In our modern society sleep pathology is often a priority though knowledge is still lacking. This study underlines the impact of chronotypes on the sleep-wake rhythm in depressed patients with insomnia. It is an analytic prospective study on 82 patients with depressive disorder under medical treatment and sleep hygiene recommendations during the whole study. We have found in our study group 39 patients (47,56%) diagnosed with rhythm-based sleep complains before being diagnosed with major depression and we have analyzed the improvements obtained after our intervention. Though antidepressive and hypnoinductive treatment generally brings an adjustment of sleep, it is obvious the need to modify some of the patients habits which are sometimes influenced also by their previous chronobiological type.