Kleine-Levin Syndrome (KLS)
What is it?
A rare and complex neurological disorder that primarily affects adolescent males. It is characterized by recurring, yet reversible periods of excess sleep (up to 20 hrs. per day). Symptoms occur as episodes, typically lasting a few days to a few weeks. Episode onset is abrupt and the duration is unknown. Although affected individuals behave normally between episodes, they may not remember what occurred or what they did during an episode. It may be weeks or more between episodes. Symptoms may be due to malfunctioning of the hypothalamus and thalamus, parts of the brain that control appetite and sleep.

How common is it?
It is estimated that only 500-1,000 people in the world have KLS.

What are the causes?
The cause is unknown, however, there is some evidence that shows individuals with KLS may have been genetically predisposed to it. All diagnostic testing done on KLS patients have had normal results in regards to EEG, brain imaging, CSF examination, etc. There is a pattern of nearly half of KLS patients having flu-like symptoms prior to their first episode. Some researchers say that KLS may be an autoimmune disorder.

KLS Symptoms:
  1. Recurrent episodes of severe hypersomnia (2-31 days)
  2. One or more of the associated features
    • feeling of unreality, confusion, or hallucinations
    • irritability, aggression, odd behavior
    • binge eating
    • hyper sexuality
3. Interspersed with long periods of normal sleep, cognition, behavior, mood

What does an episode consist of?
  • excessive food intake
  • hypersomnia
  • irritability
  • childishness or "spacey"
  • disorientation
  • lethargy (lack of energy)
  • apathy (lack of emotions)
  • hallucinations
  • hypersensitive to noise and light
  • may result in depression

Is there a cure or treatment?
There is no definitive treatment, just suggestions including: watchful waiting at home rather than taking several medications. While stimulant pills may reduce sleepiness, they can cause irritability and do not improve cognitive abnormalities.

Long-term effects?
The frequency and intensity of the episodes an individual experiences slowly decreases between the ages of 8 and 12.

KLS Statistics:
  • 68-78% of cases are male
  • 81% of patients are adolescents
  • mean age of onset is 15 years old
  • first episode is triggered by an infection in 72% of patients
  • patients experience 7-19 episodes with a 10-13 day duration
  • relapses are usually every 3.5 months or so
  • EEG slowing is noticed during episodes of 70% of patients

Related Organizations:
  1. American Sleep Association
  2. Genetic and Rare Diseases Information Center
  3. Kleine-Levin Syndrome Foundation
  4. Mental Health America
  5. MUMS National Parent-to-Parent Network
  6. National Sleep Foundation
  7. National Institute of Mental Health
  8. National Institute of Neurological Disorders and Stroke

What research is being done on KLS?
NINDS supports various forms of clinical and basic research on diseases involving sleep disorders to better understand their onset and clarify their causes. The goal of the research is to discover exactly what the condition of KLS is and better ways to treat it. It is often difficult to perform research on KLS due to the randomness of the episodes and variances in individuals who suffer from it.