While some CRGs located in the suprachiasmatic nucleus region of the hypothalamus, such as 5-hydroxytryptamine (5-HT), Basic helix-loop-helix ARNT-like protein 1 (BMAL1), Peroxidase 1-3 (Per 1-3), Nuclear receptor subfamily 1 group D member 1 (NR1D1), and D site-binding protein (DBP), have been observed in patients with MDD, the intricate functions of these CRGs pose formidable obstacles to their utilization as potential targets for the prevention, diagnosis, and treatment of the disorder [22, 23]. The gene discussed is NR1D1; the disease is major depressive disorder.