CCR3 and sleep disorder: Shiftwork may negatively affect genes and factors involved in sleep disorders such that a SNP marker [44] and chemokine (C-C motif) receptor 3 (CCR3) susceptibility gene [45] associated with narcolepsy, MEIS1 locus, and neuronal nitric oxide synthase (NOS1) and BTBD9 associated with RLS [46–48].