HCRT and narcolepsy: Phenotypes of narcolepsy can be very diverse and include narcolepsy type 1 (NT1) with typical cataplexy that can present with decreased CSF levels of HCRT (in >90% of cases) or without any biological markers, and narcolepsy type 2 (NT2) without cataplexy but with some biological markers (such as sleep-onset REM periods).