Klein-Levin syndrome (KLS) or “sleeping beauty” is a disease called “human hibernation disease”. It is considered a rare neurological-psychiatric disorder. It usually appears intense at the age of 12-25 years. It is more common in adolescence and male individuals. 70% of the patients are adolescent males. It is sometimes seen in adults and children.

Klein-Levin syndrome (KLS)

Klein-Levin syndrome (KLS) or “sleeping beauty” is a disease called “human hibernation disease”. It is considered a rare neurological-psychiatric disorder. It usually appears intense at the age of 12-25 years. It is more common in adolescence and male individuals. 70% of the patients are adolescent males. It is sometimes seen in adults and children.

The exact cause of Klein-Levin Syndrome is unknown. However, estimations are made on many reasons. Generally, abnormal values are not detected in the biochemistry, hemogram and hormone tests of the patients.



In this disease, attacks occur at least twice a year, and these sleep attacks can last from two days to four weeks. These sleep attacks pass suddenly and the patient is quite normal during periods without sleep attacks. During the attack period, the patient sleeps for about twenty hours a day. The patient performs other physiological needs during sleep unconsciously or semi-consciously and goes back to sleep. Despite the length of the sleep period, the patient shows excessive sexual and overeating urges during his waking hours. In addition, mental disorder (confusion), forgetfulness (amnesia), irritability (aggression), lack of attention, disproportionate and age-incompatible behavior disorders (compulsive or mood disorders), disorder in the perception of time and space (disorientation) are frequently observed.

Signs and Symptoms of Klein-Levin Syndrome

The causes and symptoms of the disease vary according to the patient. In some patients, no cause can be found. Generally, in the attacks of people with the disease:

  • Excessive sleepiness and desire to sleep (hypersomnia), not getting out of bed up to 21 hours a day,
  • Excessive sexual desire (hypersexuality), masturbation and sex fantasies,
  • Mental disorder (confusion), inability to understand, sleepiness,
  • Forgetfulness (amnesia), short-term memory impairment,
  • Overeating (hyperphagia), inability to control eating,
  • Irritability (aggression), overreaction (irritability), or abnormal apathy to the environment (apathy).
  • Attention deficit, disproportionate and age-appropriate behavioral disorders (compulsive or mood disorders),
  • A specific feeling of derealization (a dream-like state in which perception changes),
  • Disorientation in the perception of time and space is frequently observed.

Although not as much as the symptoms listed above, the following symptoms may also appear:

  • Childish behavior, crying and shouting crises,
  • Depersonalization (the state of being alienated from all or part of the person’s body in a different perception),
  • Abnormal behavior characterized by aggression, anger disorders, irritability,
  • Speech and self-expression disorders, decreased desire to speak,
  • Depressed mood, recurrent episodes of depression, anger towards life, embarrassment,
  • Hallucinations and nightmares, fear of unknown origin,
  • Anxiety disorder (anxiety), restlessness.

Sometimes, some patients may not experience any or some of these symptoms. It is thought that the disease may cause other complications as well.

Disease-Associated Genes, Causative Factors and Risk Factors

These patients were analyzed to have HLA-DR2 and DQ1 antigens and share haplotype, and carry HLA-DQB1, tryptophan hydroxylase (TpH) and catechol-O-methyltransferase (COMT) gene polymorphisms. These findings suggest an autoimmune cause for Kleine-Levin syndrome.

Diagnosing Klein-Levin Syndrome

For Kleine-Levin syndrome (KLS), patient history and observations are reviewed. Structural brain imaging, cerebrospinal fluid, biochemistry and hemogram (complete blood count) tests and serological inflammatory tests are not indicative.



Epileptic activity is rare. EEG slowing is mostly observed in patients during the attack period. Functional brain imaging shows decreased blood supply and hypometabolism in the thalamus, hypothalamus, and frontotemporal areas. It has been reported that some patients have hypodense lesions on brain tomography (CT) examination.

In SPECT studies, decreased blood supply can be detected in the right and left frontal lobes, temporal lobe, left hypothalamus, right parietal lobe, bilateral thalamide, basal ganglia, bilateral medial, dorsolateral frontal regions, mesiotemporal region, and left temporal lobes of the patients.

Treatment of Klein-Levin Syndrome

There is no definitive treatment for Kleine-Levin syndrome. In these patients, symptomatic treatment is applied. According to the symptoms, drug treatments are applied. Also, lithium treatment is applied because it reduces the frequency of attacks or stops the attacks and provides a success rate of 37-46%.

Prognosis of Klein-Levin Syndrome

This disease can last from 8 to 14 years at intervals. It may become silent at times and recur suddenly. The prognosis is generally good. Most patients show less frequent and less severe attacks with advancing age and the disappearance of the syndrome around 30-35 years of age. During asymptomatic periods, approximately 30% of patients have mild difficulty concentrating or remembering. Persistent psychiatric disorders are seen in a minority of patients.


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