Kleine-Levin Syndrome

Last updated on

What is Kleine-Levin Syndrome?

Hunger, fixation on sex, and sleeping in are normal among teenage boys. But when these behaviors are extreme, it may be the Kleine-Levin Syndrome (KLS), or what some have dubbed “the Sleeping Beauty syndrome.”

The KLS is a rare neurological and sleep disorder in the hypersomnia family that mainly affects teenage boys.Like other hypersomnias including narcolepsy, Kleine-Levin syndrome involves excessive daytime sleepiness.

How common is Kleine-Levin syndrome?

TThis condition is rare, affecting fewer than 200,000 patients in the U.S. The median age of onset is 15.  About 70 percent of those with the disorder are adolescent males.

Symptoms of Kleine-Levin syndrome include excessive daytime sleepiness and sleeping for long stretches (patients sometimes wake only to eat and use the bathroom), sometimes accompanied by increased appetite and hypersexuality, for a period of 2 to 31 days. These periods are called “episodes”. During an episode, patients may also experience confusion, disorientation, and hallucinations.

On average, patients experience 7 to 19 episodes lasting 10 to 13 days each, and relapse every 3.5 months. In between episodes, symptoms disappear. Relapses can occur for up to a decade before the illness spontaneously resolves. The sudden onset of each episode can be accompanied or triggered by flu-like symptoms or infections (38.2%), head trauma (9%), alcohol consumption (5.4%), or sleep deprivation.

What causes Kleine-Levin Syndrome?

The cause of Kleine-Levin syndrome is unknown, although the disorder has a strong genetic component. This uncommon sleep disorder tends to run in families, especially of Jewish ancestry. About 15 percent of the Kleine-Levin syndrome patients are of Jewish origin and “the incidence reported in Israel is unproportionately high,” according to a paper in a Jewish medical journal.

“The most promising findings are the familial clustering and a potential Jewish founder effect, supporting a role for genetic susceptibility factors,” according to French researchers.


Practitioners use a comprehensive medical history to make a diagnosis of KLS. Because brain imaging does not show any abnormalities in Kleine-Levin syndrome patients, the criteria for diagnosis are clinical, relying on patients’ and families’ descriptions of abnormal behavior.


This disorder generally appears in adolescence and subsides on its own. Over time, episodes diminish in frequency and severity, becoming less disruptive to the individual and family. On average, it takes 8-14 years for patients to “outgrow” Kleine-Levin syndrome, with longer duration in men, in patients with hypersexuality, and when onset is after age 20.

Some medications that promote wakefulness can help correct sleep abnormalities and excessive sleepiness present in Kleine-Levin syndrome. Amphetamines and lithium have been used successfully in some patients. Amphetamines helped decrease the oversleeping in 40% of patients. According to the same review in the journal Brain, “lithium had a higher reported response rate (41%) for stopping relapses when compared to medical abstention (19%).”

Outside of these attempts to mitigate the symptoms, patients and their families are usually told to inform themselves, connect with others experiencing the same syndrome, and wait the disease out.

Additional Kleine-Levin Resources


Popular Reads
Stages of Sleep and Sleep Cycles

Usually sleepers pass through five stages: 1, 2, 3, 4 ...

Mattress Reviews and Comparisons 2018 – Complete Mattress Database

The research team at Tuck has put together the most ...

Parent’s Guide to Healthy Sleep

Every child needs good sleep for healthy development, growth, and ...