MAIN TEXT
Individuals differ widely in their reward- and drug-craving behaviors. One reason for these differences involves sleep. Sleep disturbances lead to an increased risk of substance use disorders and relapse in some, but not all, individuals. There is considerable individual variation in the cognitive and emotional responses to sleep deprivation (SD) and how SD alters the motivation for food or drug reward. The precise neural circuits explaining this individual variation remain poorly understood. While animal studies have examined the general impact of sleep on reward circuitry, few have addressed the role of individual differences in the effects of altered sleep. There does, however, exist a robust preclinical rodent model of individual differences in reward-seeking behavior. In this model, only some rats show heightened cue-induced dopamine activity, resulting in hyper-sensitivity to the motivational effects of cues. This subset of rats also shows many of the key behavioral traits associated with addiction, including increased impulsivity and poor attentional control. Other rats do not show these addiction-related tendencies, making this an ideal model system in which to study the relationship between altered sleep and individually distinct reward-seeking behaviors. In this review, we support this argument by describing how the limbic neural circuits responsible for individual differences in incentive motivation closely overlap with those involved in sleep-wake regulation. Consideration of these individual differences in preclinical models would improve our understanding of how sleep interacts with motivational systems, and why sleep deprivation contributes to reward-seeking behavior and addiction in only a select group of individuals.