In a study of the quantitative relationship between ambient light and
depression in winter seasonal affective disorder, 13 outpatients and 13
normal comparison subjects each wore a light monitor for 1 week. The
patients and normal subjects showed similar light exposure profiles; among
the patients, severity of depression was inversely related to photoperiod,
and there was a trend toward a correlation between greater severity of
depression and later time of onset of morning light exposure. These
findings suggest that vulnerability to short photoperiods may be related to
depression in winter seasonal affective disorder.Abstract Teaser