title: Chronotype distribution in bipolar I disorder and schizophrenia in a Korean sample.
abstract: OBJECTIVE
  Although a broad range of circadian rhythm variations have been reported, analyses of chronotypes in bipolar I disorder (BDI) and schizophrenia are rare. The present study aimed to investigate specific chronotype patterns in BDI and schizophrenia compared with healthy subjects.
  
  
  METHODS
  All patients were clinically stable and recruited from the outpatient clinics of Seoul National University Hospital. They were diagnosed according to DSM-IV criteria. 'Morningness/eveningness', a chronotype correlated with circadian phase, was evaluated using the Composite Scale of Morningness (CSM) among 92 patients with BDI, 113 patients with schizophrenia (SZ), and 95 control individuals.
  
  
  RESULTS
  The CSM scores were significantly correlated with age in the control group, but a significant correlation with age was not observed in the schizophrenia or BDI groups. After controlling for age, there were significant differences between the BDI and control groups. The SZ patients did not differ from the BDI or control groups.
  
  
  CONCLUSIONS
  In this Korean sample, patients with BDI showed a significantly greater preference for 'eveningness' (including delayed sleep timing) than control individuals. The influences of pharmacotherapy or clinical status on CSM scores need to be clarified.
authors.affiliation: Department of Psychiatry and Behavioral Science and Institute of Human Behavioral Medicine, Seoul National University College of Medicine, Seoul, South Korea.
authors.forename: Yong Min
authors.initials: YM
authors.lastname: Ahn
authors.forename: Jaeseung
authors.initials: J
authors.lastname: Chang
authors.forename: Yeon Ho
authors.initials: YH
authors.lastname: Joo
authors.forename: Seong Chan
authors.initials: SC
authors.lastname: Kim
authors.forename: Kyu Young
authors.initials: KY
authors.lastname: Lee
authors.forename: Yong Sik
authors.initials: YS
authors.lastname: Kim
mesh_terms: D000328:Adult; D000553:Ambulatory Care; D044466:Asian People / Q000706:statistics & numerical data*; D001714:Bipolar Disorder / Q000175:diagnosis / Q000208:ethnology* / Q000628:therapy; D021081:Chronobiology Disorders / Q000175:diagnosis / Q000208:ethnology*; D039721:Diagnostic and Statistical Manual of Mental Disorders; D005260:Female; D006801:Humans; D008297:Male; D015995:Prevalence; D012189:Retrospective Studies; D012559:Schizophrenia / Q000175:diagnosis / Q000208:ethnology* / Q000628:therapy; D012720:Severity of Illness Index; D011795:Surveys and Questionnaires