[Disorders of circadian rhythms in depression]

The authors make a synthesis of studies about circadian rhythms in depression and of hypothesis to explain them. They successively study trials on the phases, on the average levels, on the amplitude of rhythms. They conclude the most significant troubles are, shortening of latency on paradoxical sleep for phases, slump of melatonin levels, blunded amplitude of every parameter. Among possible explanations, they present and discuss a trouble of oscillators, a decrease of sensitivity to external synchronizers and a trouble in rhythm coupling.