als with hypersomnolence disorder have symptoms  of depression that may meet criteria for
a depressive disorder. This presentation may be  related to the psycho social consequences of
persistent increased sleep need. Individuals with hypersomnolence disorder are also at
risk for substance-related disord ers, particularly related to self-medication with stimulants.
This general lack of specificity may contribu te to very heterogeneous profiles among indi-
viduals whose symptoms meet the same diagnostic criteria for hypersomnolence disorder.
Neurodegenerative conditions, such as Alzhei mer’s disease, Parkinson’s disease, and mul-
tiple system atrophy, may also be associated with hypersomnolence. 
Relationship to Internat ional Classification of 
Sleep Disorders
The International Classification of Sleep Disorders,  2nd Edition (ICSD-2), differentiates nine
subtypes of “hypersomnias of central origin ,” including recurrent  hypersomnia (Kleine-
Levin syndrome).
Narcolepsy
Diagnostic Criteria
A. Recurrent periods of an irrepressible need to sleep, lapsing into sleep, or napping oc-
curring within the same day. These must have been occurring at least three times per
week over the past 3 months. 
B. The presence of at least one of the following:
1. Episodes of cataplexy, defined as either (a) or (b), occurring at least a few times
per month: 
a. In individuals with long-standing disease, brief (seconds to minutes) episodes
of sudden bilateral loss of muscle tone with maintained consciousness that are
precipitated by laughter or joking.