Kleine-Levin syndrome (KLS) is a rare condition that causes a person to sleep for long periods of time. People diagnosed with KLS experience episodes where they sleep up to 20 hours per day and have changes to their behavior. The direct cause is unknown but treatment for KLS addresses symptoms. KLS usually resolves on its own over time.
Kleine-Levin syndrome (KLS), also known as “sleeping beauty syndrome” or “familial hibernation syndrome,” is an extremely rare condition that causes intermittent episodes where you sleep for long periods of time, which prevents you from staying awake during the day (hypersomnia). KLS also affects your behavior. People diagnosed with KLS often sleep for 16 to 20 hours per day during a KLS episode.
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Kleine-Levin syndrome can affect anyone. Men and people assigned male at birth are more likely to have the condition. Symptoms of the condition usually start in early adolescence, and episodes of sleepiness decrease in frequency and severity over a median course of 14 years.
Kleine-Levin syndrome is extremely rare. The estimated occurrence is 1 to 2 cases per million.
Symptoms usually begin in early adolescence and recur usually more than once per year. The average duration of KLS is 14 years. Symptoms include:
An episode occurs when you experience these symptoms for at least two days. KLS episodes can last for a few days, average around 10 days, or could last for a couple of weeks. One study suggests that people diagnosed with KLS have an average of 20 episodes during their lifetime.
Most people have trouble remembering what happens during an episode. They can wake up during an episode to eat or use the restroom but have limited physical function due to excessive sleepiness.
After you experience an episode, you’ll go back to your normal patterns of behavior and not have any symptoms of the condition except for possibly mild cases of memory loss.
Certain events trigger symptoms of KLS, including:
The cause of Kleine-Levin syndrome is unknown. Some studies suggest that an illness or injury causes damage to the part of your brain that regulates sleep (hypothalamus).
Most cases of KLS occur after having an illness similar to the flu or an infection. Research speculates that KLS could cause an autoimmune response where your body confuses healthy tissue with an invading organism, which causes symptoms.
Other research suggests that KLS could be genetic, related to mutations on genes LMOD3 and TRANK1.
Diagnosis of Kleine-Levin syndrome is challenging. There isn’t a specific test that can diagnose KLS. Healthcare providers diagnose KLS by eliminating other conditions with similar symptoms. They’ll begin your evaluation and work up after asking you about your symptoms, including how long you’ve had them and the severity.
Providers may offer tests including:
There isn’t a definitive treatment for KLS. In most cases, people with KLS don’t even take medication. During episodes, your healthcare provider can help you make accommodations — such as time off work or school — so you can sleep as much as your body needs. Other possible treatment options target symptoms of KLS. While some treatment options help keep you awake, one treatment doesn’t target all symptoms, especially symptoms that affect behavior and cognitive function. Treatment includes taking medicines like:
Your provider might suggest supportive therapy to work with a professional who can address changes to your behavior, hypersexuality, anxiety and depression.
There’s no single medicine to treat Kleine-Levin syndrome. Your provider will work closely with you to monitor your symptoms and how your body reacts to certain treatments, especially amphetamines, as there’s a high risk of dependency associated with the drug.
There isn’t a way to prevent Kleine-Levin syndrome because the cause is unknown. As the condition could relate to genetic changes, talk to your healthcare provider about genetic testing if you plan on becoming pregnant to understand your risk of passing genetic conditions onto your child.
People diagnosed with Kleine-Levin syndrome have a fair prognosis. Episodes usually decrease in severity and frequency over time. Most cases last for 10 to 20 years, with a median duration of 14 years. If you don’t have any episodes for six years, healthcare providers consider the condition cured.
After a Kleine-Levin syndrome diagnosis, talk to your healthcare provider about your best course of treatment and follow their instructions for the medication prescribed to you. In the event of an episode, stay at home in a safe environment. Postpone any activities during an episode like school or work. It’s unsafe to drive a car or operate heavy machinery because you could fall asleep behind the wheel and put yourself and others at risk. Surround yourself with a strong support system that’s aware of your condition and can help if you have an episode. It’s a good idea to wear a medical ID tag or put an emergency ID card in your wallet to notify others if you’re alone and have an episode.
KLS can affect your mental health. Reach out to your provider if you experience symptoms of anxiety or depression, feel helpless or have suicidal thoughts.
A note from Cleveland Clinic
Kleine-Levin syndrome (KLS) is an extremely rare condition that causes intermittent episodes where you sleep for long periods of time. The condition can take a toll on your mental and physical health. After your diagnosis, stay current with appointments to see your healthcare provider to make sure treatment is working and you don’t have side effects. Create a support system of your family and friends who can be there for you during or after an episode to help you get through each day safely.
Last reviewed by a Cleveland Clinic medical professional on 07/13/2022.
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Cleveland Clinic is a non-profit academic medical center. Advertising on our site helps support our mission. We do not endorse non-Cleveland Clinic products or services. Policy