KLS Support UK - Helping families affected by Kleine-Levin Syndrome

What is Kleine-Levin Syndrome (KLS)?

KLS is a rare disorder characterised by recurrent bouts of excessive sleep associated with reduced understanding of the world and altered behaviour. KLS usually starts in the teenage years but can occur in younger children and adults. Each episode lasts days, weeks or months during which time all normal daily activities stop. Individuals are not able to care for themselves or attend school and work. People with KLS coming out of episodes will have little or no memory of what happened during an episode. Between episodes they have normal sleep, understanding and behaviour. KLS episodes may continue for 10 years or more. KLS is sometimes referred to in the media as “Sleeping Beauty” syndrome.

What are the symptoms of KLS?

Symptoms vary between individuals with KLS but the following first 3 symptoms are always present during a bout:

Hypersomnia (Excessive prolonged sleep)

Someone with KLS will “sleep” 15 to 22 hours for days, weeks or even months. They feel and look exhausted. Sleep may be disturbed.

Cognitive impairment

They experience confusion, reduced understanding and feel in a dreamlike state (derealisation). They cannot concentrate, have difficulty communicating, speaking and reading and do not remember events after an episode.

Altered behaviour

Their demeanour is altered so that they appear spaced out or childlike. They are affected by apathy, are uncommunicative and may engage in automatic and repetitive behaviour. Teenagers will stop normal activities such as using mobile phones, seeing friends and showering and may listen to the same music or watch the same programme repeatedly.

Some individuals with KLS have:

Compulsive Eating (known medically as Hyperphagia)

Sometimes those with KLS eat compulsively and mechanically during a bout and have food cravings for sweets, snacks or foods they would not normally eat. Some eat less.

Other symptoms

Some individuals, generally boys, experience hypersexuality or other disinhibited behaviour. Some experience migraine headaches with hypersensitivity to noise and light. If they are not in their home environment then some may become anxious, aggressive or irritable particularly if prevented from sleeping. Some have autonomic symptoms including disturbed body temperature control, and altered blood pressure and heart rate. Some may have hallucinations and delusions in some bouts. Towards the end of an episode some get depressed and some experience elation and insomnia for 1 to 3 days afterwards.

What causes KLS?

The cause of KLS is not known. An episode of KLS is often triggered by an infection or sometimes by head injury, alcohol intake or sleep deprivation. Researchers are looking into genetic, auto-immune, inflammatory or metabolic involvement. Contact with KLS individuals cannot pass on the condition.

Who gets KLS?

KLS is extremely rare, estimated at 1-2 cases per million people. KLS usually starts in adolescence but can occur in younger children and adults. KLS affects boys more than girls.


The diagnosis of KLS is often missed because it is rare and there is lack of awareness. For some it has taken years before the correct diagnosis was made. It is important for the person with KLS and their family to have a diagnosis.

There are no tests for KLS. Diagnosis is based on a clinical interview with the patient and their family and exclusion of other similar conditions. As the person with KLS has little or no memory of an episode it is important for the parents to be present at medical consultations. Parents will usually describe a teenager who is different from before. Questions about sleep, food, personal hygiene, use of mobile phones and socialising with friends are therefore important.

Before a diagnosis of KLS is reached it is important to rule out other causes such as narcolepsy, encephalitis, tumours, drugs, migraine and psychological disorders. Sometimes investigations such as EEG, sleep studies, memory studies, MRI, CT and SPECT scans and blood tests will be carried out.

Diagnostic criteria for Kleine-Levin syndrome

The following KLS definition was developed by the International Classification of Sleep Disorders - Third Edition (ICSD-3, 2014)

Criteria A to E must be met

These criteria replace the previous definition from 2005.

Treatment and Management

There is no cure for KLS at present. KLS usually ends spontaneously but episodes may continue for ten years or more.


There are currently no recommended medications. Occasionally some medications may be prescribed by specialists for use during some episodes to try and reduce particularly troublesome symptoms.

Since some KLS sufferers can become sleepy and behave strangely they may find it comforting to wear medical jewellery or bands with their full name, Kleine-Levin Syndrome KLS and a very brief explanation of symptoms (and medication if any). One lad wore this medical neck jewellery in the years he was having episodes. There are quite a few companies now, so there is plenty of choice for boys, girls, men and women, just search on the internet and make your choice. There is an example of wording below.

male medical jewellery

Image of the medical card with other cards

KLS Support UK Medical Cards

KLS Support UK have produced a card which can be printed off, filled in and carried in a wallet/purse. Many of those suffering from KLS, especially youngsters, are reluctant to be 'labelled' with an illness and do not want to wear medical jewellery. With this simple card all the relevant details can be kept safely on them at all times. Link

KLS Diagnostic criteria International Classification of Sleep Disorders definition (2005).
Coping strategies for carers This helpful guide from KLS Support UK can be downloaded and printed.
KLS Case Histories by Lily, Ben, Nathalie and Elliot.
Articles about UK KLS sufferers
KLS on YouTube
Who named it? a link externally to whonamedit.com, an online dictionary of medical eponyms.

Please make contact using KLS Support UK's Contact Us form. Thank you.