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Kleine-Levin Syndrome: Symptoms, Causes, & Lifestyle Changes

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Written by Tim Becker, MD.
Resident Physician, The Mount Sinai Hospital
Last updated March 8, 2021

Kleine-levin syndrome quiz

Take a quiz to find out if you have kleine-levin syndrome.

Kleine-Levin syndrome (KLS) is a very rare sleep disorder characterized by persistent episodic hypersomnia and cognitive or mood changes.

Kleine-levin syndrome quiz

Take a quiz to find out if you have kleine-levin syndrome.

Take kleine-levin syndrome quiz

What is kleine-levin syndrome?

Kleine-Levin syndrome (KLS) is a rare neurological disorder characterized by episodes of excessive need for sleep that occur weeks or months apart. During episodes, sufferers often require more than 15 hours of sleep per day and experience other symptoms, such as irritability, confusion, and disinhibition.

Excessive sleepiness is the cardinal symptom of KLS. Other symptoms may occur but vary in severity across individuals. Symptoms are most severe at the beginning of an episode and gradually improve, before abruptly ending.

Treatments will likely involve lifestyle modifications to deal with episodes as well as medications to possibly alleviate some symptoms.

You should speak with your physician about these symptoms and potential treatment.

Kleine-levin syndrome quiz

Take a quiz to find out if you have kleine-levin syndrome.

Take kleine-levin syndrome quiz

Kleine-levin syndrome symptoms

KLS affects an estimated one in one million people, 70 percent of whom are men. Affected women typically experience a longer course of the disease. KLS most commonly starts during the teenage years, although it can occasionally occur in childhood or young adulthood. Fall and winter months are the most common time of onset, with 15 percent of cases starting in December.

Episodes may be as short as a few days or last for a few weeks. Between episodes, people with KLS typically live normal lives, with long periods of normal sleep patterns, stable mood, typical behavior, and clear thinking.

People who have had KLS episodes may experience stress about activities missed during the episode (such as needing to make up school or work) or anxiety about when another episode may occur. Episodes may occur every few weeks or may even be years apart. They usually become less severe as people get older, and often resolve entirely over eight to 12 years.

Main symptoms

Many people will not experience all the symptoms listed below:

  • Excessive sleep (hypersomnolence): During episodes of KLS, it's common to sleep most of the day (averaging approximately 18 hours), only waking for meals and to use the bathroom.
  • Excessive eating (hyperphagia): People experiencing KLS may consume any available food, even foods they may typically not eat, sometimes leading to weight gain after episodes.
  • Mood changes: While awake, it's typical to be irritable, seem to lack emotion entirely or seem to "not care" (apathy). These mood changes often improve rapidly when episodes of KLS end.
  • Childlike behaviors: Behavior while awake can seem odd for the person's age.
  • Confusion: The person may seem "spacey," with memory difficulties, and easily become disoriented to the time and location.
  • Perceptual disturbances: During episodes, people with KLS may experience hallucinations or feelings of losing touch with reality, feeling like they are living a dream.
  • Hypersensitivity: During episodes, noise and light may become particularly bothersome.
  • Difficulty sleeping (Insomnia): The end of an episode of KLS may be accompanied by a brief period of insomnia.

Other symptoms

Other symptoms that may occur in some people with KLS may include:

  • Impaired communication: Two-thirds of people experiencing KLS are observed to have communication disturbances, such as being too tired to communicate, having difficulty finding words, or having slurred speech.
  • Hypersexuality: Around 50 percent of people with KLS exhibit abnormally increased sex drive and may be observed engaging in disinhibited or inappropriate behaviors such as fondling oneself, lack of concern with body exposure, or unwanted sexual advances.

Kleine-levin syndrome causes

The underlying cause of KLS is not currently well understood but several hypotheses exist, including the following.

  • Brain dysfunction: Symptoms may result from dysfunction of the hypothalamus and thalamus — areas of the brain that control sleep, appetite, sexual behaviors, and body temperature. Abnormalities in the metabolism of the neurotransmitters serotonin and dopamine have also been identified as a possible contributing factor.
  • Viral infection: KLS is sometimes preceded by flu-like symptoms, such as fatigue, aches, and fever. Symptoms of infections precede up to 70 percent of cases of KLS.
  • Autoimmune: Sometimes the body's natural defenses against infection accidentally start attacking the body's own healthy tissues. These autoimmune attacks can be triggered by exposure to infections.
  • Head injury: It has been speculated that head injuries could initiate KLS.
  • Genetic predisposition: KLS has been found in some cases to run in families, suggesting that genetic factors may play a role in the development of the disorder.

Treatment options and prevention for kleine-levin syndrome

There is no definite cure for KLS, but some lifestyle modifications and supportive treatments can help reduce its negative impacts on life.

At-home treatments

You may consider establishing a plan when episodes seem to begin, as well as keeping an open line of communication with your school, any employers, and medical team. Rest and supportive care at home is the most advisable treatment, such as:

  • Activity restrictions: During the beginning of a KLS episode, excessive tiredness makes it nearly impossible to attend school or work.
  • Assistance with activities of daily living: During episodes, it may be difficult to care for oneself. Family and friends will need to help with meals, hygiene, and other tasks.


There is currently little high-quality evidence (in the form of randomized controlled trials) evaluating the effectiveness of medications for KLS. However, several medications are sometimes used in efforts to control the effects of the condition, including:

  • Stimulants: Medications such as modafinil, methylphenidate, or amphetamines can effectively reduce excessive daytime sleepiness, but are often not effective in severe episodes. Unfortunately, these medications also may increase irritability and seem to have minimal impact on cognitive and behavioral difficulties during episodes.
  • Mood stabilizers: Medications such as lithium and carbamazepine, typically used to treat bipolar disorder, may help prevent or shorten episodes.
  • Anti-epileptic medications: Some individuals have experienced improvement in symptoms while taking phenytoin, a medication used to treat seizures.

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Kleine-levin syndrome quiz

Take a quiz to find out if you have kleine-levin syndrome.

Take kleine-levin syndrome quiz

When to seek further consultation for kleine-levin syndrome

If you or your child experiences excessive sleepiness that interferes with work, school, or daily activities, you should consult your physician. Any persistent sleep disturbance that disrupts life should be reported to a physician. Several different sleep disorders exist, requiring a thorough evaluation. Your physician may suggest you undergo a sleep study or may refer you to a neurologist who specializes in sleep disorders for further evaluation.

If you or your child has been diagnosed with KLS

You should see your physician regularly since KLS is a cyclic disorder that often affects individuals for several years, often during an important period of life. It's important to inquire about all possible support for symptoms. Comprehensive treatment may require coordination between a variety of specialists, including a primary care physician, psychiatrist, neurologist, and psychologist, as well as coordination with schools.

Questions your doctor may ask to determine kleine-levin syndrome

  • Have you noticed any vision changes?
  • Is your fever constant or come-and-go?
  • Have you lost your appetite recently?
  • How long has your fever been going on?
  • How severe is your headache?

Self-diagnose with our free Buoy Assistant if you answer yes on any of these questions.

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The stories shared below are not written by Buoy employees. Buoy does not endorse any of the information in these stories. Whenever you have questions or concerns about a medical condition, you should always contact your doctor or a healthcare provider.
Dr. Rothschild has been a faculty member at Brigham and Women’s Hospital where he is an Associate Professor of Medicine at Harvard Medical School. He currently practices as a hospitalist at Newton Wellesley Hospital. In 1978, Dr. Rothschild received his MD at the Medical College of Wisconsin and trained in internal medicine followed by a fellowship in critical care medicine. He also received an MP...
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  1. Aran A, Mignot E, Arnulf I. Kleine-Levin syndrome (recurrent hypersomnia). UpToDate. Updated June 8, 2018. UpToDate Link
  2. Huang YS, Guilleminault C, Lin KL, Hwang FM, Liu FY, Kung YP. Relationship between Kleine-Levin syndrome and upper respiratory infection in Taiwan. Sleep. 2012;35(1):123-9. NCBI Link
  3. Kleine-Levin syndrome: Etiology, diagnosis, and treatment. Ann Indian Acad Neurol. 2010;13(4):241-6. NCBI Link
  4. Kleine-Levin syndrome. National Organization for Rare Disorders. NORD Link
  5. Billiard M, Podesta C. Recurrent hypersomnia following traumatic brain injury. SleepMed. 2013;14(5):462-5. PubMed Link
  6. Arnulf I, Rico TJ, Mignot E. Diagnosis, disease course, and management of patients with Kleine-Levin syndrome. The Lancet Neurology. 2012;11(10):918-928. PubMed Link