Mechanism of the anterior cingulate cortex in sleep regulation.

Sleep disorders refer to conditions characterized by abnormal sleep duration and quality, including insomnia, sleep-disordered breathing, and fragmented sleep, and have become one of the major challenges to modern physical and mental health. The anterior cingulate cortex (ACC) is an important component of the limbic system, located between the cingulate sulcus and the callosal sulcus on the medial surface of the cerebral hemispheres, and plays a critical role in regulating autonomic movements, emotions, and pain. It is an important part of the sleep regulation system. In patients with primary insomnia, reduced sleep duration is associated with lower levels of gamma-aminobutyric acid in the ACC, and these patients often exhibit increased ACC volume and altered functional structure. The ACC is recognized as a central region for pain perception and the regulation of negative emotions; it participates in the control of chronic pain and regulates pain-related insomnia via descending projections. Moreover, the ACC is a key area in the pathophysiology of major depressive disorder, where individuals with depression or poor sleep quality show enhanced functional connectivity between the ACC and regions such as the lateral orbitofrontal cortex, posterior cingulate cortex, precuneus, angular gyrus, and temporal cortex. Abnormal functional connectivity within ACC subregions is implicated in anhedonia and impaired sleep quality in patients with major depressive disorder.