Effects of season and climate on the first manic episode of bipolar affective disorder in Korea

The purpose of this study was to determine if a seasonal pattern existed for the first manic episodes in Korea. The first manic episodes out of 152 bipolar disorder patients were investigated, in subjects who were admitted in two hospitals in Seoul between 1996 and 1999. Correlations between the monthly climate variables and the first monthly manic episodes indicated that the first manic episodes peaked in 25 cases during March. The mean monthly hours of sunshine and sunlight radiation correlated significantly with manic episodes. Separating the patients into two groups, namely, with and without major depressive episode, only the occurrence of manic episodes with major depressive episode was significantly correlated with mean monthly hours of sunshine. Separating the subjects by gender, the monthly first manic episodes was significantly correlated with the intensity of sunlight radiation in female patients only. These findings suggested that increasing the duration and intensity of sunlight could facilitate breakdown into the manic episodes.