title: Pathophysiological mechanism of seasonal affective disorder.
abstract: Despite the long history in medicine, the pathophysiological mechanism(s) of seasonal affective disorder (SAD) remain largely unknown. By employing a meta-analytic methodology, the authors of this study attempted to verify the validity of different pathophysiological mechanism(s) proposed for SAD. The findings showed that for phototherapy of medium light intensity, a combination of morning-evening therapy regime yielded the best therapeutic effect, and the antidepressant effect of the morning-evening light regime was superior to a single pulse of light administered at other times of day. Furthermore, the data showed that the antidepressant effect of a single pulse of light was similar for morning, midday, and evening light. These findings supported the photon-count hypothesis and refuted the proposed photoperiod, melatonin, and phase-shifting models of SAD.
authors.affiliation: Department of Psychology, University of Hong Kong, Hong Kong. tmclee@hkusua.hku.hk
authors.forename: T M
authors.initials: TM
authors.lastname: Lee
authors.forename: C A
authors.initials: CA
authors.lastname: Blashko
authors.forename: H L
authors.initials: HL
authors.lastname: Janzen
authors.forename: J G
authors.initials: JG
authors.lastname: Paterson
authors.forename: C C
authors.initials: CC
authors.lastname: Chan
mesh_terms: D002940:Circadian Rhythm / Q000502:physiology*; D006801:Humans; D008550:Melatonin / Q000502:physiology*; D010789:Phototherapy; D016574:Seasonal Affective Disorder / Q000503:physiopathology* / Q000523:psychology / Q000628:therapy; D016896:Treatment Outcome
chemical_list: D008550:Melatonin