Relationship between social rhythms and mood in patients with rapid cycling bipolar disorder

Disruptions in the sleep-wake cycle frequently characterize affective illne ss and have led to a number of theories linking sleep-wake and/or circadian rhythm disturbance to affective illness. Recently, researchers have expand ed these chronobiological theories to include the role of lifestyle regular ity, or daily social rhythms. In this study, the Social Rhythm Metric (SRM) was used to explore the relationship between social rhythms and mood in pa tients with rapid cycling bipolar disorder and to compare the social rhythm s of patients with those of healthy control subjects. Patients' SRM scores and activity level indices were significantly lower than those of control s ubjects. In addition, the timing of five, mostly morning, activities was ph ase delayed in patients compared to control subjects. Patients also demonst rated a phase delay in the timing of morning activities during depression c ompared to hypomania or euthymia. The phase changes in the timing of mornin g activities are consistent with other data implicating morning zeitgebers in the pathophysiology of rapid cycling bipolar disorder. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.