Effects of light treatment on core body temperature in seasonal affective disorder.

Abnormalities in circadian rhythms of core body temperature have been reported previously in depressed patients. In this study, we compared the temperature rhythms of 10 depressed seasonal affective disorder (SAD) patients with winter depression with those of 12 normal controls and evaluated the effects of bright light on temperature in SAD. Unlike previous studies of depressed patients, the temperature curves of the patients and normal controls during the off-light condition were nearly identical. We found a significant difference in amplitude between the patients in the untreated and light-treated conditions. Although there was no systematic difference in circadian phase across groups or treatment conditions, we present preliminary evidence that suggests that phase-typed subgroups may be present in the population distinguished by their treatment responses.

Seasonal affective disorder and visual impairment: two case studies.

Winter depressive episodes in patients with seasonal affective disorder are induced by light deficiency and are successfully treated by enhancing environmental light. The authors investigated the role of abnormal visual information processing in the genesis of seasonal affective disorder symptoms by examining two patients with impaired vision and recurrent winter depressions. The first patient developed winter depressions after developing a traumatic cataract in one eye, and was helped by light therapy. The second patient, fully blind since she was 1 year old, nonetheless suffered as an adult from winter depressions, which responded to bright--but not to dim--light treatment. The authors discuss the implications of these findings.