With this in mind we sought to characterize the kinetic features of various “dual” orexin receptor antagonists at OX1R and OX2R. We selected antagonists that have either been used clinically or are currently under development for the treatment of insomnia and sleep disorders, including almorexant, SB-649868, suvorexant, and filorexant. This evidence concerns the gene HCRTR2 and insomnia.