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Narcolepsy

Background

Narcolepsy is a neurological condition that occurs in about 5 out of 10,000 people. It is caused by the brain's inability to regulate sleep-wake cycles normally. Affected individuals have an irresistible urge to sleep at different times of the day and often complain of feeling very tired. Narcolepsy is a life-long condition and rarely gets worse through a patient's life. With drug treatment and support from families, school and work, an affected individual can lead a near to normal life.

Credits

Medical text written August 2010 by Leena D Mewasingh, Consultant Paediatric Neurologist and Honorary Senior Clinical Lecturer, St Mary's Hospital, Imperial College Healthcare NHS Trust, London, UK.

What are the symptoms?

The main symptom in this condition is excessive daytime sleepiness. An affected child or young people can fall asleep at awkward times (eg at school, during meals or during an activity). They can sleep for a few seconds or minutes and occasionally for longer periods such as an hour or so.

In addition to excessive daytime sleepiness, narcolepsy is associated with:

  • cataplexy - this is a sudden loss of voluntary muscle tone usually triggered by emotions, laughter being the most common
  • hypnagogic/hypnopompic hallucinations - these are highly vivid hallucinations, often happening at the onset of sleep (hypnagogic) or on waking up (hypnopompic)
  • sleep paralysis - these are brief episodes of inability to move at the beginning or end of sleep.

Automatic behaviour (where individuals carry actions with a certain amount of purpose but don't remember doing so) is another common occurrence during the day. Presentation of narcolepsy symptoms can vary, which can make this condition difficult to diagnose and often with a significant delay.

What are the causes?

Although the cause of narcolepsy seems multifactorial, involving both genetic and environmental factors, there is nonetheless a strong link between affected individuals and certain HLA genotypes (combinations of genetic information that code for a protein called human leukocyte antigen).

Individuals with narcolepsy have also been shown to have lower levels of a protein called hypocretin in their brain. This protein is responsible for controlling appetite and sleep patterns.

How is it diagnosed?

A thorough history taking, including sleep and family history and a detailed clinical examination are the first step in making a diagnosis. This then needs confirming with polysomnography (a sleep study), which looks at sleep patterns overnight and a multi-sleep-latency testing (MSLT), which looks at sleep patterns during the day. For more detailed diagnostic criteria for narcolepsy see the proposal by the International Classification of Sleep Disorders.

How is it treated?

Although there is no cure for narcolepsy, early recognition and treatment can greatly improve the quality of life of patients and decrease the chances of psychological problems as a result of the condition.

A selection of drug treatments including modafinil, methylphenidate (trade names Ritalin and Concerta), amphetamine, dextroamphetamine, and a type of antidepressants called selective serotonin reuptake inhibitors (SSRIs) are some of the medications used to treat the excessive daytime sleepiness.

Other non-drug based treatments for narcolepsy include taking brief naps, making changes to diet, counseling and behavioural strategies. Whilst these can help, there is often a need for drug treatment too.

Inheritance patterns and prenatal diagnosis

Inheritance patterns
Although no specific gene(s) has so far been found in narcolepsy, there is strong evidence that this condition can run in families.

Prenatal diagnosis
None.

Is there support?

Narcolepsy UK

Tel: 0345 450 0394
Email: info@narcolepsy.org.uk
www.narcolepsy.org.uk

Narcolepsy UK is a Registered Charity in England and Wales No. 1144342. It provides information and support to people with narcolepsy.

Group details last updated February 2016.