and are reported to lead to declines in heath status2 and increases in all-cause mortality.3 The Pittsburgh Sleep Quality Index (PSQI) is a widely used 19-item self-report questionnaire that measures sleep disturbances.4-7 Seven clinically derived domains of sleep difficulties, including sleep quality, sleep latency, sleep duration, habitual sleep efficiency, sleep disturbances, use of sleeping medications, and daytime dysfunction are assessed by the PSQI. Together, these sleep domains are scored as a single factor or PSQI Sleep Quality. Whereas many psychometric aspects of the PSQI have been examined and found to be appropriate, including internal consistency,4,6 concurrent validity,5,6 and discriminative validity,5,6 the scoring validity of the PSQI has not been statistically examined. Given that efficacy of a scoring system is an essential aspect of validity,8 it is important to know whether a single summed total score, as is presently used in single-factor scoring of the PSQI, best captures the multidimensional nature of sleep disturbance as indexed by the PSQI. In this study, we examined the factor structure of the PSQI score using a cross-validation approach. An exploratory factor analysis (EFA) was followed by a confirmatory factor analysis (CFA) to ascertain the replicability of the factor structure in a second independent sample. Furthermore, the CFA compared the structure obtained through EFA with other logical structures for the PSQI, namely, the single-factor model. PSQI scores were measured in a sample of community-dwelling depressed and nondepressed older adults. This population provides an ideal sample in which to conduct initial factorial examination because of the full range of PSQI scores found in older adults, as well as the high prevalence of sleep disturbances in nondepressed as well as depressed elderly persons.1,9,10