Prevalence of seasonal difficulties in mood and behavior among Japanese civil servants.

OBJECTIVE Most prevalence studies of seasonal changes in mood and behavior have come from Western countries. The authors' goal was to determine the prevalence of seasonal changes in mood and behavior in a randomly selected group of Japanese workers. METHOD They administered a Japanese translation of the Seasonal Pattern Assessment Questionnaire to 1,276 civil servants in Nagoya, Japan. RESULTS The estimated prevalence of winter seasonal affective disorder was 0.86%, the estimated prevalence of winter subsyndromal seasonal affective disorder was 0.86%, the estimated prevalence of summer seasonal affective disorder was 0.94%, and the estimated prevalence of summer subsyndromal seasonal affective disorder was 2.12%. CONCLUSIONS The authors conclude that seasonal changes in mood and behavior occur in Japan, but at a lower frequency and with a different profile than in the United States or Europe.