Narcolepsy
Introduction
Narcolepsy is a long-term (chronic sleep) disorder that disrupts your normal sleeping pattern. Symptoms of narcolepsy can be mild or severe, and include:
- falling asleep suddenly, and without warning (known as 'sleep attacks')
- excessive daytime sleepiness (EDS)
- temporary muscle weakness when responding to emotions such as laughter and anger (cataplexy)
How common is narcolepsy?
It is not known exactly how common narcolepsy is, largely because the condition often goes unreported, or is not diagnosed correctly. However, it is a relatively rare condition.
It is estimated that narcolepsy affects 1 in 2,000 people worldwide, which is the equivalent of 25,000 people in the UK. It is also estimated that around 80% of people with the condition are undiagnosed.
Narcolepsy affects men and women equally. The condition usually begins during adolescence (the teenage years), although it can sometimes start earlier. Cases of narcolepsy that have started later (during middle age) have also been reported.
Outlook
There is currently no cure for narcolepsy, but if you have the condition, there are a number of treatments which can help to effectively manage your symptoms, and minimise the impact the condition has on your daily life.
Narcolepsy does not usually cause any long-term physical health problems, but it can have a significant affect on your personal and professional life.
If you have narcolepsy, you must stop driving immediately. It is your legal obligation to inform the Driver and Vehicle Licensing Agency (DVLA) about a medical condition that might have an impact on your driving ability. The Directgov website has information about how to tell the DVLA about a medical condition.
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Symptoms
The symptoms of narcolepsy can vary from person to person. Some people experience symptoms very frequently, while others are less severely affected.
Daytime sleepiness
In most cases of narcolepsy, daytime sleepiness is the first symptom to appear. It is often the most debilitating symptom.
If you have daytime sleepiness, you will feel drowsy throughout the day and have difficulty staying awake.
Sleep attacks
One of the most common symptoms of narcolepsy is falling asleep suddenly and without warning.
People with narcolepsy often experience these sudden 'sleep attacks' after eating, although they can occur at any time. Typically, during a sleep attack, you will fall asleep for approximately 15 minutes before waking up feeling alert and refreshed. The length of time that a sleep attack can last for will vary from person to person, and they can occur several times a day.
Other symptoms
As well as daytime sleepiness and sleep attacks, narcolepsy can cause a variety of other symptoms including:
- temporary muscle paralysis (being unable to speak or move) when falling asleep or waking up
- hallucinations – seeing or hearing things that are not real
- difficulty concentrating
- restless night time sleep – for example, having hot flushes,
- frequently waking, having vivid nightmares and physically acting out your dreams
- automatic behaviour – when you continue to carry out normal activities, such as talking, or moving around, while you are still asleep
Cataplexy
Approximately 75% of people who have narcolepsy also experience cataplexy. Cataplexy is a condition that causes sudden, but temporary, muscle weakness or a loss of muscular control. For example, during a cataplexy attack, you may find that:
- your jaw drops
- your head slumps down
- your legs collapse uncontrollably
- your speech is slurred
Cataplexy attacks are normally triggered by an emotion, such as excitement, laughter, or fear. The attacks can last for a few seconds, or they may continue for several minutes. Some people with narcolepsy have cataplexy attacks once or twice a year, while others have them several times a day. The symptoms of cataplexy can sometimes improve with age.
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Causes
The exact cause of narcolepsy is not yet fully understood. Some studies have suggested that it could be a genetic disorder (a condition that is passed on from one family member to another).
A number of other factors may contribute to causing narcolepsy. However, before discussing these factors, it is useful to compare what happens during a normal sleep pattern to what happens during a sleep pattern that is affected by narcolepsy.
Normal sleep pattern
When you fall asleep, your body goes through two main stages:
- non-rapid eye movement (NREM) is the first stage
- rapid eye movement (REM) is the second stage
During NREM, your brain activity slows down. You will normally be in NREM sleep for approximately 1-2 hours before entering REM sleep. During REM, your brain activity starts to increase and dreaming can occur.
Narcolepsy sleep pattern
If you have narcolepsy, you do not have NREM sleep. Instead, your body immediately enters the second stage of sleep (REM). This means that people with narcolepsy often start having vivid dreams almost as soon as they fall asleep. People with narcolepsy also go into REM sleep at inappropriate times.
Brain chemicals
Some research has suggested that narcolepsy may be caused by an imbalance of chemicals in your brain. Chemicals, such as hypocretin, are responsible for regulating your sleep. Hypocretin helps you to wake up after you have been sleeping, and then ensures that you stay awake.
Tests have shown that people with narcolepsy have lower than average levels of hypocretin in their brain, which scientists believe is one of the factors which causes irregular sleep patterns.
It is not known why the brain chemicals become imbalanced in people with narcolepsy. However, one theory is that it may occur as a result of the immune system attacking the cells which produce hypocretin. The immune system normally protects the body from illness and infection, but sometimes it can attack the body's own healthy tissues and cells as well.
Other causes
More than half of people with narcolepsy have reported an important event in the days or weeks before the onset of their symptoms. These include:
- pregnancy
- a major psychological stress
- a sudden change of sleep pattern
- a head trauma
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Diagnosis
Visit your GP immediately if you think that you have narcolepsy. When you see your GP, take a sleep diary with you and/or a completed Epworth sleepiness questionnaire (see below).
In order to diagnose narcolepsy, your GP will take a close look at your medical and family history. They will ask you about your sleeping habits and any other symptoms that you are having.
The symptoms of narcolepsy usually first appear during the teenage years, and are often mistakenly attributed to 'typical teenage behaviour'. For example, if a pupil falls asleep in class, it may be assumed that they are staying up too late at night and that they are not getting enough sleep.
Ruling out other conditions
Narcolepsy is sometimes a difficult condition to diagnose. Its symptoms can often be attributed to other conditions, such as anaemia (a condition that causes a reduced number of oxygen carrying red blood cells) or epilepsy (a condition that causes repeated seizures or fits).
Therefore, in order to make a correct diagnosis, your GP may carry out several tests to help rule out any other conditions that may be causing your excessive daytime sleepiness. For example, you may require a blood test or an X-ray.
Some medical conditions that can cause excessive daytime sleepiness include:
- head trauma
- stroke– a serious medical condition caused by the blood supply to the brain being disturbed
- inflammatory conditions – any condition that causes inflammation (swelling)
- neurodegenerative conditions – disorders of the nervous system
Excessive daytime sleepiness can also sometimes be caused by the side effects of certain prescription medicines and those bought over-the-counter (OTC).
Sleep analysis
To confirm a suspected case of narcolepsy, you will usually have an in-depth analysis of your sleep patterns. In order to do this, your GP will refer you to a specialist in sleep disorders. Your sleep can be analysed in a number of ways, some of which are outlined below.
Epworth sleepiness scale
The Epworth sleepiness scale is a questionnaire that can help analyse the situations that make you feel sleepy. Your GP will use the results of your completed questionnaire to help them decide whether you to refer you to a sleep specialist.
In filling out the questionnaire, you are asked to rank your likelihood of falling asleep in situations such as sitting and reading, watching television or being a passenger in a car. The specialist will look at your answers to determine whether you are unusually drowsy or whether your sleep pattern is fairly normal.
A score of 10 or below indicates that you have a level of daytime sleepiness that is equal to the general population. However, a score of 18 or above indicates that you have a high level of daytime sleepiness. If this is the case, it is likely that your GP will refer you to a sleep specialist for further investigation.
Polysomnography
Polysomnography is an investigation of your sleep, which is carried out at a specialist sleep centre.
The study usually involves staying overnight at the sleep centre in order to measure your sleeping patterns. During your night time sleep, several different parts of your body will be carefully monitored.
Specialist nurses will place a series of electrodes (small metallic discs) and bands on the surface of your skin and around parts of your body. Electrodes and bands will be placed:
- on your face and scalp (electrodes)
- above the lip (electrodes)
- around the chest (bands)
- around your abdomen (bands)
Sensors will also be placed on your legs and an oxygen sensor will be attached to your finger.
The tests that will be carried out during polysomnography include:
- electro-encephalography (EEG) – this monitors your brain waves
- electromyography (EMG) – this monitors your muscle tone
- recordings of thoracic-abdominal movements – movements in your chest and abdomen
- recordings of your oro-nasal airflow – the airflow through your mouth and nose
- rulse oximetry – this measures your heart rate and blood oxygen levels
- electrocardiography (ECG) – this monitors your heart
- Sound and video recording
After you have slept, a specialist will analyse your test results to see whether you have normal brain wave activity, breathing patterns and muscle and eye movement.
Multiple sleep latency test
A multiple sleep latency test measures how long it takes for you to fall asleep during the day. You may have this test after having a polysomnogram.
If you have a multiple sleep latency test, you will usually be asked to have several naps throughout the day and a specialist will analyse how quickly and easily you fall asleep. If you have narcolepsy, you will usually fall asleep easily and enter rapid eye movement (REM) sleep very quickly.
Narcolepsy with cataplexy
If your GP thinks you may have narcolepsy with cataplexy (temporary muscle weakness), you will be referred to a specialist centre in order to confirm the diagnosis. A diagnosis of narcolepsy with cataplexy will be based on the following criteria:
- you are have excessive daytime sleepiness (EDS), which has happened daily for at least three months
- you have a history of cataplexy (sudden episodes of muscle weakness on both sides of your body that last for less than two minutes and are triggered by emotions)
- your symptoms are not caused by a different sleep condition or medical disorder
Narcolepsy with cataplexy can sometimes be confused with other conditions, such as:
- narcolepsy without cataplexy
- sleep apnoea – a condition that causes interruptions to breathing during sleep
- hypersomnia – an excessive need to sleep
- chronic sleep deprivation – not sleeping for long periods of time
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Treatment
There is currently no cure for narcolepsy. However, there are a number of ways that you can manage your symptoms in order to minimise the impact that narcolepsy has on your daily life.
Sleep habits
One of the best ways to help manage excessive daytime drowsiness is to take frequent, brief naps, that are evenly spaced throughout the day.
This may not always be possible in a work or school situation. However, your GP should be able to assist you devise a sleep schedule, which will help your body get into a routine of taking naps.
Also make sure that you stick to a strict bedtime routine. Whenever possible, go to bed at the same time each night, and try to get at least eight hours sleep every night. This will help your body to get into a regular routine, and make your night time sleep less disturbed.
Lifestyle
There are a number of lifestyle changes that you can make to help manage your narcolepsy symptoms. These include:
- avoiding stressful situations because stress can make your condition worse
- eating a healthy, balanced diet because this can help to improve your levels of alertness
- avoiding heavy meals during the day and before doing any potentially dangerous activities, such as operating machinery
- taking regular exercise and not exercising within three hours of going to bed
If your child has been diagnosed with narcolepsy, inform their school teachers. It is important that your child’s school is made aware of the diagnosis so that they do not mistakenly interpret your child’s behaviour as a lack of sleep or laziness.
Stimulants
If your GP feels it is necessary, they may prescribe you a type of medicine known as a stimulant.
Stimulants work by stimulating the central nervous system. They may be prescribed if you have narcolepsy because they can help to keep you awake during the day.
The stimulants most commonly prescribed for narcolepsy are:
Modafinil and dexamphetamine are not recommended for women who are pregnant or breastfeeding.
Although they are usually effective, stimulants can cause common side effects such as:
- nervousness
- irregular heart beats (palpitations)
- headache
- dizziness
- dry mouth
- nausea
- stomach pain
- indigestion
- diarrhoea
- constipation
- tiredness and difficulty sleeping
- pins and needles
- blurred vision
You should talk to your GP if you experience these side effects while taking a stimulant medicine. They may be able to prescribe an alternative medicine for you.
Sodium oxybate
Sodium oxybate is a medicine that treats narcolepsy with cataplexy (temporary muscle weakness) in adults. You may be prescribed it if you are having sleep problems during the night.
If you are prescribed sodium oxybate, you will have to take two doses each night, the first when you get into bed and the second two-and-a-half to four hours later (you may need to use an alarm clock to ensure that you take the medicine at the right times).
You will need to take sodium oxybate two to three hours after having a meal because eating food can affect the amount of medication that is absorbed into your body.
Avoid drinking alcohol while you are taking sodium oxybate. Tell your GP if you are taking other prescription medications or over-the-counter (OTC) medication.
Sodium oxybate is not recommended for pregnant women and women who are breastfeeding. Inform your GP if you are pregnant or you are planning on getting pregnant.
Avoid doing any activities that require mental alertness, such as driving or operating heavy machinery, until at least six hours after taking sodium oxybate.
Very common side effects of sodium oxybate include:
- nausea
- dizziness
- headaches
Common side effects include:
- blurred vision
- trembling
- vomiting
- diarrhoea
- abdominal (tummy) pain
- nightmares
Uncommon side effects include:
- psychosis – a condition that affects a person’s mind and changes the way that they think, feel and behave
- paranoia – when you are suspicious of people and situations
- hallucinations – seeing or hearing things that are not real
- abnormal thinking
- weight loss
- agitation
- restless legs syndrome – a condition that causes uncomfortable sensations in the legs
Inform your GP if you are taking sodium oxybate and you have severe or troublesome side effects
Antidepressants
Although antidepressants are most commonly used for treating depression, they can also be used to treat a number of other conditions, including narcolepsy.
However, recent studies have questioned the effectiveness of using antidepressants to treat narcolepsy, with or without cataplexy. Some experts feel that more trials need to be conducted in order to test the usefulness of antidepressants.
Antidepressants may be used if your narcolepsy causes you to have sudden loss of muscle control (cataplexy). See the 'symptoms' section for more details about cataplexy.
Antidepressants should help to reduce the number of hallucinations that you experience. They can also help treat temporary muscle paralysis when you fall asleep or wake up. However, antidepressants will not decrease the number of sleep attacks you have, and they will not make you feel more alert and awake, like a stimulant medicine.
Antidepressants that are sometimes used to treat cataplexy are:
- tricyclic antidepressants
- selective serotonin reuptake inhibitors (SSRIs)
Tricyclic antidepressants
The types of tricyclic antidepressant that are most commonly prescribed to treat the symptoms of cataplexy are:
- imipramine
- desipramine
- clomipramine
- protriptyline
Tricyclic antidepressants are not addictive. Common side effects of this type of antidepressant can include:
- constipation
- difficulty urinating
- blurred vision
- dry mouth
- weight gain or weight loss
- drowsiness
- sweating
- lightheadedness
- skin rash
Contact your GP if these side effects do not ease within 7 to 10 days after starting the treatment.
Selective serotonin reuptake inhibitors (SSRIs)
Selective serotonin reuptake inhibitors (SSRIs) are a type of antidepressant that work by increasing the level of a chemical in your brain called serotonin. The side effects of SSRIs are milder than tricyclic antidepressants.
Common side effects of SSRIs include:
- nausea
- headaches
- low sex drive
- blurred vision
- diarrhoea or constipation
- dizziness
- dry mouth
- loss of appetite
- sweating
- feeling agitated
- insomnia (being unable to sleep)
- abdominal (tummy) pain
Speak to your GP if your side effects have become worse and are showing no signs of returning to normal levels after a few days.
Over-the-counter (OTC) medicines
Some over-the-counter (OTC) medicines, such as cold and allergy medicines, can cause drowsiness as a side effect. Therefore, if you have narcolepsy, avoid taking these types of medicine because they are likely to make your daytime drowsiness worse.
If you are unsure about which medicines cause drowsiness, speak to your pharmacist, or your GP. They should be able to advise you about alternative medicines that do not cause drowsiness.
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Complications
Having narcolepsy should not cause you any serious, or long-term, health problems. However, the condition can have a significant impact on your daily life, and it is not uncommon for those with narcolepsy to struggle to deal with it on an emotional level.
School and work
As narcolepsy can make you feel very drowsy during the day, you may find it difficult to concentrate at work, or school.
Although narcolepsy does not affect intelligence, children with the condition may find it difficult to keep up with their classmates or do their homework if they continually feel drowsy.
If colleagues at work or school do not understand your condition, they may perceive you as being lazy, lethargic or rude. Therefore, explain your condition to your friends, colleagues and your employer so that they have a better understanding of how your symptoms affect you.
Relationships
Some people with narcolepsy find that it affects their relationships. Excessive drowsiness can lead to you having a low sex drive. Some men experience impotence (an inability to get and maintain an erection).
Emotional withdrawal
If you experience cataplexy (a sudden loss of muscle control) as a symptom of narcolepsy, you may find that it is triggered when you experience intense emotions, such as excitement, laughter or anger.
As cataplexy can be embarrassing and disorientating, you may withdraw from situations where your emotions are likely to be triggered. This can leave you feeling isolated.
If you have to stop driving because of your narcolepsy, it may also add to your feelings of isolation. Not driving may make it more difficult for you to get around, and to socialise with others.
Depression
If you are feeling depressed, or low, because of your narcolepsy, make sure that you tell your GP.
They should be able to put you in touch with a narcolepsy support group or organisation. Your GP can also offer advice and guidance about how you can minimise the effect that narcolepsy has on your daily life.
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