Keeping Time: Investigating the relationship between circadian rhythm and mood disorders via precise circadian measurement techniques

Disruptions in circadian rhythms and sleep have long been associated with mood disorders. In fact, sleep disturbances are one of the key features used in the DSM-V diagnosis of major depressive disorder and bipolar disorder. Sleep/wake abnormalities can also precede mood episodes and predict treatment response. Thus, precise measurement of specific sleep/circadian features is important as these measures can be used clinically to direct appropriate treatments. These measures can also be used for research purposes to try to understand specific mechanisms by which circadian rhythm disturbances and sleep/wake perturbations may lead to specific phenotypes. The purpose of this review is to highlight recent advances in methodology which can be used to more precisely measure sleep/circadian biology. This review will examine how these new methodologies can better elucidate the mechanisms linking sleep/circadian disruptions and mood disorders, as well as how new technologies can be used therapeutically to treat sleep/circadian abnormalities.