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

Insomnia 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.