Nováková M., Praško J., Látalová K., Sládek M., Sumová A. The circadian system of patients with bipolar disorder differs in episodes of mania and depression. Bipolar Disorders 17, 303-314 (2015).

Bipolar disorder patients suffer from disturbances of the sleep-wake cycle. We assessed the functional state of their circadian system by analyzing daily profiles of saliva melatonin and buccal mucosa clock gene expression and compared them with healthy controls. We found that during the episode of depression, there is no difference between controls and patients in both melatonin and clock gene profiles. However, during the mania, the patients have significantly elevated daytime,melatonin levels, higher amplitude of Nr1d1 gene expression and the clock gene expression profiles exhibit a trend towards their phase advance.

A: Elevated daytime levels of saliva melatonin in patients during mania. B: Phase advanced expression of clock gene Per1 (left) and Nr1d1 (right) in patients during mania in comparison with patients during depression