Kleine-Levin Syndrome

What happens during an episode

Episodes often start suddenly, sometimes after an infection, alcohol, lack of sleep or stress. Common features:

• Hypersomnia: sleeping 15 to 21 hours a day; when awake, the person is drowsy and slow.
• Cognitive changes: confusion, poor concentration, memory problems, slowed speech.
• Derealization: a strong feeling of being in a dream or that the world is unreal; one of the most characteristic symptoms.
• Apathy: lack of motivation and interest.
• Eating changes: overeating (megaphagia) in some, especially sweets; others eat less.
• Disinhibition: hypersexual behavior, childish behavior or irritability in some.
• Mood changes: anxiety, low mood, and occasionally hallucinations.

The person often has little memory of the episode afterward. Episodes may end with a brief period of insomnia or elevated mood.

Between episodes

People with KLS are usually completely normal between episodes. Some have mild, lasting memory or attention difficulties after many episodes.

Causes

The cause is unknown. Theories include problems in the hypothalamus and thalamus, which regulate sleep, appetite and behavior; autoimmune processes, since episodes often follow infections; and genetic susceptibility, as it occasionally runs in families and is more common in Ashkenazi Jewish people. Brain imaging during episodes can show reduced activity in specific regions, though routine MRI is normal.

Diagnosis

There is no specific test. Diagnosis is based on the pattern:

• at least 2 episodes of excessive sleepiness lasting 2 days to 5 weeks
• episodes recurring, usually more than once a year
• normal alertness, thinking and behavior between episodes
• at least one of: cognitive changes, derealization, eating changes, or disinhibition during episodes
• symptoms not explained by another condition

Tests rule out other causes:

• Brain MRI for tumors, strokes or inflammation.
• EEG for seizures; it may show nonspecific slowing during episodes.
• Blood and spinal fluid tests for infection, inflammation and metabolic causes.
• Sleep studies to exclude narcolepsy and idiopathic hypersomnia, which cause constant rather than episodic sleepiness.
• Psychiatric assessment, as bipolar disorder and depression can cause episodic hypersomnia.

Treatment

No treatment is consistently effective, so care focuses on safety and support:

• During episodes: let the person sleep safely at home with supervision, ensure food and fluids, avoid driving and risky activities, and avoid alcohol.
• Lithium: a mood stabilizer that has reduced the frequency and length of episodes in some studies. It needs regular blood monitoring.
• Stimulants may improve sleepiness during episodes but do not treat the confusion or other symptoms, and are not widely recommended.
• Avoid known triggers: infections where possible, alcohol and sleep deprivation.
• School and work support: documentation for absences, flexible deadlines and catch-up plans.
• Mental health support for anxiety and depression, which can follow episodes.

Outlook

Episodes usually become less frequent, shorter and milder over time, and KLS often resolves in a median of about 10 to 15 years. Most people return to normal life. Later onset, more frequent episodes, and male sex are associated with a longer course. Some people have mild lasting memory problems.

Frequently asked questions

What is Kleine-Levin syndrome?

Kleine-Levin syndrome is a rare sleep disorder that causes recurring episodes of extreme sleepiness, sometimes 20 hours a day, along with confusion, a dreamlike feeling, apathy and sometimes overeating or disinhibition. Between episodes, people are normal.

Why is it called Sleeping Beauty syndrome?

The nickname refers to the long periods of sleep during episodes, like the fairy tale character. The name can be misleading, though: episodes are distressing and involve confusion and behavior changes, not just peaceful sleep.

How long do Kleine-Levin syndrome episodes last?

Episodes usually last from a few days to several weeks, with a median of about 10 days. They often recur every few months. Over years, episodes typically become less frequent and less severe.

Does Kleine-Levin syndrome go away?

In most people, yes. KLS tends to resolve gradually, often within about 10 to 15 years of onset. Some people continue to have occasional episodes longer, and a minority have mild lasting memory or attention problems.