The Sleep Condition Indicator (SCI): Psychometric properties of the European Portuguese version

Abstract

SummaryInsomnia is a highly prevalent sleep disorder. It is the most frequent sleep complaint among Higher Education students. The Sleep Condition Indicator is a self‐report tool aimed at assessing insomnia based on the DSM‐5 criteria. The principal goal of this study was to establish preliminary psychometric properties of the European Portuguese version of the Sleep Condition Indicator in a sample of Higher Education students. Data from a diverse pool of Higher Education students (N = 537) were collected online over a month. Most participants were women (75%) and aged approximately 27 years. The Sleep Condition Indicator demonstrated good internal consistency (α = 0.85), with all the items accounting significantly for the scale reliability. The most appropriate factor structure considering the ordinal nature of the items was unidimensional, with all items explaining 64% of the total variance. However, a two‐factor structure (sleep pattern and sleep‐related impact) was also plausible when other statistical estimators were used. The Sleep Condition Indicator correlated significantly with insomnia severity, vulnerability to stress‐related sleep disturbance, and self‐reported daytime sleepiness. The optimal cut‐off point established based on the receiver operating characteristic curve analysis was ≤ 16. A short version comprising only two items was also viable as suggested by the literature. The Sleep Condition Indicator is a reliable and valid tool for screening for insomnia. More studies with other groups are now required, specifically with clinical samples.