Narcolepsie et cataplexie

What are narcolepsy and cataplexy?

Narcolepsy is a long-term (chronic) sleep problem. Your sleep is affected so that you feel excessively tired and drowsy during the daytime but have disturbed night-time sleep. You can also have sleep attacks where you fall asleep during the day without any warning. The name comes from the Greek 'seized by somnolence' (somnolence is another word for drowsiness).

Many people with narcolepsy also have cataplexy. Cataplexy is the sudden loss of strength and control of some of your muscles whilst you are awake.

What are the symptoms of narcolepsy?

Excessive daytime sleepiness

This is the main symptom. It is normal to become a little sleepy during boring situations - for example, whilst you are sitting on the sofa watching TV in the evenings. However, if you have narcolepsy, you feel very sleepy a lot of the time, even in situations when you are active - for example, whilst driving, talking or eating.

You have no control over the sleepiness and you can have sleep attacks where you fall asleep with no warning. These sleep attacks or naps can happen a number of times a day and can last from a few minutes to an hour. You usually feel refreshed when you wake up but can soon become sleepy again.

Cataplexy

About 7 in 10 people with narcolepsy also have cataplexy. In cataplexy, you suddenly lose the strength and control in some of your muscles whilst you are awake. For example, it can mean that you suddenly nod your head, your knees may suddenly give way, you may drop something that you are holding or, in extreme cases, you may suddenly fall to the ground.

Emotions such as laughter, elation and anger can trigger cataplexy. You still have awareness during the attacks. They usually last for under a minute but they can happen several times a day. Sometimes you can have twitching of your muscles during an attack and some people confuse this with a seizure. More information about seizures can be found in the following leaflet Épilepsie et crises.

Sleep-related hallucinations

Hallucinations occur when you, for example, see, hear or feel something that is not actually there. They can happen either as you are falling asleep (hypnagogic) or as you are waking up (hypnopompic). It may seem like you are having a vivid dream.

Disturbed sleep during the night

People with narcolepsy take the same amount of time to fall asleep at night as other people but they wake frequently. Because of disturbed night-time sleep, even though you may have frequent daytime naps, the total amount of time that you are asleep in 24 hours is about the same as normal. People with narcolepsy are also more likely to sleepwalk.

Paralysie du sommeil

In sleep paralysis, you are conscious but are unable to move your body (called paralysis) when you wake up from sleep. Sometimes it can occur as you are falling asleep. If someone touches you or speaks to you, the paralysis is relieved and you are able to move again. The paralysis just lasts for a minute or two. It does not affect your breathing and is not dangerous but can feel frightening.

Automatic behaviour

If you are feeling tired and sleepy, automatic behaviour (doing something without really thinking about it and without having any memory of it) happens more frequently. For example, you may be driving and you may drive to a different, or the wrong, destination. You might say something out of context in a conversation. In automatic behaviour, there is an increased chance that tasks that you are performing go wrong and this can lead to accidents.

Autres symptômes

Sleepiness can lead to problems with your memory and ability to concentrate. You may notice problems with your vision such as blurred or double vision. Weight gain is also more common in people with narcolepsy.

What causes narcolepsy?

If you have narcolepsy, your sleep-wake cycle is disrupted. The exact cause of this is uncertain.

It has been suggested that narcolepsy with cataplexy is a type of autoimmune disease. In autoimmune disease the body makes antibodies which damage normal cells in the body. In narcolepsy these antibodies damage cells in the brain that produce hypocretin. Hypocretin is a neurotransmitter which helps control your sleep-wake cycle. It has also been suggested that other things such as a virus may trigger the damage to hypocretin-producing cells in people who have a higher chance of the condition because of their genes within their DNA. About 2 in 100 people with narcolepsy have a close family member with the condition.

How common is narcolepsy?

Narcolepsy is not common. It is thought to affect around 25-50 people per 100,000. It is most commonly diagnosed in your teenage years but has been diagnosed in younger children.

Narcolepsy affects both men and women in equal numbers.

How may narcolepsy affect my life?

Narcolepsy affects different people in different ways. Some people can have more severe symptoms than others.

Many people with narcolepsy find their symptoms embarrassing. In children it can affect their progress at school and can lead to teasing and bullying by their peers. If you are an adult, it may affect your ability to work. Sleepiness and memory problems may make your colleagues perceive you as lazy and lacking in motivation. Your relationships may also be affected. Your mood can be affected if you have narcolepsy, and depression or anxiety are common as a result of the disruption to sleep and life.

However, with the correct treatment, most people with narcolepsy do well. They are able to develop relationships, to work and to lead a productive life.

How is narcolepsy diagnosed?

Information from you or others

Your doctor will usually ask questions about your sleep. He or she may also ask if you or other people have noticed any signs that you may have cataplexy. They may ask about any medication that you are taking, any other health problems that you may have, whether you snore and also about your mood. This is to rule out other causes of excessive daytime sleepiness, including depression and l'apnée obstructive du sommeil. It can be helpful for your bed partner to be present (if you have one) when you talk to your doctor.

Your doctor may ask you to complete the Epworth Sleepiness Scale to assess how sleepy you are. A total score of 11 or more may mean that you have a sleeping disorder such as obstructive sleep apnoea. A very high score such as 17 or more may indicate that you have narcolepsy.

Sleep studies

If your doctor is concerned that you may have narcolepsy, he or she will usually refer you to a doctor who is a specialist so that you can have some sleep studies. This typically means you sleep overnight in a sleep laboratory and having a test called a polysomnogram.

Your heart, brain, muscles and eyes are monitored closely whilst you are sleeping overnight, using electrodes attached to your scalp, chin, eyelids and chest. A video camera may also record you while you are sleeping. This test can show your brainwaves, breathing patterns, eye and muscle movements and the phases of sleep that you cycle through during the night.

Your level of sleepiness the next day can also be measured using a test called the multiple sleep latency test. This test looks at how long it takes for you to fall asleep during the daytime. It is usual for people with narcolepsy to fall asleep very quickly when they are asked to try to take a nap. Other sleep tests may be performed.

Autres tests

Sometimes other tests may be done to confirm narcolepsy, or to rule out other causes of excessive daytime sleepiness. These can include:

• Des lumbar puncture. (A needle is pushed through the skin and tissues between two bones of your spine (vertebrae) into the space around the spinal cord which is filled with cerebrospinal fluid.) This is to measure the levels of hypocretin in the fluid around your brain and spinal cord.

• Une MRI scan of the brain.

• Analyses de sang.

What is the treatment for narcolepsy?

There is no cure for narcolepsy. However, treatment can help to control symptoms.

Advice

• Sleep routines. Having a regular sleep routine and a fixed daytime nap schedule can be helpful. Aim to have around eight hours of sleep at night if possible. You should try to go to sleep and get up at about the same time each day. Naps may only need to be 10-15 minutes long. You will often wake up feeling quite refreshed from a nap.

• Avoid eating heavy meals.

• Avoid drinking alcohol.

• Doing regular exercise.

• Communication with others. If you or your child are diagnosed with narcolepsy, you may find it helpful to communicate this to other people. Informing schoolteachers may help to explain your child's behaviour at school and get them any extra help that they may need. As an adult, explaining your diagnosis to your work colleagues can help them to understand. Some people arrange to include scheduled naps into their work or school routine.

• Addressing any mood symptoms. A low mood or anxiety is quite common in people who have narcolepsy. If you are feeling low, déprimé ou anxieux you should see your doctor. Mood symptoms are common in many chronic conditions and there are many options for improving these to help you feel more like your usual self.

Treatments using medicines

Modafinil

The most common medicine now used to treat sleepiness in narcolepsy is modafinil. It is a newer medicine that works as a stimulant and helps to stop you feeling as sleepy. Many people notice a good improvement in their symptoms when they take modafinil. It has the advantage that tolerance does not seem to develop as it can with the older stimulant medicines, described below. Modafinil also seems to have a lower rate of side-effects compared to the older medicines.

The most common side-effects include headache, nausea and a feeling of a blocked or runny nose. Modafinil can also affect the oral contraceptive pill. If you are taking 'the pill' you should discuss this with your doctor.

Methylphenidate and amphetamines

Older stimulant medicines used to treat narcolepsy include methylphenidate and amphetamines. However, these medicines are not used as often now, as you can develop a tolerance to them. They may also affect your sleep at night and therefore reduce your total sleep time.

Oxybate de sodium

Various medicines can help to treat cataplexy if this is a problem. Commonly, a medicine called sodium oxybate is used. As well as helping with the symptom of cataplexy, sodium oxybate may also help with:

• Excessive daytime sleepiness.

• Disturbed night-time sleep.

• Seeing, hearing or feeling something that is not really there (hallucinations).

• Sleep paralysis (where you are conscious but unable to move your body).

It may sometimes be used in combination with modafinil. You should not drink alcohol if you are taking sodium oxybate.

Antidépresseurs

Some antidepressant medicines, including clomipramine et le Antidépresseurs inhibiteurs sélectifs de la recapture de la sérotonine (ISRS) tel que fluoxétine, may also be used if you have cataplexy. (Remarque: they are not used here because of depression. The way that these medicines work on the chemicals in the brain appears to also ease the symptoms of cataplexy.)

Autres traitements

If you or your child are diagnosed with narcolepsy, you may find it helpful to communicate this to other people. For example, informing schoolteachers may help to explain your child's behaviour at school and get them any extra help that they may need.

As an adult, explaining your diagnosis to your work colleagues and to your boss can also help them to understand. Some people arrange with their employer or school to include scheduled naps into their work or school routine. You may also find career counselling helpful.

A low mood is quite common in people who have narcolepsy. If you are feeling low or depressed, you should see your doctor. They may be able to help or to suggest other people who can help, such as a counsellor or psychologist.

Narcolepsy and driving

In the UK, you are required by law to let the Driver and Vehicle Licensing Authority (DVLA) know if you are diagnosed with narcolepsy. You should stop driving immediately and you should not start to drive again until the DVLA has reached a decision on your case.

For a regular (group 1) driving licence you will usually be allowed to drive when your symptoms are well controlled with medication but you will need to have a regular review. It is unusual for someone to be granted an LGV(HGV)/bus (group 2) licence if they have narcolepsy. Your case should be treated on an individual basis and it will depend on how well controlled your symptoms are.