What is narcolepsy?
Narcolepsy is a sleep disorder where a person suddenly falls asleep at inappropriate times.
It is a long-term neurological condition that disrupts normal sleeping patterns.
The symptoms of narcolepsy can range from mild to severe and may include:
- sleep attacks – falling asleep suddenly, without warning
- excessive daytime sleepiness
- cataplexy – temporary muscle weakness in response to emotions such as laughter and anger
Read more about the symptoms of narcolepsy.
What causes narcolepsy?
Many cases of narcolepsy are now known to be caused by an autoimmune response.
This is where antibodies (infection-fighting proteins) are released by the body, but instead of destroying disease-carrying organisms and toxins, they attack healthy cells and tissue.
In the case of narcolepsy, antibodies attack areas of the brain that produce a sleep-regulating chemical called orexin (also known as hypocretin). This leads to a deficiency in orexin, resulting in narcolepsy (in particular, narcolepsy with cataplexy).
However, research has shown some people with narcolepsy still produce near-normal levels of orexin. In these cases, the exact cause remains unclear.
Read more about the causes of narcolepsy.
To correctly diagnose narcolepsy, your doctor will closely examine your medical and family history. They will ask about your sleeping habits and any other symptoms you have.
Your doctor may also carry out tests to help rule out other underlying conditions that could be causing your excessive daytime sleepiness.
If your doctor thinks you have narcolepsy, you will be referred to a sleep disorder specialist for an in-depth analysis of your sleep patterns.
Read more about sleep analysis and diagnosing narcolepsy.
There is currently no cure for narcolepsy. However, you can manage your symptoms and minimise the impact the condition has on your daily life.
Taking frequent, brief naps evenly spaced through the day is one of the best ways to manage excessive daytime drowsiness. This may be difficult when you are at work or school, but your doctor should be able to devise a sleep schedule that will help your body get into a routine of taking naps.
Keeping to a strict bedtime routine can also help. Whenever possible, you should go to bed at the same time each night, and try to get at least eight hours sleep a night. This will enable your body to get into a regular routine and help ensure your night-time sleep is less disturbed.
Read more about treating narcolepsy.
If you have narcolepsy, it should not cause serious or long-term health problems. However, the condition can have a significant impact on your daily life.
Many people with narcolepsy find it difficult to deal with the condition on an emotional level, which can cause problems at home, work or school.
Tell your doctor if narcolepsy is making you feel low or depressed. As well as providing advice, they may put you in touch with a narcolepsy support group in your area or a national organisation, such as Narcolepsy UK.
You must stop driving immediately if you have narcolepsy. It is your legal obligation to inform your driving licence issuer about any medical condition that might have an impact on your ability to drive.
Symptoms of narcolepsy can vary from person to person. Some people have frequent symptoms, while others are less frequently affected.
Excessive daytime sleepiness
In most cases excessive daytime sleepiness is the first symptom to occur. It is often the most debilitating symptom.
If you have excessive daytime sleepiness, you will feel drowsy throughout the day and have difficulty staying awake.
Sleep attacks, where you fall asleep suddenly and without warning, are also a common symptom of narcolepsy. They often occur after eating, although you may experience one at any time.
The length of time a sleep attack lasts will vary from person to person. During an attack, you may fall asleep for about 15 minutes before waking up feeling alert and refreshed. You may have several sleep attacks a day.
As well as daytime sleepiness and sleep attacks, narcolepsy can cause a variety of other symptoms including:
- temporary muscle paralysis – known as cataplexy (see below); during an episode you will be unable to speak or move
- hallucinations – seeing or hearing things that are not real
- difficulty concentrating
- restless night-time sleep – for example, you may have hot flushes, wake up frequently and have vivid nightmares and/or physically act out your dreams
- automatic behaviour – continuing to carry out normal activities, such as talking or moving around, while you are still asleep
About three-quarters (75%) of people who have narcolepsy also experience cataplexy. Cataplexy is where you have a sudden, temporary muscle weakness or loss of muscular control. For example, during an attack your:
- jaw may drop
- head may slump down
- legs may collapse uncontrollably
- speech may be slurred
- eyesight may be impaired (you may have double vision or find it difficult to focus)
Cataplexy attacks are usually triggered by an emotion, such as excitement, laughter, anger or surprise. Attacks can last from a few seconds up to 30 minutes.
Some people with narcolepsy have cataplexy attacks once or twice a year, while others experience them several times a day. The symptoms of cataplexy sometimes begin to improve as you get older.
Causes of narcolepsy
Many cases of narcolepsy are now known to be caused by an autoimmune response to an antibody called trib 2. However, in some cases, the exact cause remains unclear.
Scientists believed for some time that the reduction in a sleep-regulating brain chemical called orexin (also known as hypocretin) played a significant role in narcolepsy. However, exactly what was causing the reduction remained uncertain for many years.
In 2010, scientists in Switzerland discovered that the reduction in orexin is caused by an autoimmune response to an antibody called trib 2.
An autoimmune response is where antibodies (infection-fighting proteins) are released by the body, but instead of destroying disease-carrying organisms and toxins, they attack healthy cells and tissue.
The trib 2 antibodies attack the areas of the brain that produce orexin (hypocretin). The attack leads to a deficiency in orexin, which results in narcolepsy and, in particular, narcolepsy with cataplexy (temporary muscle weakness).
Upon carrying out a series of tests, Swiss scientists found people with narcolepsy had a significant number of trib 2 antibodies compared with people who did not have narcolepsy.
The results confirmed that the increased production of trib 2 is directly responsible for the deficiency in orexin found in people with narcolepsy.
Another significant finding was the more trib 2 antibodies a person has, the more damage occurs to the areas of the brain that produce orexin, increasing the severity of the symptoms of narcolepsy.
These research results help explain the cause of narcolepsy in many cases. However, they do not explain why some people with the condition still produce near-normal levels of orexin.
Sleep consists of two natural cycles of brain activity known as non-rapid eye movement (NREM) and rapid eye movement (REM).
Upon falling asleep, most people begin with a period of NREM sleep, of which there are four stages (see below), followed by a short period of REM sleep.
One full sleep cycle consists of a progression through the four stages of NREM sleep before entering REM sleep. During REM sleep your brain activity starts to increase and dreaming may occur.
The four stages of NREM sleep are:
- stage 1 – light sleep during which your brain activity slows down; this stage may last five to 10 minutes
- stage 2 – light sleep during which your heart rate slows down and your body temperature decreases as the body prepares to enter deep sleep
- stages 3 and 4 – the deeper stages with stage 4 being deeper than stage 3; it is during these stages of NREM sleep that your body repairs tissue, builds bone and muscle and the immune system is strengthened
If you have narcolepsy, you will experience REM sleep much earlier than normal after falling asleep. For example, you may enter REM sleep during naps. The effects of REM sleep, such as dreaming and paralysis, may also occur while you are conscious as well as while you are asleep.
You should visit your doctor immediately if you think you have narcolepsy. Take a sleep diary with you or a completed Epworth sleepiness questionnaire (see below).
To diagnose narcolepsy, your doctor will take a close look at your medical and family history. They will ask about your sleeping habits and any other symptoms you are experiencing.
Symptoms of narcolepsy usually begin during teenage years and are often mistakenly attributed to 'typical teenage behaviour'. For example, if a pupil falls asleep in class, it may be assumed they are staying up too late and not getting enough sleep.
Ruling out other conditions
Narcolepsy can sometimes be difficult to diagnose because its symptoms may be attributed to other conditions, such as anaemia (a reduced number of oxygen-carrying red blood cells) or epilepsy (a condition that causes repeated seizures or fits).
Therefore, to correctly diagnose narcolepsy, your doctor may carry out several tests to rule out any other conditions that may be causing excessive daytime sleepiness. For example, you may need blood testsor an X-ray.
Medical conditions that can cause excessive daytime sleepiness include:
- head trauma
- stroke – where the brain's blood supply is interrupted
- inflammatory conditions – any condition that causes inflammation (swelling)
- neurodegenerative conditions – nervous system disorders
Excessive daytime sleepiness can also sometimes be caused by side effects of certain prescription medicines and those bought over the counter.
If your doctor thinks you have narcolepsy, they will refer you to a specialist in sleep disorders who will analyse your sleep patterns. There are a number of different ways your sleep can be analysed (see below).
Epworth sleepiness scale
The Epworth sleepiness scale is a questionnaire used to help analyse situations that make you feel sleepy. Your doctor will use the results of your completed questionnaire to decide whether to refer you to a sleep specialist.
When you fill out the questionnaire, you will be asked to rank the likelihood that you will fall asleep in situations such as sitting and reading, watching television and travelling as a passenger in a car.
A score of 10 or below indicates you have a level of daytime sleepiness equal to the general population. A score of 18 or above indicates you have a high level of daytime sleepiness. If this is the case, it is likely your doctor will refer you to a sleep specialist for further investigation.
The sleep specialist will use your responses to determine whether you are unusually drowsy or whether your sleep pattern is fairly normal.
Polysomnography is an investigation of your sleep, carried out at a specialist sleep centre.
The study usually involves staying overnight at the sleep centre so your sleeping patterns can be measured. During the night, several different parts of your body will be carefully monitored while you sleep.
Specialist nurses will place 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 your lip (electrodes)
- around your chest (bands)
- around your abdomen (bands)
Sensors will also be placed on your legs and an oxygen sensor attached to your finger.
Tests carried out during polysomnography include:
- electro-encephalography (EEG) – this monitors brain waves
- electromyography (EMG) – this monitors 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
- pulse oximetry – this measures your heart rate and blood oxygen levels
- electrocardiography (ECG) – this monitors your heart
Sound recording and video equipment may also be used to record sound and images.
After you have slept, a specialist will analyse your test results to determine 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.
You will be asked to take 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 doctor thinks that you may have narcolepsy with cataplexy (temporary muscle weakness), they will refer you to a specialist centre so that the diagnosis can be confirmed.
A diagnosis of narcolepsy with cataplexy will be based on the following criteria:
- you have excessive daytime sleepiness (EDS), which has occurred daily for at least three months
- you have a history of cataplexy (sudden episodes of muscle weakness on both sides of your body triggered by emotions and lasting less than two minutes)
- 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 where your breathing is interrupted while you are asleep
- hypersomnia – an excessive need to sleep
- chronic sleep deprivation – not sleeping for long periods of time
There is no specific cure for narcolepsy, but you can manage your symptoms to minimise the impact the condition has on your daily life.
One of the best ways to manage excessive daytime sleepiness is to take frequent, brief naps evenly spaced through the day.
Although this may not always be possible in a work or school situation, your doctor should be able to devise a sleep schedule that will help you get into a routine of taking naps.
Also make sure 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 adjust to a regular routine and ensure your night-time sleep is less disturbed.
Making lifestyle changes can also help manage your narcolepsy symptoms. These include:
- avoiding stressful situations – stress can make the condition worse
- eating a healthy, balanced diet can help improve your levels of alertness
- not eating heavy meals during the day and before doing any potentially dangerous activities, such as operating machinery
- taking regular exercise but stop at least three hours before you go to bed
Before going to bed try to relax – for example, by taking a bath. Keeping the area where you sleep quiet and free of distractions will also help.
Avoid anything that will make it more difficult for you to get to sleep, such as caffeine (found in tea, coffee and some fizzy drinks, such as cola). Avoiding alcohol), smoking and some prescription medicines may also help (ask your doctor or pharmacist for advice).
If your child has been diagnosed with narcolepsy, you should inform their school. It is important your child’s teachers are aware of the diagnosis so they do not mistakenly interpret your child’s behaviour as laziness or lack of sleep.
If necessary, your doctor may prescribe a type of medicine known as a stimulant. They work by stimulating your central nervous system.
Stimulants are sometimes prescribed for narcolepsy because they can help keep you awake during the day.
Modafinil and dexamphetamine are two stimulants most commonly prescribed for narcolepsy. Neither of these medicines are recommended for women who are pregnant or breastfeeding.
Although stimulants are usually effective, they can cause side effects including:
- palpitations (irregular heartbeat)
- dry mouth
- stomach pain
- tiredness and insomnia
- pins and needles
- blurred vision
Speak to your doctor if you experience side effects while taking a stimulant. They may be able to prescribe an alternative medicine for you.
Sodium oxybate is a medicine used to treat narcolepsy with cataplexy (temporary muscle weakness) in adults. You may be prescribed it if you are having sleep problems at 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 you take the medicine at the right times).
You will need to take sodium oxybate two to three hours after having a meal because food can affect the amount of medication absorbed into your body.
Avoid drinking alcohol while taking sodium oxybate. Inform your doctor if you are taking other prescription medications or over-the-counter medication.
Sodium oxybate is not recommended for pregnant women and women who are breastfeeding. Inform your doctor if you are pregnant or trying to get pregnant.
Avoid 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:
Common side effects include:
- blurred vision
- abdominal pain
Uncommon side effects include:
- psychosis – a condition that affects a person’s mind and changes the way they think, feel and behave
- paranoia – where you are suspicious of people and situations
- hallucinations – seeing or hearing things that are not real
- abnormal thinking
- weight loss
- restless legs syndrome – a condition that causes uncomfortable sensations in your legs
You should inform your doctor if you are taking sodium oxybate and experiencing severe or troublesome side effects.
Antidepressants are most commonly used to treat depression, but can also be used to treat other conditions, including narcolepsy.
Antidepressants may be recommended if you have narcolepsy and cataplexy (sudden loss of muscle control). Read more about the symptoms of cataplexy.
Antidepressants will also help reduce the number of hallucinations you experience, as well as helping to treat temporary muscle paralysis when you fall asleep or wake up. However, antidepressants will not reduce the number of sleep attacks you have, nor make you feel more alert and awake, like a stimulant.
Two types of antidepressants sometimes used to treat cataplexy are tricyclic antidepressants and selective serotonin reuptake inhibitors (SSRIs).
The types of tricyclic antidepressant that are most commonly prescribed to treat cataplexy are:
- [venlafaxine] (most commonly used)
Tricyclic antidepressants are not addictive but common side effects can include:
- difficulty urinating
- blurred vision
- dry mouth
- weight gain or weight loss
- skin rash
Contact your doctor if you have these side effects and they do not ease within seven to 10 days after starting 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 those of tricyclic antidepressants. Common side effects of SSRIs include:
- low sex drive
- blurred vision
- diarrhoea or constipation
- dry mouth
- loss of appetite
- feeling agitated
- abdominal pain
Visit your doctor if you have these side effects and they get worse and show no signs of returning to normal levels after a few days.
Some over-the-counter medications, such as cold and allergy medicines, can cause drowsiness as a side effect. Therefore, if you have narcolepsy, avoid taking these types of medicines because they may make your daytime drowsiness worse.
Speak to your doctor or pharmacist if you are not sure which medicines cause drowsiness. They will be able to recommend medicines that do not cause drowsiness.
Complications of narcolepsy
If you have narcolepsy, it should not cause serious or long-term health problems. However, it may have a significant impact on your daily life.
Sometimes, people with narcolepsy find it difficult to deal with the condition on an emotional level.
Work and school
You may find it difficult to concentrate at work or school because narcolepsy can make you feel very drowsy during the day.
Although narcolepsy does not affect intelligence, a child with the condition may find it difficult to keep up with their classmates or do their homework if they continually feel drowsy.
If other people do not understand your condition, they may think you are lazy, lethargic or rude. You should therefore explain your condition to your friends, colleagues and employer so they understand how your symptoms affect you.
Some people with narcolepsy find the condition affects their relationships. Excessive drowsiness can lead to loss of libido (a low sex drive). Men with narcolepsy may also experience impotence (an inability to get and maintain an erection).
If you have cataplexy (a sudden loss of muscle control) as a symptom of narcolepsy, you may find it is triggered during intense emotions, such as excitement, laughter or anger.
As cataplexy can be embarrassing and disorienting, you may avoid situations where your emotions are likely to be triggered. This may leave you feeling isolated.
If you have to stop driving due to having narcolepsy, it may add to your feelings of isolation. Not driving may make it more difficult for you to get around and to socialise with others.
You should tell your doctor if you have narcolepsy and it is making you feel depressed or low.
Your doctor will be able to advise how you can minimise the effect narcolepsy has on your day-to-day life. They will also be able to put you in touch with a narcolepsy organisation or support group.
Read more about depression.