Winter Births and Seasonal Affective Disorder

To the Editor.—  In their article entitled "Seasonal Affective Disorder: A Description of the Syndrome and Preliminary Findings With Light Therapy,"¹ Rosenthal et al noted a (relative) maximum number of late spring and summer birth dates among their patients' children. As expected, this was approximately nine months after the patients' depression-free interval in June through August. If some of the patients' parents had seasonal affective disorder (SAD) (17% of the firstdegree relatives reportedly did), an increase in the number of spring birth dates among the patients might likewise be expected.My hypothesis, however, is that an excess of winter birth dates will be found among such patients. In a recent review of 31 season-of-birth studies of psychiatric patients, I concluded that there was a highly significant excess of winter births among patients with affective disorder (W.U., unpublished data). The hypothesized reason was that postnatal light conditions in winter represented