Figure 1.

Illustration of the Integrated Sleep and Reward (ISR) model.

Dashed lines indicate early developmental processes. Bolded ovals indicate primary sleep disturbance/reward processing pathways of the ISR model. Rectangles indicate moderators (dark shade) of the sleep/reward relationship and additional mediational pathways (light shade) through which the interaction of sleep disturbance and reward processing may lead to depression. In this model, an individual may experience sleep disturbance during early childhood, influencing concurrently developing neural pathways in the reward system (a). This may lead to reduced trait level striatal activity, which may strengthen the relationship between sleep disturbance and reward processing (b). Sleep mediated reward deficits may directly lead to depression, or may influence the development of negative mood states or behaviors that may more proximally lead to the development of MDD (c and d).