A Circadian Signal of Change of Season in Patients With Seasonal Affective Disorder

Abstract

SEASONAL AFFECTIVE disorder (SAD), characterized by recurrent episodes of winter depression, is a common problem and a significant source of distress for those living in temperate and boreal regions.^1,2 Symptoms of SAD, which include weight gain, increased sleep, decreased activity, and loss of interest in sex, resemble seasonal changes that occur in other mammals. Such changes in mammals have been shown to occur in response to seasonal changes in sunlight.³ The same seems to be true of SAD inasmuch as it responds to treatment with light.^4-8