PURPOSE OF REVIEW: This article focuses on the clinical presentation, 
pathophysiology, diagnosis, differential diagnosis, and management of narcolepsy 
type 1 and narcolepsy type 2, idiopathic hypersomnia, Kleine-Levin syndrome, and 
other central disorders of hypersomnolence, as defined in the International 
Classification of Sleep Disorders, Third Edition (ICSD-3).
RECENT FINDINGS: In ICSD-3, the names of some central disorders of 
hypersomnolence have been changed: narcolepsy with cataplexy and narcolepsy 
without cataplexy have been renamed narcolepsy type 1 and narcolepsy type 2, 
respectively. A low level of hypocretin-1/orexin-A in the CSF is now 
theoretically sufficient to diagnose narcolepsy type 1, as it is a highly 
specific and sensitive biomarker. Conversely, other central hypersomnias are 
less well-defined disorders with variability in the phenotype, and few reliable 
biomarkers have been discovered so far. The epidemiologic observation that 
influenza A (H1N1) infection and vaccination are potential triggering factors of 
narcolepsy type 1 (discovered during the 2009 H1N1 pandemic) has increased 
interest in this rare disease, and progress is being made to better understand 
the process (highly suspected to be autoimmune) responsible for the destruction 
of hypocretin neurons. Treatment of narcolepsy remains largely symptomatic, 
usually initially with modafinil or armodafinil or with higher-potency 
stimulants such as methylphenidate or amphetamines. Several newer wake-promoting 
agents and psychostimulants have also been developed, including sodium oxybate, 
which has a role in the treatment of cataplexy and as an adjunctive 
wake-promoting agent, and pitolisant, a selective histamine H3 receptor inverse 
agonist that is currently only available in Europe.
SUMMARY: Although far less common than many other sleep disorders, central 
hypersomnias are among the most severe and disabling diseases in the field of 
sleep medicine, and their early recognition is of major importance for patients, 
especially children, to maximize their quality of life and functioning in 
activities of daily living.