Research interest concerning associations between sleep characteristics and suicidality in psychopathology has been growing. However, possible linkages of suicidality to sleep characteristics in terms of sleep quality and chronotypes among depressive patients have not been well documented. In the current study, the authors investigated the possible effects of sleep quality and chronotype on the severity of depressive symptoms and suicide risk in patients with depressive disorder and healthy controls. The study was conducted on 80 patients clinically diagnosed with major depression and 80 healthy subjects who were demographically matched with the patient group. All participants completed a questionnaire package containing self-report measures, including the Beck Depression Inventory (BDI), Pittsburgh Sleep Quality Index (PSQI), Morningness-Eveningness Questionnaire (MEQ), and Suicide Ideation Scale (SIS), and subjects were interviewed with the suicidality section of the Mini-International Neuropsychiatric Interview (MINI). Results are as follows: (a) logistic regression analyses revealed that poor sleep quality and depression symptom severity significantly predicted onset of major depression; (b) morningness-type circadian rhythm may play as a significant relief factor after onset of major depression; (c) sleep variables of chronotype and sleep quality did not significantly predict suicide ideation after controlling for depressive symptoms in the major depression group; and (d) suicide ideation and poor sleep quality were antecedents of depression symptom severity in patients with major depression, and in healthy controls. Findings are discussed under the theoretical assumptions concerning possible relations between chronotype, sleep quality, depression, and suicidality.

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SUMMAR Y Inconsistent results have been found in the studies evaluating the effect of both total and partial sleep deprivation (SD) on mood in healthy subjects and a few variables have been analyzed as possible predictors. In the present study, we examined whether circadian preference modifies the effect of SD on mood changes in healthy subjects. Sample consisted of 60 healthy volunteers (including 30 morningness and 30 eveningness subjects). Then, the two groups were again divided into two groups for two SD procedures. Fifteen morningness and 15 eveningness chronotypes were total sleep deprived and 15 morningness and 15 eveningness subjects were partial sleep deprived. The mood changes were evaluated before and after SD using Profile of Mood States. Two main results were obtained from our study: a significant increase in depression subscale in morningness chronotypes and a significant decrease in depression subscale score after total SD (TSD) in eveningness chronotypes. The changes in depression-dejection scores of eveningness chronotypes after total (P < 0.01) and partial SD (P < 0.01) were significantly different from changes in morningness chronotypes after TSD. Our results suggest that the effect of SD on mood in normal subjects is related to their circadian preferences. The morningness or eveningness characteristics of the shift workers have significant impact on their mood states. Therefore, adjusting the work schedule with the morningness and eveningness characteristics of the workers may improve their mood alterations.k e y w o r d s circadian, mood, shift work, sleep deprivation

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