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.

睡眠障碍和皮质醇觉醒反应（CAR）的变化是重度抑郁症（MDD）发病率的潜在预测因素。然而，这些参数通常是单独评估的，缺乏关于睡眠障碍和 CAR 同时关联的信息，主要是在整个 MDD 严重程度中。本研究探讨了初始/轻度抑郁症患者（MD，n = 30）与晚期/难治性抑郁症患者（TRD，n = 28）的睡眠质量和 CAR 之间的关系，并与一组健康对照组（CG，n = 28）进行比较。 49），旨在从临床角度指出在重度抑郁症严重程度阶段观察到的睡眠和 CAR 的变化。与 MD 组和 CG 组相比，TRD 患者的 CAR 较弱，睡眠质量较差。此外，与 CG 患者相比，MD 患者的睡眠质量更差，CAR 更大。总而言之，睡眠质量和 CAR 都与 MDD 症状和 MDD 严重程度的预测因素相关，对睡眠质量具有更大的分类能力。具体来说，从睡眠质量来看，睡眠药物的使用和睡眠效率可以预测抑郁症的严重程度，从而区分轻度抑郁症和难治性抑郁症。这些结果表明，当需要在临床背景下评估重度抑郁症的严重程度时，评估重度抑郁症患者的睡眠质量和 CAR 非常重要。CAR 和睡眠质量可以作为有用的补充工具，帮助临床识别重度抑郁症的严重程度，了解它们对 MDD 的影响可能支持进一步的研究，旨在改进干预策略，以提高治疗的有效性。