Dates of birth and seasonal changes in well-being among 4904 subjects completing the seasonal pattern assessment questionnaire

Our findings differ from studies of patients with more severe mood disorders, including psychiatric out-patients with S.A.D. The lack of association between seasonality and birthdates in our study adds credence to the view that the aetiology of S.A.D. relates to separable factors predisposing to affective disorders and to seasonality.