The Chi-square statistics reveals a significant association of PSMD9 SNP rs74421874 (IVS3+nt460G>A) and SNP rs3825172 (IVS3+nt437C>T), independently, with insomnia using anxiety as covariate (p-value = 0.029), but not using depression as covariate (p-value = 0.10). Here, PSMD9 is linked to major depressive disorder.