Numerous studies have shown that orexin knockout or neuronal ablation results in a narcolepsy-like phenotype (Hara et al., 2001; Adamantidis et al., 2007; Alexandre et al., 2013; Tabuchi et al., 2014), which is highly consistent with the pathological features of human narcolepsy, including excessive daytime sleepiness, hallucinations, and sudden collapse (Burgess and Scammell, 2012; Mahoney et al., 2019). This evidence concerns the gene HCRT and narcolepsy.