The ventral tegmental area as a key hub for sleep-wake regulation: A systematic review of cell-type-specific circuits and functional heterogeneity.

The precise regulation of the sleep-wake cycle relies on the coordinated interplay of multiple brain regions, diverse neuronal subtypes, and various neurotransmitter systems. In the neural structures of the midbrain, the ventral tegmental area (VTA) functions as a key neuromodulatory hub. Traditionally, it was thought to regulate reward and motivation primarily; however, recent studies have increasingly established its pivotal role in the sleep-wake rhythm. Based on the VTA's anatomical and cellular heterogeneity, this paper comprehensively summarizes the functional specificity and corresponding circuit mechanisms of dopaminergic (DA), glutamatergic (GLU) and GABAergic (GABA) neurons in sleep-wake regulation. Existing evidence indicates that dopaminergic and glutamatergic neurons jointly form a core arousal-promoting network through their subtype-specific long-range projections. In contrast, GABA neurons facilitate non-rapid eye movement (NREM) sleep and constrain excessive arousal activation via inhibitory projections and local negative feedback loops. Within a unified rhythmic framework, the synergy and counterbalance among these three neuronal subtypes provide a structural basis for the VTA to maintain the stability of sleep-wake states and enable their flexible transition. Furthermore, the interactions between the VTA and other arousal-promoting systems, including orexin, norepinephrine, and serotonin, further expand its functional hierarchy within the whole-brain sleep regulatory network. Meanwhile, circadian modulation of the VTA dopaminergic system maintains sleep-wake and emotional homeostasis. Finally, this paper discusses current limitations in refining neuronal subtypes, causal verification of mechanisms, and clinical translation. It highlights the scientific potential of using the VTA as a target in the management of sleep disorders.