Kleine–Levin syndrome

Overview

Kleine–Levin syndrome (KLS) is a rare neurological disorder characterized by recurring episodes of excessive sleep (hypersomnia), altered behavior, and cognitive disturbances. Also referred to as “sleeping beauty syndrome,” KLS most commonly affects adolescent males but can also occur in females and younger or older individuals. Episodes can last from days to weeks, during which the affected person may sleep up to 18–20 hours per day and experience profound behavioral and psychological changes. Between episodes, individuals usually return to their normal baseline health.

Causes

The exact cause of Kleine–Levin syndrome remains unknown, but it is thought to involve dysfunction in the hypothalamus and thalamus—areas of the brain that regulate sleep, appetite, and behavior. Potential triggers and contributing factors may include:

• Infections (such as viral illnesses)

• Autoimmune dysfunction

• Head trauma

• Genetic predisposition (though no specific gene has been identified)

Some cases of KLS appear to follow flu-like illnesses, suggesting an inflammatory or immune-related process may be involved.

Symptoms

Symptoms of KLS occur in episodic cycles, with each episode typically lasting from several days to a few weeks. Common features include:

• Hypersomnia: Sleeping up to 18–20 hours per day, with only brief periods of wakefulness

• Hyperphagia: Compulsive overeating during episodes

• Derealization: Feelings of detachment or being in a dream-like state

• Behavioral changes: Irritability, aggression, apathy, or childish behavior

• Cognitive disturbances: Confusion, poor concentration, memory issues

• Hypersexuality: Inappropriate sexual behavior or increased sexual urges (in some cases)

Between episodes, individuals usually recover completely, although some may experience lingering cognitive symptoms over time.

Diagnosis

Diagnosing Kleine–Levin syndrome is primarily clinical and involves ruling out other conditions. There are no definitive tests for KLS. Key steps include:

• Detailed clinical history documenting the pattern and duration of hypersomnia episodes

• Exclusion of other causes of excessive sleep, such as narcolepsy, depression, encephalitis, epilepsy, or metabolic disorders

• Brain imaging (MRI) and EEG to rule out structural or electrical abnormalities

• Sleep studies to evaluate sleep architecture (usually normal between episodes)

• Neuropsychological evaluation during and after episodes

Diagnosis is often delayed due to the rarity and unfamiliarity of the condition among healthcare providers.

Treatment

There is no specific cure for Kleine–Levin syndrome, and treatment is largely supportive. Management strategies focus on minimizing the severity of episodes and improving quality of life. These may include:

• Supportive care: Ensuring safety during episodes, maintaining hydration and nutrition, and providing supervision

• Medications:

  • Stimulants: Such as modafinil or amphetamines to reduce sleep duration during episodes (limited efficacy)

  • Mood stabilizers: Like lithium or carbamazepine, which have shown benefit in reducing episode frequency and severity in some patients

  • Antidepressants or antipsychotics: May be tried for associated mood or behavioral symptoms, though evidence is limited

• Psychological support: Counseling and education for patients and families to manage the psychological impact

Prognosis

The long-term prognosis of Kleine–Levin syndrome is generally favorable. Most individuals experience a gradual decrease in episode frequency and severity over time, with spontaneous remission often occurring after 8–12 years. However, the condition can significantly disrupt education, work, and social life during its active phase. Early recognition, supportive care, and regular follow-up can help reduce the impact of the disorder and improve outcomes. Cognitive and emotional support is important for maintaining quality of life.