Chronotype Differences in Lipid Profile and Atherogenic Risk Indices Among Patients with Bipolar Disorder

Objective: Bipolar disorder (BD) is associated with a high cardiometabolic burden, influenced by factors such as lifestyle, medication, and circadian disruption. The study aimed to investigate the association between chronotype and cardiometabolic parameters in patients with BD. Materials and Methods: This cross-sectional study included 69 euthymic patients with BD I or II attending a community mental health center in Türkiye. Sociodemographic and clinical data were obtained alongside anthropometric measures, fasting blood samples, and psychometric assessments. Chronotype was determined using the Morningness–Eveningness Questionnaire, and patients were categorized into eveningness, intermediate, or morningness groups. Metabolic markers included body mass index, fasting glucose, triglycerides, total cholesterol, LDL-c, HDL-c, atherogenic coefficient, and Castelli risk indices. Results: Chronotype distribution was 27.5% (n=19) eveningness, 47.8% (n=33) intermediate, and 24.6% (n=17) morningness. Eveningness was associated with significantly lower total cholesterol and LDL-cholesterol levels, as well as more favorable atherogenic coefficient and Castelli risk indices compared with intermediate and morningness types (all FDR-corrected p<0.05). In ANCOVA models, chronotype remained significantly associated with LDL-cholesterol and all atherogenic indices after adjustment for demographic variables, BMI, smoking, antipsychotic treatment, and valproate use (all p<0.05). Higher MEQ scores (greater morningness) were positively correlated with LDL-cholesterol and atherogenic indices. Conclusion: Eveningness was linked to a healthier lipid profile in euthymic patients with bipolar disorder. This finding differs from most earlier studies and suggests that the effect of chronotype on metabolism may change depending on context. Considering chronotype could help personalize care and prevent metabolic problems in bipolar disorder.