Seasonal patterns in Chinese population: Validating the seasonal pattern assessment questionnaire and exploring associations with psychiatric diagnoses and biological rhythms

Seasonal patterns (SP) exert a notable influence on the course and prognosis of patients with affective disorders, serving as a specifier in diagnosis. However, there is limited exploration of seasonality among psychotic patients, and the distinctions in seasonality among psychiatric patients remain unclear. In this study, we enrolled 198 psychiatric patients with anxiety and depressive disorders (A&D), bipolar disorder (BD), and schizophrenia (SZ), as well as healthy college students. Online questionnaires, including the Seasonal Pattern Assessment Questionnaire (SPAQ) for seasonality, the Morningness and Eveningness Questionnaire-5 (MEQ-5) for chronotypes, and the Pittsburgh Sleep Quality Index (PSQI), were administered. The validity and reliability of the Chinese version of the SPAQ were thoroughly analyzed, revealing a Cronbach's alpha of 0.896 with a two-factor structure. Results indicated that higher seasonality was correlated with poorer sleep quality and a more delayed chronotype (p < 0.05). Significant monthly variations were particularly evident in BD, specifically in mood, appetite, weight, social activities, and sleep dimensions (p < 0.001). In summary, the Chinese version of SPAQ is validated, demonstrating moderate correlations between seasonality, chronotype, and sleep quality. BD patients exhibited the strongest seasonality, while mood disorder patients displayed more delayed chronotypes than SZ.