PMCH and narcolepsy: Given that the symptoms of narcolepsy either relate to excessive sleepiness, or an intrusion of REM sleep phenomena into wakefulness—and that MCH can have a REM sleep-promoting effect—it is reasonable to ask whether the MCH system could play a role in narcolepsy symptomatology, and/or whether agents targeting MCHR1 could prove useful therapeutics for patients with narcolepsy.