Circadian rhythms and sleep in bipolar disorder.

OBJECTIVE: Biological rhythm pathways are highlighted in a number of etiological models of bipolar disorder, and the management of circadian instability appears in consensus treatment guidelines. There are, however, significant conceptual and empirical limitations on our understanding of a hypothesised link between circadian, sleep, and emotion regulation processes in bipolar disorder. The aim of this article is to articulate the limits of scientific knowledge in relation to this hypothesis.

METHODS: A critical evaluation of various literatures was undertaken. The basic science of circadian and sleep processes, their involvement in normal emotion regulation, and the types of evidence suggesting circadian/sleep involvement in bipolar disorder are reviewed.

RESULTS: Multiple lines of evidence suggest that circadian and sleep-wake processes are causally involved in bipolar disorder. These processes demonstrably interact with other neurobiological pathways known to be important in bipolar disorder, but are unique in that they are open to behavioural manipulation.

CONCLUSION: Further research into biological rhythm pathways to bipolar disorder is warranted. Person-environment feedback loops are fundamental to circadian adaptation, and models of circadian pathogenesis (and treatment) should recognize this complexity.