The strong correlation between narcolepsy and the human leukocyte antigens DRD2 or DQB1*0602 suggests that orexin neurons may be subjected to autoimmune destruction (Mignot, 2004; Fontana et al., 2010; Kornum et al., 2011; Singh et al., 2013; De la Herrán-Arita and García-García, 2014). Here, HCRT is linked to narcolepsy.