CD4 and major depressive disorder: Nevertheless, the potential relationship between sleep disturbance and lymphocyte subpopulations characteristic in patients with MDD remains underexplored.<h4>Methods</h4>In this study, flow cytometry was used to measure the proportion of peripheral blood CD4<sup>+</sup> T-helper cells in 63 patients with MDD and 60 age- and sex-matched healthy controls (HCs).