Abstract
Introduction Eveningness, the preference for later sleep and wake times, is associated with shorter sleep duration, poorer sleep quality, and suboptimal dietary choices. While both chronotype and sleep disturbances independently influence diet quality, their interrelationship remains poorly understood, particularly in rural populations experiencing health disparities. This study examines whether insomnia severity mediates the relationship between chronotype and diet quality among rural Appalachian adults. Methods We analyzed data from 295 adults (ages 18+) participating in the Researching Equitable Sleep Time in Kentucky Communities (REST-KY) study across twelve economically distressed Eastern Kentucky counties. Participants were recruited via convenience sampling and completed self-administered baseline surveys in REDCap assessing diet quality using the Rapid Eating Assessment for Participants-Shortened (REAP-S), chronotype using the Morningness-Eveningness Questionnaire (MEQ), and insomnia symptoms using the Insomnia Severity Index (ISI). Statistical analyses were conducted using R version 4.2.0. Pearson correlations examined bivariate associations between continuous variables. Mediation analysis tested whether insomnia symptoms mediate the chronotype-diet quality relationship, with bootstrapped 95% confidence intervals (10,000 simulations) estimating indirect, direct, and total effects. All paths were adjusted for sex, age, income, education, and living alone. Results Participants were predominantly female (73.9%), aged 45.7±12.9 years, and living with others (80.3%). Pearson correlations revealed modest positive associations between eveningness and insomnia severity (r=-0.31) and between diet quality and insomnia severity (r=-0.25), and a modest negative association between eveningness and diet quality (r=0.32). The adjusted mediation model demonstrated a significant total effect of chronotype on diet quality (p< 0.001). The indirect effect indicated that later chronotype (eveningness) was associated with poorer diet quality through lower insomnia symptoms (p=0.009). Eveningness was also directly associated with poorer diet quality independent of insomnia (p=0.001). Approximately 17% of the chronotype effect on diet quality was mediated through insomnia severity. Conclusion Among rural Appalachian adults, eveningness is associated with poorer diet quality, with insomnia severity partially mediating this relationship. These findings suggest that interventions targeting sleep timing and insomnia symptoms may improve dietary behaviors in this vulnerable population, offering potential pathways for addressing multiple health disparities simultaneously. Support (if any) R01MD016236