Central Disorders of Hypersomnolence
(Narcolepsy, Hypersomnia and more)

The central disorders of hypersomnolence (inability to stay awake) are a group of disorders that result in pathologic daytime sleepiness (hypersomnia), which manifests as either an irrepressible need to sleep or episodes of daytime sleep.⁷

These disorders include: Narcolepsy type 1 and 2, idiopathic hypersomnia, Kleine-Levin syndrome, insufficient sleep syndrome, hypersomnia due to a medical or neurologic disorder and hypersomnia due to a medication or substance.⁷ For the latter four conditions, the sleepiness and associated symptoms are manifestations of the hypersomnia and not the consequence or comorbidity of the condition or medication/substance.⁷ Diagnosis generally requires a combination of clinical evaluation, exclusion of other disorders, and objective testing within the sleep laboratory, although Kleine-Levin syndrome can be diagnosed based on clinical features alone.

Narcolepsy

Kleine-Levin Syndrome

Kleine-Levin Syndrome, unlike the other disorders of hypersomnolence, is episodic, typically lasting 2 days to 5 weeks, rather than persistent.⁷ People with Kleine-Levin Syndrome experience recurrent attacks of profound sleepiness and long-sleep time, during which they will sleep an average of 18 hours/day ¹¹, as well as at least one of the following during the attacks: altered perception, cognitive dysfunction, disinhibited behavior or disordered eating patterns.⁷ At least two separate attacks, with normal baseline in between, must occur for a Kleine-Levin syndrome diagnosis.⁷

Treatment

Various pharmacological and non-pharmacological treatment options are available for the disorders of hypersomnolence, and your sleep physician will discuss and determine what is best for you following your diagnosis.

Symptoms of narcolepsy type 1 include: hypersomnia, cataplexy (a sudden loss of muscle tone induced by emotion - most commonly strong positive emotions such as laughter), sleep paralysis (the person is awake but unable to remove any voluntary muscles other than the eyes), sleep-related hallucinations (hallucinations upon falling asleep or waking up), and disrupted nocturnal sleep. Many patients will not have all 5 symptoms.⁷

The presence of cataplexy is the clinical feature that differentiates between narcolepsy type 1 and 2. Cataplexy is not observed in the other disorders of hypersomnolence.

No clinical features are unique to narcolepsy type 2.⁷