title: Delayed sleep phase: An important circadian subtype of sleep disturbance in bipolar disorders.
abstract: BACKGROUND
  Theoretical models of Bipolar Disorder (BD) highlight that sleep disturbances may be a marker of underlying circadian dysregulation. However, few studies of sleep in BD have reported on the most prevalent circadian sleep abnormality, namely Delayed Sleep Phase (DSP).
  
  
  METHODS
  A cross-sectional study of 404 adults with BD who met published clinical criteria for insomnia, hypersomnia or DSP, and who had previously participated in a study of sleep in BD using a comprehensive structured interview assessment.
  
  
  RESULTS
  About 10% of BD cases with a sleep problem met criteria for a DSP profile. The DSP group was younger and had a higher mean Body Mass Index (BMI) than the other groups. Also, DSP cases were significantly more likely to be prescribed mood stabilizers and antidepressant than insomnia cases. An exploratory analysis of selected symptom item ratings indicated that DSP was significantly more likely to be associated with impaired energy and activity levels.
  
  
  CONCLUSIONS
  The cross-sectional design precludes examination of longitudinal changes. DSP is identified by sleep profile, not by diagnostic criteria or objective sleep records such as actigraphy. The study uses data from a previous study to identify and examine the DSP group.
  
  
  CONCLUSIONS
  The DSP group identified in this study can be differentiated from hypersomnia and insomnia groups on the basis of clinical and demographic features. The association of DSP with younger age, higher BMI and impaired energy and activity also suggest that this clinical profile may be a good proxy for underlying circadian dysregulation.
authors.affiliation: Department of Neuroscience, Faculty of Medicine, Norwegian University of Science and Technology & Department of Psychiatry, St. Olavs University Hospital, Trondheim, Norway.
authors.forename: Mette Kvisten
authors.initials: MK
authors.lastname: Steinan
authors.affiliation: Department of Neuroscience, Faculty of Medicine, Norwegian University of Science and Technology & Department of Psychiatry, St. Olavs University Hospital, Trondheim, Norway.
authors.forename: Gunnar
authors.initials: G
authors.lastname: Morken
authors.affiliation: NORMENT, KG Jebsen Centre for Psychosis Research, Oslo University Hospital, Oslo, Norway.
authors.forename: Trine V
authors.initials: TV
authors.lastname: Lagerberg
authors.affiliation: NORMENT, Institute of Clinical Medicine, University of Oslo, & NORMENT Division of Mental Health and Addiction, Oslo University Hospital, Oslo, Norway.
authors.forename: Ingrid
authors.initials: I
authors.lastname: Melle
authors.affiliation: NORMENT, KG Jebsen Centre for Psychosis Research, Division of Mental Health and Addiction, Oslo University Hospital & Institute of Clinical Medicine, University of Oslo, Norway.
authors.forename: Ole A
authors.initials: OA
authors.lastname: Andreassen
authors.affiliation: Department of Neuroscience, Faculty of Medicine, Norwegian University of Science and Technology & Department of Psychiatry, St. Olavs University Hospital, Trondheim, Norway.
authors.forename: Arne E
authors.initials: AE
authors.lastname: Vaaler
authors.affiliation: Academic Psychiatry, Institute of Neuroscience, Newcastle University, Centre for Affective Disorders, Institute of Psychiatry, London, United Kingdom. Electronic address: jan.scott@newcastle.ac.uk.
authors.forename: Jan
authors.initials: J
authors.lastname: Scott
mesh_terms: D000328:Adult; D000367:Age Factors; D000928:Antidepressive Agents / Q000627:therapeutic use; D001714:Bipolar Disorder / Q000150:complications* / Q000188:drug therapy; D015992:Body Mass Index; D003430:Cross-Sectional Studies; D006970:Disorders of Excessive Somnolence / Q000209:etiology / Q000503:physiopathology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012890:Sleep / Q000502:physiology; D020178:Sleep Disorders, Circadian Rhythm / Q000209:etiology* / Q000503:physiopathology; D007319:Sleep Initiation and Maintenance Disorders / Q000209:etiology / Q000503:physiopathology
chemical_list: D000928:Antidepressive Agents
keywords: Bipolar Disorders; Delayed Sleep Phase; Sleep; Sleep Disturbance