On the chronobiology of seasonal affective disorder

Chronobiological hypotheses about the pathogenesis of affective disorders have a long history. According to the modern variants, abnormalities of either a sleep-wake cycle dependent process S, or a circadian pacemaker related process C, or an abnor-mal interaction between these two processes underlie the pathogenesis of depres-sion. However, up till now, research did not yield consistent support for these theo-ries. The development of the forced desynchrony protocol for the study of the human circadian system and the observed effects of extraocular light stimuli on this system offered the opportunity to reinvestigate this issue. In this thesis these opportunities have been utilized to test chronobiological hypotheses in winter-type Seasonal Affective Disorder.