The effect of optimism on depression: the mediating and moderating role of insomnia.

This article aims to clarify if insomnia exerts a mediating or moderating effect on the optimism-depression association in Chinese college students. 529 Chinese college students completed the Beck Depression Inventory (BDI-II), the Pittsburgh Sleep Quality Index (PSQI), the Revised Life Orientation Test (LOT-R) and the Multidimensional Scale of Social Support (MSPSS). The results failed to show any moderating effect but after adjustment for age, gender and social support, a mediating effect was observed. In conclusion, insomnia qualifies as a mediator, suggesting considerable variance in depressive symptoms of college students could be due to change in their sleep status.