title: Biological rhythm differences and suicidal ideation in patients with major depressive disorder.
abstract: BACKGROUND
  Suicidal behavior has been reported to be associated with seasonality and chronotype. However, no study has reported the suicidality according to chronotype and seasonality in patients with major depressive disorder (MDD). This study evaluated the relationship of suicidality and biological rhythm in patients with MDD.
  
  
  METHODS
  A total of 120 patients with MDD participated. We evaluated their seasonal patterns, chronotypes (morningness, wake up early and are at their best during the first part of the day; eveningness, feel best and most alert during late hours), suicidal ideations, and other clinical variables including symptom severity.
  
  
  RESULTS
  Patients with seasonality showed significantly higher suicidal ideation than patients without seasonality. Compared to morning-type participants, the evening-type participants showed higher suicidality. Suicidal ideation was positively correlated with eveningness tendencies and hypomanic personality traits.
  
  
  CONCLUSIONS
  First, we did not analyze the causal relationship between biological rhythm and suicidality. Secondly, suicidal ideation does not in most cases reflect an actual attempt. Lastly, we did not categorize seasonal pattern into summer or winter type.
  
  
  CONCLUSIONS
  Our findings suggest that biological rhythm is significantly associated with suicidal ideation in patients with MDD.
authors: Clinical Emotion and Cognition Research Laboratory, Inje University, Goyang, Republic of Korea; Department of Psychology, Korea University, Seoul, Republic of Korea.
authors: Yong-Chun
authors: YC
authors: Bahk
authors: Department of Psychology, Duke University, Durham, United States.
authors: Esther
authors: E
authors: Han
authors: Clinical Emotion and Cognition Research Laboratory, Inje University, Goyang, Republic of Korea; Department of Psychiatry, Inje University College of Medicine, Ilsan Paik Hospital, Juhwa-ro 170, Ilsanseo-gu, Goyang, 411-706 Republic of Korea. Electronic address: lshpss@paik.ac.kr.
authors: Seung-Hwan
authors: SH
authors: Lee
mesh_terms: D000328:Adult; D002940:Circadian Rhythm; D003865:Major Depressive Disorder / Q000503:physiopathology* / Q000523:psychology*; D005260:Female; D006801:Humans; D008297:Male; D012621:Seasons; D059020:Suicidal Ideation
keywords: Biological rhythm; Chronotype; Major depressive disorder; Seasonal affective disorder; Seasonality; Suicidality