Validation and reliability of the Athens Insomnia Scale-8 in Chinese psychiatric inpatients

Background: Existing cross-cultural applications of the Athens Insomnia Scale-8 (AIS-8) have been constrained by sample limitations, most notably the absence of psychiatric inpatients in validation datasets. This gap underscores the need to contextualize the scale's performance within specialized clinical populations. Accordingly, this study aims to systematically assess the validity and reliability of the AIS-8 and characterize its psychometric properties among a sample of Chinese psychiatric inpatients, addressing an unmet critical need in cross-cultural insomnia assessment research. Methods: A total of 519 psychiatric inpatients completed the Chinese version of the AIS-8, along with the Generalized Anxiety Disorder-7 (GAD-7) and Patient Health Questionnaire (PHQ-9). After excluding missing values, 411 participants were included in the final analysis. Results: Exploratory factor analysis (EFA) and confirmatory factor analysis (CFA) revealed a two-factor model structure of "nighttime sleep problems" and "daytime dysfunction" for the AIS-8 in Chinese psychiatric populations. Although the item "daytime sleepiness" showed relatively low factor loadings, model fit deteriorated when this item was removed. Strict measurement invariance was established for gender, whereas age, marital status, and occupation exhibited only weak invariance. The AIS-8 demonstrated a Cronbach's alpha of 0.84, and convergent validity was supported by significant positive correlations with the PHQ-9 and GAD-7. Conclusion: The Athens Insomnia Scale-8 (AIS-8) demonstrated acceptable reliability and validity in a sample of Chinese psychiatric inpatients, providing preliminary support for filling an important gap in its cross-cultural validation among specialized psychiatric populations. Given the study's geographical scope and sample characteristics, which represent inherent limitations, the findings tentatively suggest that the AIS-8 may be used as a reliable instrument for clinical insomnia assessment in Chinese psychiatric settings.