BACKGROUND: Obstructive sleep apnea (OSA) and psychiatric disorders often coexist, affecting patient outcomes and treatment responses. This relationship, particularly the risk of psychiatric conditions in OSA patients, merits further investigation considering age and sex differences. METHODS: Utilizing the South Korean National Health Insurance claims database (2010-2019), this nationwide-population-based, retrospective study identified OSA patients and matched them with controls based on age and sex. Psychiatric disorders were defined using ICD-10 codes for depression and anxiety. Multivariable logistic regression models, adjusted for demographics and comorbidities, evaluated the association between OSA and psychiatric disorders, with detailed subgroup analyses by age and sex. RESULTS: Among the 103,785 matched pairs, OSA patients had significantly higher odds of depressive disorders [adjusted OR = 1.62 (95 % CI: 1.60-1.63)] and anxiety disorders [adjusted OR = 1.56 (95 % CI: 1.54-1.58)] compared to controls. Females with OSA were particularly susceptible to these psychiatric conditions. The risk of psychiatric disorders in OSA patients increased with age, peaking for depression between 60 and 79 years and for anxiety between 40 and 59 years, before slightly declining in the oldest cohort. CONCLUSION: OSA is significantly associated with an increased risk of depressive and anxiety disorders, with pronounced vulnerabilities observed among females and specific age groups. These findings underscore the need for age- and sex-specific considerations in managing OSA and its psychiatric comorbidities, emphasizing a more individualized approach to treatment to enhance patient outcomes.