Recent advances in sleep-wake cycle and biological rhythms in bipolar disorder.

The cyclical nature of periodic switches in energy, motor activation and sleep-wake cycles in bipolar disorder suggests a strong underlying relationship with disturbances in chronobiology. Current research is refining our understanding of the various patterns of sleep-wake and biological rhythms alterations at early and later stages of this illness, as well as across its depressive/fatigue, manic/hypomanic and euthymic phases. This research focuses on early detection and subsequent monitoring to predict and better manage recurrent episodes. Sleep-wake cycle and biological rhythms disturbances are also well known to affect other key aspects of physical health (notably metabolic functions), cognitive performance and elevated risks for suicide. Increasing evidence now supports the integration of behavioural or pharmacological therapeutic strategies that target the sleep-wake and circadian systems in the ongoing treatment of various phases of bipolar disorder.