SLEEP DISTURBANCES IN MAJOR DEPRESSIVE DISORDER: A COMPREHENSIVE NARRATIVE REVIEW

Objectives: To review and synthesize current evidence on the characteristics, underlying mechanisms, and clinical significance of sleep disturbances in Major Depressive Disorder (MDD). Methods: A narrative review of thirty peer-reviewed articles published between 2010 and 2025 was conducted. The included studies investigated sleep architecture, circadian rhythms, neurobiological mechanisms, and therapeutic interventions related to sleep disturbances in MDD using neuroimaging, electrophysiological, molecular, and clinical approaches. Results: The reviewed literature indicates that sleep disturbances are a core feature of MDD. The most consistently reported abnormalities include shortened rapid eye movement (REM) latency, reduced slow-wave sleep, and circadian rhythm dysregulation. These alterations are associated with dysfunctions of monoaminergic neurotransmission, hyperactivity of the hypothalamic-pituitary-adrenal axis, and disruptions of circadian clock gene regulation. Sleep disturbances were also linked to impairments in emotional regulation, cognitive functioning, metabolic processes, and treatment response. Sleep-focused interventions, including cognitive-behavioral therapy for insomnia, chronotherapy, and light-based treatments, demonstrated antidepressant effects. Conclusions: Sleep disturbances play a fundamental role in the pathophysiology and clinical course of MDD. Addressing sleep-related mechanisms may improve diagnostic accuracy, enhance treatment effectiveness, and contribute to better long-term outcomes in patients with depression.