Kleine-Levin syndrome: recurring episodes of extreme sleepiness

Kleine-Levin syndrome (KLS) is a very rare sleep disorder. The Evelina London Sleep Medicine Department, a NHS specialist children's service, says it often begins in teenage years and features episodes of extreme sleepiness, appetite, mood and behavioural changes. It places it among rare disorders characterised by excessive daytime sleepiness, often called hypersomnia, alongside narcolepsy.

The US National Organization for Rare Disorders (NORD) describes the syndrome as a need for excessive amounts of sleep, excessive food intake (compulsive hyperphagia) and behavioural changes, with symptoms that are cyclical. A person may go for weeks or months without symptoms. Because it is under-diagnosed, NORD says its true frequency is difficult to determine, though more than 500 cases had been reported in the medical literature at the time of its report.

The NORD report used here was last updated in 2007 and comes from the United States, so figures and treatment details may have moved on. UK specialist services are the best source of current advice.

NORD says onset of symptoms is extremely rapid and may persist for days to weeks, with approximately two to 12 episodes per year. During an episode people may sleep 18 to 20 hours a day and wake only to eat, urinate and defecate. They can be woken but may be irritable, listless or lacking emotion, and may appear confused or have slurred speech.

Other features described by NORD include compulsive eating, in which the person does not usually complain of hunger but will eat available food and often gains weight; in some cases an abnormally increased sex drive or loss of inhibition; and hallucinations or a sense of distorted reality, feeling detached from surroundings. Memory problems, inattentiveness, depression, aggression and anxiety can also occur.

Between episodes, NORD says most affected people show no symptoms, which is one of the features that distinguishes it from other forms of hypersomnia.

• Sleeping most of the day and night for days or weeks at a time.

• Confusion, irritability, apathy or slurred speech when awake.

• Eating much more than usual.

• Sometimes hallucinations, a feeling of unreality, or disinhibited behaviour.

• Return to normal between episodes.

The exact cause is unknown. NORD says it is speculated that symptoms may develop due to malfunction of the part of the brain that helps regulate sleep, appetite and body temperature, the hypothalamus. Some researchers have speculated about an autoimmune process, as in some cases it follows a flu-like illness. NORD cites a 2005 Stanford study which found 72 per cent of cases studied were preceded by symptoms of infection, and notes that in extremely rare cases more than one family member has been affected.

It primarily affects adolescents, usually around 16, and males appear to be affected three times as often as females, according to NORD. Symptoms usually become apparent in adolescence, and in some people subside with advancing age, most often by early adult life, while in others the disorder persists throughout adulthood.

NORD says KLS may be suspected on the basis of a thorough clinical evaluation and a detailed patient history, and that certain tests may be performed to rule out other conditions such as epilepsy, brain lesions, meningitis or encephalitis. The pattern over time, with repeated episodes and normal function in between, is central.

Evelina London says it runs a specialist service for children and young people with rare disorders of excessive sleepiness, with extensive diagnostic equipment including inpatient polysomnography and multiple sleep latency testing. Its service for these disorders notes that referral is for anyone with excessive daytime sleepiness.

Other conditions that can look similar include narcolepsy, idiopathic hypersomnia, sleep apnoea, depression and delayed sleep phase syndrome, which NORD lists among disorders with similar symptoms.

NORD says treatment is directed towards the specific symptoms in each individual, may require a team of specialists including paediatricians, psychiatrists, psychologists and neurologists, and is symptomatic and supportive. Stimulant medicines may give temporary relief from the need for excessive sleep, though they had no effect on associated behavioural changes. Lithium has been effective in some cases, with one report of five adolescents whose episodes of excessive sleep were shortened but who all relapsed while on treatment, and NORD stresses that more research is necessary on long-term safety and effectiveness.

Evelina London says children and young people with these conditions are cared for by a multidisciplinary team, with support groups and school input, and are moved to adult services through transitional clinics at 16. Because the condition often arrives in the middle of school years, liaison with schools and exam boards can be as important as medication.

For families, the unpredictability of episodes is often the hardest part. During an episode the person needs supervision and safe surroundings because of confusion, and should not drive. Many families find it helpful to keep a record of episode dates, triggers such as infections, and what helped, to share with the specialist team.

Because the condition is so rare, many children and families feel they are on their own; Evelina London describes peer support groups for exactly this reason. Mood and anxiety are part of the picture for many young people, and psychological support is a legitimate part of care.

In the UK, the route is usually via a GP or paediatrician to a specialist paediatric or adult sleep service, as the Evelina referral advice indicates. A few centres see most rare hypersomnia cases, so referral may be to a service outside your local area.

Private neurology and sleep services can offer earlier assessment, and some families seek a second opinion. Given how rare the condition is, the key question for any provider is how many cases of recurrent hypersomnia they have managed.