HCRT and narcolepsy: The clinical regulation of the orexin pathway has two-way therapeutic potential: orexin receptor agonists (such as TAK-994) improve the maintenance of arousal in narcolepsy by compensating for endogenous orexin deficiency (Mahoney et al., 2019), while antagonists (such as suvorexant) treat insomnia by blocking arousal signals (Herring et al., 2012).