The reliability and validity of the Korean version of the sleep health index using self-report measures and wearable-derived sleep metrics

Purpose: This study aimed to validate the Korean version of the Sleep Health Index (K-SHI) using both self-report measures and objective sleep indices from wearable devices. Methods: A total of 204 adults (mean age 30.35 ± 9.76 years, 64.71% female) were recruited and categorized into insomnia and good sleeper groups. Participants completed the K-SHI, the Insomnia Severity Index (ISI) and the Pittsburgh Sleep Quality Index (PSQI). Objective sleep indices were collected using a wearable device (Fitbit Inspire 3) for 4 weeks. Confirmatory factor analysis (CFA), and analyses for internal consistency, test-retest reliability, and convergent validity, and group comparisons were conducted. Results: CFA supported a three-factor model (x² = 78.51(df = 52, p <.01), CFI = 0.963, TLI = 0.952, RMSEA = 0.050, SRMR = 0.049). The K-SHI showed adequate internal consistency (Cronbach’s α = 0.766) and test-retest reliability (r =.871, p <.001). The K-SHI total score was significantly associated with ISI (r = −.545, p <.001) and PSQI (r = −.564, p <.001). When correlated with the wearable device, the K-SHI sleep duration subindex was significantly associated with mean total sleep time (r =.170, p <.05), mean sleep onset (r = −.147, p <.05), and total sleep time standard deviation (r = −.168, p <.05). Additionally, the K-SHI total score was associated with mean wake time (r =.160, p <.05) and total sleep time standard deviation (r = −.171, p <.05). The K-SHI total score significantly differentiated the insomnia and good sleeper groups, with notable differences in K-SHI sleep duration and sleep quality subindices, but no significant difference in the K-SHI disordered sleep subindex. Conclusions: These results demonstrate the validity and reliability of the K-SHI, incorporating both subjective self-report measures and objective sleep data from wearable devices.