title: An actigraphy study investigating sleep in bipolar I patients, unaffected siblings and controls.
abstract: Disturbances in sleep and waking patterns are highly prevalent during mood episodes in bipolar disorder. The question remains whether these disturbances persist during phases of euthymia and whether they are heritable traits of bipolar disorder. The current study investigates objective sleep measures in a large sample of bipolar I patients, non-affected siblings and controls.
  
  
  
  A total of 107 bipolar disorder I patients, 74 non-affected siblings, and 80 controls were included. Sleep was measured with actigraphy over the course of 14 days. Seven sleep parameters were analyzed for group differences and their relationship with age at onset, number of episodes and psychotic symptoms using linear mixed model analysis to account for family dependencies.
  
  
  
  Patients had a longer sleep duration and later time of sleep offset compared to the non-affected siblings but these differences were entirely attributable to differences in mood symptoms. We found no difference between patients and controls or siblings and controls when the analyses were restricted to euthymic patients. None of the bipolar illness characteristics were associated with sleep.
  
  
  
  Medication use was not taken into account which may have influenced our findings and controls were younger compared to non-affected siblings.
  
  
  
  In the largest study to date, our findings suggest that recovered bipolar I patients and their siblings do not experience clinically significant sleep disturbances. Sleep disturbances are primarily a reflection of current mood state, but are unrelated to the course of the disorder.
authors: Department of Psychiatry, Brain Center Rudolf Magnus, University Medical Center Utrecht, Utrecht, The Netherlands. Electronic address: S.Verkooijen@umcutrecht.nl.
authors: Sanne
authors: S
authors: Verkooijen
authors: Department of Psychiatry, Brain Center Rudolf Magnus, University Medical Center Utrecht, Utrecht, The Netherlands.
authors: Annet H
authors: AH
authors: van Bergen
authors: Department of Psychiatry, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.
authors: Stefan E
authors: SE
authors: Knapen
authors: Department of Psychiatry, Brain Center Rudolf Magnus, University Medical Center Utrecht, Utrecht, The Netherlands; Netherlands Institute of Mental Health and Addiction (Trimbos Institute), Drug Information and Monitoring System, Department of Drug Monitoring, Utrecht, The Netherlands; Department of Psychology, Leiden University, Leiden, The Netherlands.
authors: Annabel
authors: A
authors: Vreeker
authors: Department of Psychiatry, Brain Center Rudolf Magnus, University Medical Center Utrecht, Utrecht, The Netherlands.
authors: Lucija
authors: L
authors: Abramovic
authors: Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX, USA.
authors: Lucia
authors: L
authors: Pagani
authors: Center for Neurobehavioral Genetics, University of California Los Angeles, Los Angeles, CA, USA.
authors: Yoon
authors: Y
authors: Jung
authors: Department of Psychiatry, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands; Lentis FACT, Winschoten, The Netherlands.
authors: Rixt
authors: R
authors: Riemersma-van der Lek
authors: Department of Psychiatry, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.
authors: Robert A
authors: RA
authors: Schoevers
authors: Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX, USA; Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX, USA.
authors: Joseph S
authors: JS
authors: Takahashi
authors: Department of Psychiatry, Brain Center Rudolf Magnus, University Medical Center Utrecht, Utrecht, The Netherlands.
authors: René S
authors: RS
authors: Kahn
authors: Department of Psychiatry, Brain Center Rudolf Magnus, University Medical Center Utrecht, Utrecht, The Netherlands.
authors: Marco P M
authors: MPM
authors: Boks
authors: Department of Psychiatry, Brain Center Rudolf Magnus, University Medical Center Utrecht, Utrecht, The Netherlands; Center for Neurobehavioral Genetics, University of California Los Angeles, Los Angeles, CA, USA.
authors: Roel A
authors: RA
authors: Ophoff
mesh_terms: D056044:Actigraphy; D000328:Adult; D000339:Affect; D001714:Bipolar Disorder / Q000150:complications / Q000503:physiopathology*; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D017286:Polysomnography; D035781:Siblings; D012890:Sleep; D012893:Sleep Wake Disorders / Q000235:genetics / Q000523:psychology*
keywords: Actigraphy; Bipolar disorder; Sleep disturbances