Psychometric assessment of subjective sleep quality using the Japanese version of the Pittsburgh Sleep Quality Index (PSQI-J) in psychiatric disordered and control subjects

Subjective sleep quality has been identified as an important clinical const ruct in psychiatric disordered patients. The Pittsburgh Sleep Quality Index (PSQI), one of the most widely used standardized measures to assess subjec tive sleep quality, generates a global score and scores seven components. T he present study psychometrically assessed clinical profiles of subjective sleep quality in 82 control and 92 psychiatric disordered subjects (primary insomnia, n = 14; major depression, n = 30; generalized anxiety disorder, n = 24; and schizophrenia, n = 24), using the Japanese version of the Pitts burgh Sleep Quality Index (PSQI-J). The overall reliability coefficient of the PSQI-J was high (Cronbach's alpha = 0.77). Correlation coefficients bet ween the PSQI-J global and component scores were statistically significant. The PSQI-J global and component mean scores were significantly higher in p sychiatric disordered subjects than control subjects, except for the compon ent of sleep duration. Using a cut-off point of 5.5 in the PSQI-J global sc ore, estimations of sensitivity and specificity provided 85.7 and 86.6% for primary insomnia, 80.0 and 86.6% fur major depression, 83.3 and 86.6% for generalized anxiety disorder, and 83.3 and 86.6% for schizophrenia, respect ively. The present study supports the utility of the PSQI-J as a reliable a nd valid measure fur subjective sleep quality in clinical practice and rese arch. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.