The endogenous circadian clock generates daily variations of physiological and behavior functions such as the endogenous interindividual component (morningness/eveningness preferences). Also, mood disorders are associated with a breakdown in the organization of ultradian rhythm. Therefore, the purpose of the present study was to assessed the association between chronotype and the level of depressive symptoms in a healthy sample population. Furthermore, the components of the depression scale that best discriminate the chronotypes were determined.Methods:
This cross-sectional study involved 200 volunteers, aged 18-99 years, 118 women and 82 men. The instruments were the Montgomery-Äsberg Depression Rating Scale (MADRS), the Morningness/Eveningness Questionnaire, the Self-Reporting Questionnaire-20, and the future self-perception questionnaire.Results:
Logistic regression showed that subjects with the eveningness chronotype had a higher chance of reporting more severe depressive symptoms compared to morning- and intermediate-chronotypes, with an odds ratio (OR) of 2.83 and 5.01, respectively. Other independent cofactors associated with a higher level of depressive symptoms were female gender (OR, 3.36), minor psychiatric disorders (OR, 3.70) and low future self-perception (OR, 3.11). Younger age, however, was associated with a lower level of depressive symptoms (OR, 0.97). The questions in the MADRS that presented higher discriminate coefficients among chronotypes were those related to sadness, inner tension, sleep reduction and pessimism.Conclusion:
Identification of an association between evening typology and depressive symptoms in healthy samples may be useful in further investigation of circadian typology and the course of depressive disease.