What is kleine-levin syndrome?

Kleine-Levin Syndrome (KLS) is a sleep disorder which causes recurring episodes of extreme sleepiness, sometimes up to 20 hours a day (hypersomnia), lasting days or even weeks. These episodes come and go unpredictably.¹

Symptoms include:

• Excessive sleep during episodes
• Mood changes: irritability, confusion, anxiety, and depression
• Hallucinations
• Increased appetite (hyperphagia)
• Increased sex drive (hypersexuality)
• Struggling to stay awake and feeling very tired outside of episodes

Epidemiology

• Population: A Rare condition that affects around 5 in every 1 million people²
• Age: Mostly affects boys during adolescence, especially around age 15-16²
• Gender: More common in males, 2:1 ratio²
• Higher prevalence in people of Jewish descent³ 

Aetiology

The exact cause of KLS is not clear or known.

Psychological theories have been ruled out as they do not match the full picture in terms of the features of KLS.⁴

Brain-related factors - like epilepsy or brain infections have been considered, but tests such as electroencephalography (EEGs, brain wave tests) of KLS patients do not fully support these links, though unusual brain wave activity is often seen, changes in deep sleep and REM sleep during attacks.⁴ EEG tests are especially helpful because they can pick up on slowed brain activity during an episode in about 70% of cases.¹⁰

Sleep and brain chemicals - particularly orexin (important for staying awake), might play a role, but findings are mixed as orexin levels are low but not as low in people with narcolepsy.⁴

Quality of life between episodes

KLS can greatly impact a person’s quality of life. During episodes, individuals sleep excessively, sometimes for days, weeks, or even months, which makes it harder to maintain a daily routine or engage in everyday activities. Although sleep is essential, sleeping too much can have negative effects. 

• 75% have hyperphagia, eating 6 to 8 meals a day
• 50% report depression-like moods during episodes
• 15% experienced suicidal thoughts
• 50% show signs of hypersexuality, most often in men²

These drastic behavioural, emotional, and cognitive changes can severely affect mental health and overall well-being.

Impact on education and employment 

KLS can disrupt both education and employment due to the long and repeated sleep episodes. Students may miss significant amounts of school, making it hard to keep up with their peers. This is especially concerning during adolescence, a crucial time for learning, development, and forming long-term goals. 

During adolescence, the brain becomes more efficient. Teenagers begin to understand complex ideas, think more deeply, reflect on themselves and their thoughts (metacognition), and start planning for their future. It is a key stage for forming academic and personal goals. However, for young people with KLS, these long sleep episodes and low energy in between can mean missing out on this important developmental phase. The same issue affects working adults. Long sleep episodes can interfere with job performance, reliability, and the ability to maintain employment. Many workplaces are not equipped to accommodate someone with unpredictable long absences. Behavioural symptoms like mood swings, anxiety, depression, and poor concentration can also make it difficult to perform well at work. However, some employers may offer accommodations, like flexible hours, remote work options, or extended leave to help manage the condition. While this is not common everywhere, it shows progress in understanding and supporting KLS in the workplace.⁶ 

Cognitive function

Researchers studied 122 people with KLS outside of their sleep episodes and compared them with 42 healthy individuals. They found that KLS patients had:

• Slower thinking speed
• Difficulty with problem-solving and attention
• Memory issues, especially recalling information

The more frequent and intense the episodes were, the worse the memory problems. A follow-up 1.7 years later showed that attention and reasoning slightly improved, but thinking speed remained low and memory recall worsened. These ongoing cognitive difficulties make learning and academic examinations harder for KLS students. That is why researchers suggest that students with KLS should get regular cognitive assessments so schools can give them the support they need.⁵ 

Struggles with relationships 

Managing relationships while living with KLS can be challenging. Behavioural and emotional symptoms like irritability, mood swings, lack of energy, or lack of emotions can make it hard to form or maintain close connections with others, whether romantic, family, or friends.

Excessive sleepiness also leads to physical and mental exhaustion, often leaving people with little motivation to socialise or be in a relationship. This can cause feelings of isolation and frustration. Symptoms like hyperphagia or hypersexuality can also place a strain on relationships. Still, while difficult, having a healthy relationship with KLS is possible with understanding, good communication, and support.

Social isolation and stigma

Many people with KLS face misunderstanding from others. Friends, family or colleagues may not fully believe or grasp the nature of the disorder, which can often lead to confusion, a lack of mutual support, or even lead to judgment. Due to KLS being rare and misunderstood, people living with it may be unfairly seen as lazy or unreliable. This stigma can cause feelings of shame and social withdrawal, meaning that seeking support becomes less likely. A lack of awareness often results in harmful misconceptions, making it even harder for those affected to feel understood.

Managing daily life between episodes

There is currently no cure for KLS, and since its cause is still unknown, managing it can be challenging. However, there are ways to improve the quality of life between episodes.

Medical treatment

NOTE: Medication should only be taken under medical supervision

Because KLS is rare and unpredictable, treatment options are limited and do not always work for everyone. Stimulants like amphetamines or modafinil are sometimes used to help reduce the feeling during episodes. While they can help with being more alert, they do not improve mood, memory, or other symptoms, and they tend to work better when symptoms have already started to ease.^{8, 9}

Case study 1

A 33-year-old woman with KLS experienced severe sleepiness, hyperphagia, and memory issues. She slept for over 16 hours a day, only waking up to eat, and struggled with energy and mood when she was awake. Excessive eating was a major problem for her, and she ended up being referred to an addiction treatment centre. Antidepressants did not help, but a combination of modafinil and lithium eventually helped stop the symptoms and episodes completely. When she stopped taking these, her symptoms returned, but once she resumed, she remained episode-free for five years. Her study highlights the importance of early diagnosis, which unfortunately took 3 years in her case.¹⁰ 

Case study 2

A 23-year-old woman with KLS began having episodes after a viral illness. She would sleep for over 20 hours a day for two weeks at a time, and she experienced hyperphagia and hypersexuality. She used a mix of medications, including lithium, modafinil, and later, a transdermal flumazenil (a GABA-A receptor/benzodiazepine antagonist), which helped reduce her episode frequency. Eventually, she was able to stop most medications and remain functional, finishing her master’s degree and holding a job.¹²

On the other hand, not all medications work for everyone. Research stated that certain stimulants may increase irritability and often do not help with behavioural or memory issues. Modadinil may shorten how long episodes last, but not how often they occur. Lithium has helped some KLS patients, but it is not that effective ¹¹ 

Therapeutic and support

Psychological support, like therapy or occupational therapy, can help with emotional regulation, cognitive challenges, and daily functioning between episodes.² 

Support at school and work 

Having open and honest communication is crucial when it comes to getting the right support, especially in schools or the workplace. For people living with KLS, it is important for them to explain their condition to employers: what it is, how it affects them mentally, emotionally, and cognitively. This helps others understand the challenges they face and why certain accommodations might be necessary. These might include flexible working hours, remote work to avoid commuting (especially since episodes can happen randomly), and adjusting tasks when fatigue or cognitive difficulties set in.

For students with KLS, they have the same right to education as anyone else; the same goes for any other disability or condition. However, they may need specific accommodations to help them keep up and participate in school like their peers. Clear communication with teachers, school nurses, and administrators is key to making sure they get the right kind of support. Since episodes can prevent them from attending school, they may miss important lessons or exams, which can affect their academic progress. Tools like Individual Educational Plans (IEPs) or Personal Learning Plans (PLPs) can be really helpful in identifying their needs and ensuring they receive consistent support to help them succeed in school academically.¹³ 

Summary

• KLS is more than just excessive sleep; it deeply impacts a person’s identity, mental health, ability to function, and overall quality of life during episodes
• Because it is a rare and poorly understood condition, getting a proper diagnosis often takes years, and finding the right treatment can be challenging
• Increased research and awareness are key to developing better support systems and strategies, helping people with KLS lead more fulfilling, manageable lives