The association between seasonal and premenstrual symptoms is continuous and is not fully accounted for by depressive symptoms.

Seasonal affective disorder (SAD) frequently co-occurs with premenstrual dysphoric disorder. Explanations of this comorbidity highlighting the cyclical nature of female sex hormones imply that seasonal and premenstrual symptoms should correlate positively even in nonclinical samples. In a sample of 91 female college students, we found a sizable positive correlation (r = .45; p < 0.001) between seasonal and premenstrual symptoms. This relation held up even in a subsample selected on the basis of not qualifying for SAD or subsyndromal SAD on a screening measure. Although the correlation was reduced when depressive symptom severity was statistically controlled, it remained positive and significant. Future research testing possible explanations of the co-occurrence of seasonal and premenstrual symptoms should incorporate the full range of severity on symptom variables, treating them as continua rather than solely as binary categories.