What is narcolepsy?
Narcolepsy is a serious but rare condition causing excessive sleepiness during the day and the possibility of 'sleep attacks', falling asleep at inappropriate times.
A person with narcolepsy has to tell the DVLA about the condition because of the risk of falling asleep at the wheel. Their circumstances will be assessed before being allowed to drive with the condition.
This long-term neurological condition also disrupts a person's normal sleep patterns.
At least 25,000 people in the UK have narcolepsy, with the diagnosis most common between the ages of 20 and 40.
What causes narcolepsy?
The cause of narcolepsy is not always known.
Many cases of narcolepsy are due to a deficiency in the production of a chemical called orexin or hypocretin by the brain,
Some cases of narcolepsy are caused by the body's autoimmune reaction to the trib 2 antibody.
Additionally, researchers have discovered abnormalities in various parts of the brain involved in regulating REM sleep. These abnormalities apparently contribute to the development of symptoms. According to experts, it is likely narcolepsy involves multiple factors that interact to cause neurological dysfunction and REM sleep disturbances.
What are the symptoms of narcolepsy?
Symptoms of narcolepsy include:
- Excessive daytime sleepiness (EDS): In general, EDS interferes with normal activities on a daily basis, whether or not a person with narcolepsy has sufficient sleep at night. People with EDS report mental cloudiness, a lack of energy and concentration, memory lapses, a depressed mood, and extreme exhaustion. This must be distinguished from sleep apnoea, which can cause similar symptoms.
- Cataplexy: This symptom consists of a sudden loss of muscle tone that leads to feelings of weakness and a loss of voluntary muscle control. It can cause symptoms ranging from slurred speech to total body collapse depending on the muscles involved and is often triggered by intense emotion, for example surprise, laughter, or anger.
- Hallucinations: Usually, these delusional experiences are vivid and they are often frightening. The content is primarily visual, but any of the other senses can be involved. When accompanying sleep onset these are called hypnagogic hallucinations, when they occur during awakening they are called hypnopompic hallucinations.
- Sleep paralysis: This symptom involves the temporary inability to move or speak while falling asleep or waking up. These episodes are generally brief lasting a few seconds to several minutes. Following an episode, people rapidly recover their full capacity to move and speak.
How is narcolepsy diagnosed?
A clinical examination and medical history are essential for a correct diagnosis of narcolepsy. However, none of the major symptoms is exclusive to narcolepsy. Several specialised tests, which can be performed in a sleep disorders clinic, are usually required before a diagnosis can be established. Two tests that are considered essential in confirming a diagnosis of narcolepsy are the polysomnogram (PSG) and the multiple sleep latency test (MSLT).