Development, reliability, and validity of the quality of life scale for insomnia: a health-related quality of life instrument for insomnia.

Insomnia is a quality of life (QOL) disorder complicated by various mental or physical daytime dysfunctions in addition to nocturnal insomnia symptoms. This study aimed to develop and examine the reliability and validity of a self-administered scale that can sensitively and easily assess QOL disturbances in patients with insomnia. From 122 patients with primary insomnia (mean age 53.8 ± 17.1 years), 11 items correlated with sleep-related clinical indices were extracted and designated the QOL Scale for insomnia (QOL-I). The QOL-I reliability and validity were evaluated. The analysis included 93 patients with chronic insomnia (mean age 54.2 ± 16.0 years) and 228 healthy participants (45.0 ± 15.7 years). The QOL-I showed high reliability (Cronbach α=0.92). Factor analysis showed that the QOL-I has a one-factor structure. Correlation analysis between the QOL-I and other variables indicated criterion-related validity (p<0.001). The QOL-I demonstrated good reliability and validity and is expected to be a valuable tool for clinically assessing the QOL of patients with insomnia.