Chronotype distribution in bipolar I disorder and schizophrenia in a Korean sample.
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.
Ahn
Yong Min
YM
Department of Psychiatry and Behavioral Science and Institute of Human Behavioral Medicine, Seoul National University College of Medicine, Seoul, South Korea.
Chang
Jaeseung
J
Joo
Yeon Ho
YH
Kim
Seong Chan
SC
Lee
Kyu Young
KY
Kim
Yong Sik
YS
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