Use of sleep quality questionary and cortisol awakening response as complementary tools for the evaluation of major depression progression

Sleep disorders and changes in the profile of the cortisol awakening response (CAR) are potential predictive factors for the incidence of major depressive disorder (MDD). However, these parameters usually are evaluated separately, lacking information regarding the simultaneous association of sleep disorders and CAR, mainly throughout the MDD severity. This study addressed the relationship between sleep quality and CAR in patients with initial/mild depression (MD, n = 30) versus advanced/treatment-resistant (TRD, n = 28), compared with a group of healthy controls (CG, n = 49), aiming to point out in a clinical perspective which alterations in sleep and CAR have been observed along major depression severity stages. TRD patients presented a blunted CAR and poorer sleep quality comparing MD and CG groups. Additionally, MD patients showed worse sleep quality and larger CAR than CG. Taken together, both sleep quality and CAR were correlated with MDD symptoms and predictors of MDD severity, with a greater classification power for sleep quality. From sleep quality, specifically, the use of sleep medication and sleep efficiency predicted depression severity, discriminating mild and treatment-resistant depression. These results show the importance of assessing sleep quality and CAR in patients with major depression when there is a need for evaluation of the disorder’s severity in a clinical context. CAR and sleep quality can be useful complementary tools to help in the clinical identification of major depression severity and the understanding of their impact on MDD may support further studies that aim to improve intervention strategies to increase the effectiveness of treatments.