FIGURE 3.

Schematic of the bidirectional relationship of dopamine signaling with sleep and circadian rhythm disruption (SCRD). The dopamine (DA) system is involved in sleep-wake control and circadian rhythms, therefore aberrant DA signaling will result in disruption to sleep and circadian rhythms. On the other hand, DA is also under the control of the circadian clock and its activity varies with sleep stage, therefore SCRD, arising from dysregulation of the DA system itself, or genetic or environmental factors, will aberrantly impact DA signaling. Dysregulation to each of these systems will exacerbate each other; disturbances to one will worsen abnormalities in the other, forming a positive feedback cycle. This process may be an important mechanism underlying schizophrenia pathogenesis and progression of the illness.