Kleine-Levin Syndrome (KLS) is a type of recurrent hypersomnia. People with KLS experience episodes of excessive sleeping that last between a few days and a few weeks. They may need to sleep as many as 20 hours a day. These episodes of needing extra sleep can occur multiple times in a year but eventually subside over time.
The disorder affects one to two people per million and primarily adolescent boys. Around 70% of people with KLS are male. KLS shares characteristics similar to narcolepsy and can cause excessive sleepiness and hunger.
The onset of KLS is sudden and may at first present like the flu. The primary symptom is excessive sleepiness that requires you to sleep for extremely long periods of time, often more than 18 hours in a day. There are a number of additional changes in cognition and behavior that accompany the need to excessively sleep:
These symptoms subside when the KLS episodes are over, and a person returns to their usual mood and demeanor. Some may experience continued memory loss.
The cause of KLS is currently unknown. Researchers have hypothesized multiple causes, including:
Researchers also hypothesize that KLS is tied to the hypothalamus and thalamus, which are parts of the brain that regulate sleep, hunger, and sexual behavior.
KLS is a sleep disorder that primarily affects teenagers. Boys are four times more likely to have the disorder than girls. Eighty-one percent of reported cases start in the second decade of life. People with KLS rarely experience their first episode after age 30.
Genetics may also play a factor. Around 5% of cases of KLS occur within families. Additionally, KLS is slightly more prevalent in the Ashkenazi Jewish population.
A number of events associated with KLS have been documented. These include:
Often, KLS is first misdiagnosed as another type of sleep disorder, such as excessive sleepiness or narcolepsy. However, KLS differs from other sleep disorders. Patients with KLS do not experience sleep paralysis, cataplexy, or sleep-disordered breathing.
Because patients with KLS present with symptoms of depression or anxiety, they might also be initially diagnosed with a psychiatric illness. However, the depressive symptoms from KLS disappear once the episodes are over.
Typically, healthcare providers first rule out other disorders that have similar symptoms. Healthcare providers also verify that drugs or medications are not causing the symptoms.
To be diagnosed with KLS, a person must meet first the criteria for recurrent hypersomnia:
Other causes for hypersomnia must be ruled out. Then, in addition to hypersomnia, a person has to experience a minimum of one of the following:
Sleep studies can verify the amount of time spent sleeping. Sleep tests can also measure electrical activity in the brain. In cases of KLS, brain activity slows down as much as 70% during sleep. Brain scans typically present as normal. Some physicians may test memory, and patients with KLS usually perform poorly.
Treatments for KLS are not consistently effective. Supportive care at home, especially from parents or guardians, can help ensure a safe environment during episodes of KLS. Medications are recommended only as a secondary treatment. Some medications can reduce certain symptoms rather than eliminate KLS.
Patient support is crucial to overall wellbeing. Caregivers can:
Medications do not completely prevent future episodes of KLS. Limited research suggests that lithium can reduce the number of episodes, but cannot eliminate them.
Some drugs may improve some symptoms of KLS but negatively impact others. For example, amphetamines and modafinil can treat sleepiness but worsen irritability. Temporary use of antidepressants or mood-stabilizing drugs may alleviate psychiatric symptoms. Antidepressants prevented relapse in only one known case.
If you experience symptoms of KLS, report them to your healthcare provider as early as possible. After an episode, some patients may feel embarrassed about their behavior or actions and be reluctant to share their symptoms. However, a clear understanding of your symptoms can help your doctor confirm diagnosis and develop an appropriate treatment plan.
Over time, KLS episodes typically reduce in frequency and severity. Oftentimes the episodes will spontaneously resolve. Those who have not experienced a KLS episode after six years are considered cured.