HCRT and narcolepsy: Deletion of both receptors produces a narcolepsy phenotype (Hondo et al., 2010; Kalogiannis et al., 2011) similar to that seen in the prepro-orexin knockouts (Chemelli et al., 1999; Mochizuki et al., 2004), with fragmented waking states, spontaneous sleep attacks and frequent cataplexy.