Glossary

Kleine-Levin syndrome [KLS]

Kleine-Levin syndrome (KLS) is a rare hypersomnia sleep disorder of the brain (neurologic disorder). It affects the brain’s ability to control sleep, wakefulness, thinking, and behaviors. KLS causes repeated episodes (periods) of very long sleep (often 16 to 20 hours a day) and excessive daytime sleepiness (EDS).

Episodes may last for days or weeks at a time. During episodes, people who have KLS have other symptoms, such as:

• Being slow in thinking and speaking
• Having memory loss
• Being exhausted and bedridden, with no motivation for talking, eating, or seeing people (major apathy)
• Feeling that things are unreal (derealization)
• Eating much more than they normally do
• Doing things they wouldn’t usually do

These symptoms usually go away between episodes. Read more on our KLS web page.