Big Five Personality Traits and Insomnia Severity in Adults: The Conditional Role of Anxiety and Depression

Insomnia is common and associated with both personality traits and psychological distress, yet it remains unclear how stable dispositional characteristics relate to insomnia severity across levels of emotional distress. Guided by hyperarousal and vulnerability–stress perspectives, this cross-sectional study examined Big Five traits, anxiety, depression, and insomnia severity in a community sample of Greek adults (N = 1,349). Participants completed validated measures of personality, psychological distress, and insomnia severity; sex and age were examined as covariates. Women, young adults aged 18–25, and older adults aged 66+ reported higher insomnia symptoms. At the domain level, insomnia severity was positively associated with Neuroticism and negatively associated with Conscientiousness, Extraversion, and Agreeableness, although Extraversion and Agreeableness did not remain independent predictors in multivariate models. Facet-level analyses showed that Neuroticism-related Anxiety and Depression, lower Organization, and lower Energy level uniquely contributed to insomnia severity. Moderation analyses indicated that anxiety, but not depression, attenuated the Neuroticism–insomnia association, which was strongest when anxiety symptoms were low and weaker, though still significant, at higher anxiety levels. Exploratory analyses suggested that this attenuation was unlikely to reflect a simple ceiling or variance-restriction effect. Findings support person-tailored approaches to insomnia assessment and intervention.