Categorical and dimensional assessment of insomnia in the general population

This paper presents two instruments: a dimensional one, the Sleep Condition Indicator (SCI), aimed to assess sleep quality, and a categorical one, the Sleep Disorders Questionnaire (SDQ), designed to identify those suffering from insomnia disorder. We aimed to gather data on insomnia in the studied population and to determine the psychometric properties of the Romanian translations of these two instruments. Using an online questionnaire, we surveyed five hundred eighty eight adults, students from two main cities in Romania and adults from the general community nationwide. A large number of respondents (38.3-45.5%) reported insomnia symptoms and 15.8% were likely to suffer from insomnia disorder. The mean SCI scores were 6.17±2.21 (in the whole sample), without significant differences among genders or age groups. The ROC (Receiver Operating Characteristic) analysis of the SCI, using SDQ as a diagnostic tool, revealed that a good cut-off score for screening for chronic insomnia would be 5 (sensitivity of 82%, specificity of 79%, and accuracy of 83%). Both instruments seem worthy of recommendation for the use in clinical practice or for research, but validation against clinical interview diagnosis of insomnia is imperative.