Development and Validation of the Seoul Sleep Questionnaire in a Tertiary Sleep Clinic Population

Background and Objective Sleep disorders are common and frequently under-recognized in clinical practice. Existing screening instruments are often disorder-specific or require lengthy assessments. This study aimed to develop and validate the Seoul Sleep Questionnaire (SSQ), a brief screening instrument for common sleep disorders.Methods We retrospectively reviewed data from 1,726 adults who underwent polysomnography at a tertiary sleep clinic between November 2018 and February 2020. Participants completed the SSQ and established sleep questionnaires. Item reduction, exploratory factor analysis (EFA), reliability testing, validity analyses, and receiver operating characteristic (ROC) analyses were performed. To address diagnostic imbalance, sensitivity analyses were conducted using a diagnosis-balanced subsample.Results Item reduction yielded a final 7-item questionnaire. EFA supported a three-factor structure representing obstructive sleep apnea (OSA), insomnia, and parasomnia domains, with good model fit (comparative fit index=0.999, Tucker–Lewis index=0.997, root mean square error of approximation=0.013). Internal consistency was acceptable (McDonald’s ω=0.83). SSQ scores showed significant correlations with subjective and polysomnography-derived sleep measures. The OSA subscale was associated with apnea-hypopnea index (r=0.429, p<0.01), while the insomnia subscale correlated with sleep onset latency and wake after sleep onset. ROC analyses demonstrated acceptable diagnostic performance for OSA (area under the curve [AUC]=0.787) and insomnia (AUC=0.741), and high discriminative ability for parasomnia (AUC=0.919). Comparable results were observed in the diagnosis-balanced subsample.Conclusions The SSQ demonstrated acceptable psychometric properties and diagnostic performance as a brief screening questionnaire in an OSA-dominant tertiary sleep clinic population. Further validation in primary care, community-based, and independent external populations is warranted before broader implementation.