Central Disorders of Hypersomnolence

Kleine-Levin Syndrome


Kleine-Levin syndrome (KLS) is a sleep disorder that includes waxing and waning episodes of severe sleepiness during which a person has difficulty with thinking, behavior, and psychiatric issues. These episodes also include very long sleep—up to 16 to 20 hours per day. KLS usually occurs for the first time after an infection or alcohol use during the teenaged years and is twice as common in males as in females.


KLS is a very rare condition, affecting 1 or 2 of every 1 million people.


Five criteria must be met to make a diagnosis of KLS.5

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