Seasonal variations of mood and behavior among Japanese graduate students

We conducted a cross sectional epidemiological survey in Kyoto, Japan to assess the effect of seasonal changes in mood and behavior in a sample of Japanese graduate students with regard to gender differences, and to estimate the prevalence of seasonal affective disorder (SAD) among them. The final analysis included 192 students (142 males and 50 females, aged 22–30). The participants completed the Japanese version of the self-administered Seasonal Pattern Assessment Questionnaire (SPAQ). In our sample female graduate students were more affected by the seasonal changes than males regarding their Global Seasonality Scores (GSS), mood and behavior changes as assessed by SPAQ. The GSS of the present and previous reports in Japan were similar, but notably lower compared to studies at the same or similar latitudes around the world. The prevalence rates of winter-SAD (SAD), subsyndromal-SAD (Sub-SAD), and summer-SAD (R-SAD) were 1.35%, 0.45%, and 0.9%, respectively. The lower GSS and lower prevalence rates of SAD and sub-SAD compared to most studies in Western and other Oriental countries at similar latitudes using SPAQ may further raise the possibility of an important role for socio-cultural factors in the perception of seasonal changes, and their effect on mood and behavior accordingly. This needs to be further investigated.