The circadian neurobiology of reward.

Circadian clocks are important regulators of physiology and behaviour. In the brain, circadian clocks have been described in many centres of the central reward system. They affect neurotransmitter signalling, neuroendocrine circuits, and the sensitivity to external stimulation. Circadian disruption affects reward signalling, promoting the development of behavioral and substance use disorders. In this review we summarize our current knowledge of circadian clock-reward crosstalk. We show how chronodisruption affects reward signalling in different animal models. We then translate these findings to circadian aspects of human reward (dys-) function and its clinical implications. Finally, we devise approaches to and challenges in implementing the concepts of circadian medicine in the therapy of substance use disorders.