Narcolepsy means excessive daytime sleepiness. Most of us sometimes feel tired and sleepy during the day. But even when we feel this way we usually manage to overcome those feelings and carry out our usual activities, although perhaps a bit less efficiently than usual.
People with narcolepsy are different. They will often feel excessively tired and sleepy and have an overwhelming urge to nap at any time of the day. Naps may last for a few minutes or up to an hour or more, and the person may feel alert for several hours after a nap. This can happen several times every day, and it not related to how much (or how little) sleep a person gets each night.
Many people with narcolepsy also suffer from other symptoms such as cataplexy (a sudden loss of muscle function while conscious) or sleep paralysis (the inability to move any part of the body upon waking).
What causes narcolepsy and cataplexy?
The exact cause of narcolepsy is unknown, but it is thought to develop when the levels of a brain chemical called hypocretin are too low. Hypocretin promotes wakefulness, so when there’s not enough, a person can fall asleep. In some cases, narcolepsy runs in families.
When a person also has cataplexy, there appears to be a loss of the brain cells that produce hypocretin. The reason for this is unknown, but it is thought to be an auto-immune reaction, where the body’s immune system mistakenly starts to attack its own cells.
In rare cases narcoplexy is caused by a genetic defect, a traumatic injury to the brain or a brain tumour.
What are the symptoms of narcolepsy and cataplexy?
The symptoms of narcolepsy include:
- Excessive daytime drowsiness and sleepiness.
- Abrupt napping (‘sleep attacks’) during the day no matter how much a person sleeps at night.
- Difficulty staying awake for long periods of time.
- Cataplexy: sudden loss of muscle function while conscious.
- Sleep paralysis: a person temporarily can’t move any part of the body upon waking or when falling asleep.
- Hallucinations: hearing, seeing or feeling things that aren’t there; often happens when falling asleep or waking up.
- Disrupted night time sleep (especially trouble staying asleep) and other sleep disorders such as sleep apnoea.
- Automatic behaviour: continuing with a task (usually a task that a person does often) even though they are asleep. The person’s performance of the task will usually be impaired and they may not remember doing those things when they wake up.
- Overweight: people with narcolepsy are more likely to be overweight or obese.
Narcolepsy may also affect a person’s ability to perform normal daily activities. People can fall asleep doing absolutely anything, e.g. working, playing a game, walking, talking to someone, eating, driving or operating machinery. For this reason narcolepsy can be dangerous.
Cataplexy – a sudden loss of muscle function while conscious – can range from a brief sensation of weakness in certain areas of the body to a total collapse where all the muscles are affected, causing a person to fall down. No matter how severe the loss of muscle function is, the person remains fully conscious throughout the episode. Cataplexy can last for several seconds or minutes. It can occur spontaneously, but many people notice that it is triggered by sudden emotions, such as laughter, excitement fear or, anger. Cataplexy is the second most common symptom of narcolepsy (after excessive daytime sleepiness) and is thought to affect about 70% of people with narcolepsy.
Sleep paralysis – when a person can’t move their muscles or speak when waking up or falling asleep – may only last anywhere from a few moments to a few minutes. A person with sleep paralysis may feel frightened because they can’t move, but it is not harmful and does not cause permanent paralysis. Sleep paralysis can also affect people who do not have narcolepsy.
Who gets narcolepsy and cataplexy?
Narcolepsy is thought to affect about 1 person in every 2,000 in Australia. Narcolepsy and cataplexy usually begin in young people aged in their teens or early twenties, but can develop in later life. It affects both males and female equally. Typically, a person with narcolepsy will have excessive daytime sleepiness as the first symptom and develop cataplexy several weeks or months later. However, about 10% of people experience cataplexy as the first symptom.
How are narcolepsy and cataplexy diagnosed?
Narcolepsy can sometimes be difficult to diagnose. Excessive daytime sleepiness can also occur because of other medical conditions such as infections, mood disorders such as depression, chronic illnesses such as anaemia and congestive heart failure, and other sleep disorders such as sleep apnoea. Alcohol, nicotine, caffeine and some medicines can also lead to excessive daytime sleepiness. When cataplexy is not present, a doctor may have to rule out other causes of daytime sleepiness before they can diagnose narcolepsy.
If a doctor thinks someone has a sleep disorder they will usually refer them to a sleep specialist for tests. The sleep specialist will most likely perform a sleep study (called a polysomnogram) and a multiple sleep latency test (MSLT).
- A polysomnogram is an overnight test that takes continuous measurements while the person is asleep. It is used to see if there are abnormalities in the sleep cycle.
- A multiple sleep latency test (MSLT) is performed during the day. As part of the test, the person is asked to take four or five short naps about 2 hours apart. The test measures how long it takes to fall asleep and whether a person falls into a deep sleep straight away.
How are narcolepsy and cataplexy treated?
There is no cure for narcolepsy or cataplexy but some of the symptoms may be controlled. In Australia, wake-promoting medicines may be prescribed to manage symptoms, for example:
- Stimulants: medicines that stimulate the central nervous system e.g. modafinil (Modavigil), armodafinil (Nuvigil), dexamphetamine sulphate (Dexamphetamine), methylphenidate hydrochloride (Concerta ER, Ritalin)
- Antidepressant medications: may help to manage cataplexy, sleep paralysis and hallucinations in people with narcolepsy e.g. clomipramine hydrochloride (Clomipramine, Placil, Arafranil).
Wake-promoting medicines are not usually enough on their own to control symptoms and a person will have to employ other techniques.
Self management is important. It may help the person with narcolepsy to schedule regular short naps (‘power naps’) during the day so that they remain alert and awake at other times. It may also be necessary to try to avoid situations where falling asleep is dangerous, e.g. driving. AustRoads has a section on narcolepsy in its Fitness to Drive guidelines. Someone with cataplexy may learn to recognise triggers and try to avoid or minimise these when possible.
What are the complications of narcolepsy and cataplexy?
A person with narcolepsy and cataplexy may have problems both socially and professionally. Other people may think the person with narcolepsy is lazy or not interested in things. People with narcolepsy may have a low sex drive and can even fall asleep during sex. People with cataplexy may withdraw from social situations or activities to avoid feelings and emotions that bring on an attack. People can harm themselves or others if they fall asleep while driving or operating machinery.
There are Australian support groups that help people with narcolepsy and cataplexy. Some offer counselling and advice, information, meetings and the support of other people who suffer from narcolepsy.