title: Delayed sleep phase in young people with unipolar or bipolar affective disorders.
abstract: BACKGROUND
  Circadian disturbances may play a key role in the pathogenesis of some forms of mood disorders. Despite marked changes in circadian rhythms during the normal course of adolescence and young adulthood, less is known about changes in the 24-h sleep-wake cycle in young persons with mood disorders.
  
  
  METHODS
  Seventy-five young participants with mood disorders (unipolar: n=46, 20.1 ± 4.7 years old; bipolar I or II: n=29, 23.2 ± 4.3) and 20 healthy participants (24.8 ± 2.5 years old) underwent actigraphy monitoring during a depressive phase over seven consecutive days and nights. Sleep phase delay was defined as mean sleep onset ≥ 1:30 am and/or sleep offset ≥ 1 0:00 am.
  
  
  RESULTS
  A delayed sleep phase was found in 62% of participants with bipolar disorders when depressed, compared with 30% of those with unipolar depression (χ(2)=6.0, p=0.014) and 10% of control participants (χ(2)=11.2, p<0.001). Sleep offset times were significantly later in subjects with mood disorders compared to the control group, and later in those with bipolar as compared with unipolar disorders (all p ≤ 0.043).
  
  
  CONCLUSIONS
  This study was cross-sectional and the depressed groups were somewhat younger compared to the healthy controls. Longitudinal studies are required to determine the predictive significance of these findings.
  
  
  CONCLUSIONS
  Young patients with mood disorders, especially those with bipolar disorders, are particularly likely to have a delayed sleep phase. Therapies focused on advancing sleep phase may be of specific benefit to these young persons.
authors.affiliation: Clinical Research Unit, Brain & Mind Research Institute, University of Sydney, New South Wales, Australia.
authors.forename: Rébecca
authors.initials: R
authors.lastname: Robillard
authors.forename: Sharon L
authors.initials: SL
authors.lastname: Naismith
authors.forename: Naomi L
authors.initials: NL
authors.lastname: Rogers
authors.forename: Tony K C
authors.initials: TK
authors.lastname: Ip
authors.forename: Daniel F
authors.initials: DF
authors.lastname: Hermens
authors.forename: Elizabeth M
authors.initials: EM
authors.lastname: Scott
authors.forename: Ian B
authors.initials: IB
authors.lastname: Hickie
mesh_terms: D000293:Adolescent; D000328:Adult; D001714:Bipolar Disorder / Q000453:epidemiology* / Q000503:physiopathology; D016022:Case-Control Studies; D002940:Circadian Rhythm / Q000502:physiology; D003430:Cross-Sectional Studies; D003866:Depressive Disorder / Q000453:epidemiology* / Q000503:physiopathology; D005260:Female; D006801:Humans; D008297:Male; D012893:Sleep Wake Disorders / Q000453:epidemiology*; D055815:Young Adult