Social jetlag and depression status: Results obtained from the Netherlands Study of Depression and Anxiety.

Social jetlag, the misalignment between the internal clock and the socially required timing of activities, is highly prevalent, especially in people with an evening chronotype and is hypothesized to be related to the link between the evening chronotype and major depressive disorder. Although social jetlag has been linked to depressive symptoms in non-clinical samples, it has never been studied in patients with major depressive disorder (MDD). This study is aimed to study social jetlag in patients with major depressive disorder and healthy controls, and to further examine the link between social jetlag and depressive symptomatology. Patients with a diagnosis of MDD (n=1084) and healthy controls (n=385), assessed in a clinical interview, were selected from the Netherlands Study of Depression and Anxiety. Social jetlag was derived from the Munich Chronotype Questionnaire, by calculating the absolute difference between the midsleep on free days and midsleep on work days. Depression severity was measured with the Inventory of Depressive Symptomatology. It was found that patients with MDD did not show more social jetlag compared to healthy controls, neither in a model without medication use (beta=0.06, 95% CI: -0.03-0.15, p=0.17) nor in a model where medication use is accounted for. There was no direct association between the amount of social jetlag and depressive symptoms, neither in the full sample, nor in the patient group or the healthy control group. This first study on social jetlag in a clinical sample showed no differences in social jetlag between patients with MDD and healthy controls.