title: A Retrospective Examination of Sleep Disturbance across the Course of Bipolar Disorder.
abstract: BACKGROUND
  Sleep disturbance is a prevalent and clinically significant feature of bipolar disorder. However, there are aspects of sleep and bipolar disorder that have been minimally characterized. This study aims to fill several gaps in the literature by examining the prevalence, coexistence, and persistence of sleep disturbance retrospectively across a five-year period in bipolar disorder.
  
  
  METHODS
  Fifty-one people with bipolar disorder I and comorbid insomnia who were currently inter-episode completed the NIMH Retrospective Life-Charting Methodology (the life chart). The life chart was used to document the prevalence, coexistence, and persistence of insomnia, hypersomnia, delayed sleep phase, reduced sleep need, and irregular sleep patterns across the course of five years.
  
  
  RESULTS
  Across the five year period, manic months were primarily characterized by reduced sleep need (62.8%) and insomnia (38.1%), depressive months by hypersomnia (56.0%) and insomnia (51.9%), mixed months by all five types of sleep disturbance, and inter-episode months by insomnia (67.4%). There was coexistence in the types of sleep disturbance experienced. Further, each type of sleep disturbance demonstrated persistence across the five years, with persistence rates being the highest for insomnia (49.0-58.8%).
  
  
  CONCLUSIONS
  Sleep disturbance is a prevalent and complex feature across mood episodes and inter-episode periods of bipolar disorder. Further, there is variation in the types of sleep disturbance experienced.
authors.affiliation: Department of Psychology, University of California, Berkeley, Berkeley, CA, USA.
authors.forename: Jennifer C
authors.initials: JC
authors.lastname: Kanady
authors.affiliation: Department of Psychiatry, University of Pittsburgh, School of Medicine, Pittsburgh, PA, USA.
authors.forename: Adriane M
authors.initials: AM
authors.lastname: Soehnera
authors.affiliation: Department of Psychology, University of California, Berkeley, Berkeley, CA, USA.
authors.forename: Allison G
authors.initials: AG
authors.lastname: Harvey
keywords: Bipolar disorder; Coexistence; Persistence; Prevalence; Sleep disturbance