Evening chronotype is associated with affective temperaments, emotional dysregulation, and bipolar-spectrum features: An observational study in 1997 adults from a large community sample.

BACKGROUND

Growing evidence supports an association between chronotype and mental health, with evening chronotype (ET) being associated with increased vulnerability to bipolar disorder (BD).

METHODS

We conducted a cross-sectional survey of adults recruited between February and September 2022 from community COVID-19 points of care in Padua, Italy. Participants completed validated self-report measures assessing chronotype (rMEQ), affective temperaments (Brief-TEMPS-M), emotion regulation (DERS), and subthreshold bipolarity (MDQ and HCL-32-R2). Group differences across chronotypes were examined using ANOVA. Associations between chronotype and psychopathological traits were assessed using regression models adjusted for age and sex. Logistic regression was used to identify sociodemographic and lifestyle factors associated with ET.

RESULTS

A total of 1997 participants (mean age = 31.4 ± 12.35 years; 66.3% female) were enrolled. Overall, 22.68% had ET, 22.33% morning chronotype (MT), and 54.98% neither chronotype (NT). Compared with other chronotypes, ET was associated with higher depressive, anxious, irritable, and cyclothymic temperament, greater emotional dysregulation, and increased bipolar-spectrum scores (all p < 0.001). In logistic regressions, obesity, student status, tobacco and drug use, and lack of religious belief increased the odds of ET, whereas older age, parenthood, living with other people, and good/excellent sleep quality decreased the odds. Cross-sectional design and regional sampling may limit generalizability.

CONCLUSIONS

Our findings support an association between ET and greater emotional dysregulation, cyclothymic temperament, and bipolar-spectrum features, suggesting that circadian-related patterns may be linked to mood instability. Chronotype may serve as a marker of bipolar-spectrum traits. Longitudinal studies are warranted to clarify causality and evaluate its integration into existing prediction/assessment tools for BD at-risk.