title: The role of disturbed sleep in the early recognition of bipolar disorder: a systematic review.
abstract: OBJECTIVE
  Severely disturbed sleep is known to occur during and shortly prior to the onset of mood episodes in bipolar disorder. Whether alterations in sleep occur parallel and as part of the disease process or whether they represent a trait existent before the onset of the disorder itself remains unclear.
  
  
  METHODS
  A systematic review evaluating all published data on the occurrence of disordered sleep prior to the onset of the first mood episode was conducted.
  
  
  RESULTS
  The evidence cited within this paper suggests that sleep disturbances frequently precede bipolar disorder by several years and convey an elevated long-term risk for developing any kind of mood disorder. Disordered sleep appears to emerge about the time of puberty and remains persistently elevated in individuals at high risk.
  
  
  CONCLUSIONS
  Disturbed sleep appears to be an early symptom of bipolar disorder but further research, especially longitudinal studies in individuals at high risk, will be required to characterize the type and patterns more precisely.
authors.affiliation: Klinik und Poliklinik für Psychiatrie und Psychotherapie, Universitätsklinikum Carl Gustav Carus, Dresden, Germany. philipp.ritter@uniklinikum-dresden.de
authors.forename: Philipp S
authors.initials: PS
authors.lastname: Ritter
authors.forename: Carolin
authors.initials: C
authors.lastname: Marx
authors.forename: Michael
authors.initials: M
authors.lastname: Bauer
authors.forename: Karolina
authors.initials: K
authors.lastname: Leopold
authors.forename: Karolina
authors.initials: K
authors.lastname: Lepold
authors.forename: Andrea
authors.initials: A
authors.lastname: Pfennig
mesh_terms: D001714:Bipolar Disorder / Q000175:diagnosis* / Q000453:epidemiology*; D016208:Databases, Factual / Q000706:statistics & numerical data; D006801:Humans; D008137:Longitudinal Studies; D012189:Retrospective Studies; D012893:Sleep Wake Disorders / Q000453:epidemiology*