[Seasonal affective disorders, a new clinical category]

Seasonal affective disorders have recently been individualized by American authors. According to these authors, this subgroup of affective diseases deserve to be regarded as a clinical category owing to its specific symptoms, its epidemiological features and its response to treatment. They are characterized by the triad: hypersomnia, hyperoxia, weight gain, associated with usual symptoms of depression. Moreover, contrary to the bipolar manic-depressive psychosis, they seem to predominate among women. Finally, phototherapy, the various protocols of which are discussed here, is said to be effective. The influence of latitude combined with the effectiveness of phototherapy has led to original pathogenic hypotheses, among which the presence of a chronobiological disorder (abnormality of the season-induced circadian rhythm), although attractive and supported by a strict clinical study, has yet to be demonstrated. Also hypothetical is the role played by melatonin: is this hormone the principal "mediator" or an epiphenomenon?