BACKGROUND: Obstructive sleep apnoea (OSA) is associated with increased cardiometabolic risk. Although a chronotype, a phenotypic marker of circadian rhythm, appears to influence this relationship, the influence of age-related differences has not been fully elucidated. This study aims to evaluate chronotypes and their association with age in identifying comorbidity risk among patients with OSA. METHODS: In this cross-sectional study of 671 adults from three outpatient sleep clinics (median age 56, interquartile range 47-65; 60.2% men) had a medical history assessment, completed standardised questionnaires, and underwent in-lab polysomnography or home sleep testing. An individual's chronotype was assessed using the Morningness - Eveningness Questionnaire (MEQ), whereas comorbidities were determined based on patients' medical history and/or pharmacological treatment. Multivariable analysis was performed to adjust for potential confounders. RESULTS: The morning chronotype is associated with a higher prevalence of arterial hypertension, dyslipidemia, diabetes mellitus, and cardiovascular disease compared with evening chronotype (all p < 0.05), particularly among participants younger than 60 years. In contrast, depression was more frequently observed among individuals with an evening chronotype, with no significant age-related effect. CONCLUSION: In newly diagnosed patients with OSA, the morning chronotype was primarily associated with cardiometabolic comorbidities, especially in young and middle-aged adults, but not in older individuals, suggesting that it may represent a potential adjunctive clinical marker.