Advanced Circadian Phase in Mania and Delayed Circadian Phase in Mixed Mania and Depression Returned to Normal after Treatment of Bipolar Disorder

Disturbances in circadian rhythms have been suggested as a possible cause of bipolar disorder (BD). Included in this study were 31 mood episodes of 26 BD patients, and 18 controls. Circadian rhythms of BD were evaluated at admission, at 2- week intervals during hospitalization, and at discharge. All participants wore wrist actigraphs during the studies. Saliva and buccal cells were obtained at 8:00, 11:00, 15:00, 19:00, and 23:00 for two consecutive days. Collected saliva and buccal cells were used for analysis of the cortisol and gene circadian rhythm, respectively. Circadian rhythms had different phases during acute mood episodes of BD compared to recovered states. In 23 acute manic episodes, circadian phases were similar to 7 hour advanced (equivalent to similar to 17 hour delayed). Phases of 21 out of these 23 cases returned to normal by similar to 7 hour delay along with treatment, but two out of 23 cases returned to normal by similar to 17 hour advance. In three cases of mixedmanic episodes, the phases were similar to 6-7 hour delayed. For five cases of depressive episodes, circadian rhythms phases were similar to 4-5 hour delayed. After treatment, circadian phases resembled those of healthy controls. Circadian misalignment due to circadian rhythm phase shifts might be a pathophysiological mechanism of BD. (C) 2016 The Authors. Published by Elsevier B.V.