Reliability and validity of the pittsburgh sleep quality index and the epworth sleepiness scale in older men

Abstract

Background. The Pittsburgh Sleep Quality Index (PSQI) and the Epworth Sleepiness Scale (ESS) are commonly used to quantify sleep and excessive daytime sleepiness in older adults. These measures, however, have not been comprehensively evaluated for their psychometrics in older men. We determined the internal consistency reliability and construct validity of the PSQI and ESS in a sample of older men. Methods. Participants were 3,059 men (mean age = 76.4 years) in the Osteoporotic Fractures in Men Study (MrOS) who completed the two questionnaires, wrist actigraphy, and a range of additional psychosocial and health measures. Results. Internal consistency was adequate for the PSQI (Cronbach's α = .69) and the ESS (α = .70) total scores. PSQI daytime dysfunction and sleep medications components were weakly associated with the total score, but their removal did not notably improve internal consistency. PSQI and ESS totals were associated with each other and with theoretically related variables (ie, actigraphic variables, depressive symptoms, mobility/instrumental activities of daily living, health-related quality of life) in expected directions. The PSQI differentiated participants reporting no sleep disorder from those reporting particular disorders more reliably than the ESS. Conclusions. In general, we found evidence of the internal consistency reliability and construct validity of the PSQI and ESS in older men. Despite low correlation with the PSQI global score, the PSQI daytime dysfunction and sleep medications components do not appreciably reduce the PSQI total score's reliability or validity in older men. © 2011 The Author.