Sleep Apnea and Risk of Comorbid Insomnia in Arab, Black, and White Women and Men; A Longitudinal Study.

STUDY OBJECTIVES: Comorbid insomnia and sleep apnea (COMISA) results in worse health outcomes than either condition alone. While the bidirectional link between obstructive sleep apnea (OSA) and insomnia is established, the causal trajectory from OSA to incident insomnia - and potential disparities by sex, race, and ethnicity - remains understudied. We investigated the association between OSA and incident insomnia within a large, diverse clinical cohort. METHODS: We conducted a retrospective cohort study of 313,953 adults (aged 40-85 years) within the Electronic Medical Records (EMR) of the University of Michigan Health System (2012-2023). Participants were required to be insomnia-free for one year following cohort entry. Arab ethnicity was identified using a validated surname-based algorithm, while Black and White designations were based on EMR self-report.To estimate the risk of incident insomnia following an OSA diagnosis, we employed multivariable Cox proportional hazards models adjusted for age, sex, race and ethnicity, BMI, and Area Deprivation Index, a measure of socioeconomic disadvantage. Interaction terms were included to evaluate whether the association between OSA and insomnia differed significantly across sex, racial, and ethnic subgroups. RESULTS: OSA diagnosis was associated with a significantly increased risk of subsequent insomnia. Although these associations did not vary by sex, significant interactions were observed according to race and ethnicity (interaction term p<0.04). Arab (HR=1.57; 95% CI [1.34-1.84]) and Black patients (HR=1.57; 95% CI [1.45-1.70]) exhibited a higher hazard of incident insomnia than White patients (HR=1.39; 95% CI [1.35-1.43]). CONCLUSIONS: These findings demonstrate that Arab and Black patients face a disproportionately higher risk of developing COMISA following OSA diagnosis.