Kleine-Levin syndrome is a rare disorder characterized by the need for excessive amounts of sleep (hypersomnolence), (i.e., up to 20 hours a day); excessive food intake (compulsive hyperphagia); and behavioral changes such as an abnormally uninhibited sexual drive. The disorder primarily affects adolescent males. When awake, affected individuals may exhibit irritability, lack of energy (lethargy), and/or lack of emotions (apathy). They may also appear confused (disoriented) and experience hallucinations. Symptoms of Kleine-Levin syndrome are cyclical. An affected individual may go for weeks or months without experiencing symptoms. When present, symptoms may persist for days to weeks. In some cases, the symptoms associated with Kleine-Levin syndrome eventually disappear with advancing age. However, episodes may recur later during life.

The exact cause of Kleine-Levin syndrome is not known. However, researchers believe that in some cases, hereditary factors may cause some individuals to have a genetic predisposition to developing the disorder. It is thought that symptoms of Kleine-Levin syndrome may be related to malfunction of the portion of the brain that helps to regulate functions such as sleep, appetite, and body temperature (hypothalamus). Some researchers speculate that Kleine-Levin syndrome may be an autoimmune disorder.

People living with KLS may not experience symptoms every day. In fact, affected individuals typically don’t have any symptoms between episodes. When symptoms do appear, they can last a few days, weeks, or even months.

Common symptoms include extreme sleepiness. There may be a strong desire to go to bed and trouble getting up in the morning.

During an episode, it’s not uncommon to sleep up to 20 hours a day. People living with KLS may get up to use the bathroom and eat, then go back to sleep.

Fatigue can be so severe that people with KLS are bedridden until an episode passes. This takes time and energy away from family, friends, and personal obligations.

Episodes can also trigger other symptoms, such as:

• hallucinations
• disorientation
• irritability
• childish behavior
• increased appetite
• excessive sex drive

This may result from reduced blood flow to parts of the brain during an episode.

KLS is an unpredictable condition. Episodes can recur suddenly and without warning weeks, months, or years later.

Most people resume normal activity after an episode without any behavioral or physical dysfunction. However, they may have little memory of what happened during their episode.

The exact cause of KLS is unknown, but some doctors believe certain factors can increase your risk for this condition.

The treatment of Kleine-Levin syndrome is directed toward the specific symptoms that are apparent in each individual. Treatment may require the coordinated efforts of a team of specialists. Pediatricians, psychiatrists, psychologists, neurologists, and other health care professionals may need to systematically and comprehensively plan an affected adolescent's treatment.

Specific therapies for the treatment of Kleine-Levin syndrome are symptomatic and supportive. In some cases, stimulants may provide temporary relief from the need for excessive amounts of sleep. Amphetamines were most successful in reducing sleepiness in affected individuals, but had no effect on other associated symptoms (e.g., behavioral changes).

KLS may arise from an injury in the hypothalamus, the part of the brain that controls sleep, appetite, and body temperature. A possible injury could be falling and hitting your head, although more research is needed to confirm this link.

Some people develop KLS after an infection like the flu. This has led some researchers to believe KLS may be a type of autoimmune disorder. An autoimmune disease is when the body’s immune system attacks its own healthy tissue.

Some incidents of KLS may also be genetic. There are cases where the disorder affects more than one person in a family.