Narcolepsy is a condition that can have a huge psychological, social and physical impact on those who have it. It is characterised by sleep attacks where sufferers fall asleep and sometimes drop to the ground without warning. Considerable progress has been made in the past thirty years to understand this rare, long term brain condition but there are still many unknowns.
What is narcolepsy?
Narcolepsy is a rare condition affecting the neurological system. The brain loses its ability to regulate sleep patterns resulting in a disturbed sleep-wake cycle. A person with narcolepsy may sleep as much as someone without but they constantly feel tired due to a lack of restorative sleep. They may involuntarily sleep at inappropriate times and suffer a range of other symptoms linked to this disrupted brain function.
Around one person in every 2,500 is affected by narcolepsy which means that in the UK, approximately 30,000 people have it. Because of the difficulties in diagnosing it, a poor awareness of the symptoms and the cross over with other conditions, there will be many who have it but are unaware of the diagnosis.
There are a wide range of symptoms that someone with narcolepsy might experience but the main ones that characterise the condition are:
Excessive day time sleepiness
Regardless of how much sleep they have had, sufferers feel unrefreshed and deprived of sleep leading them to feel exhausted throughout the day.
Sudden brief episodes of involuntary sleep lasting seconds or minutes can occur, without warning, at inappropriate times such as whilst driving or mid-conversation.
Around 70 per cent of people with narcolepsy will experience cataplexy; a sudden weakening of muscles. This can lead to complete collapse to the ground or be more centred on a group of muscles such as the vocal cords, making it impossible to speak or the eye muscles leading to blurred vision. It is usually triggered by intense emotion such as anger or laughter. The person remains conscious throughout. Cataplexy can last seconds or minutes and may happen once a year or multiple times a day.
On falling asleep or waking up, a person with narcolepsy may experience the frightening sensation of being awake but unable to move or speak. It can last several minutes and resolves on its own but it can be distressing especially as it can be accompanied by vivid hallucinations.
Night time sleep may be disrupted by frequent awakenings, vivid dreams and incessant twitching and moving of leg muscles. Insomnia, the inability to fall or remain asleep is often also present.
Who’s affected by narcolepsy?
Narcolepsy can begin at any age but it usually starts in adolescence with most people being given a diagnosis age 20 to 40. Generally, men and women are equally affected but some research shows a slightly higher incidence in men.
It can begin quite suddenly or there can be more of a gradual onset of symptoms. It is a lifelong condition but it doesn’t tend to worsen with age, some symptoms may in fact lessen as people get older.
Most cases of narcolepsy occur spontaneously but it does seem to run in some families suggesting a genetic cause for around 10 per cent of sufferers.
Narcolepsy can also be called ‘secondary narcolepsy’ where it begins as the result of another medical condition such as a brain injury.
The cause of narcolepsy is largely unknown and it is thought that a range of factors may work together.
The brain chemical hypocretin (also called orexin) has been found to be low in many people who have narcolepsy, particularly those who have cataplexy. Hypocretin helps to regulate sleep and makes us feel awake.
Things that trigger low hypocretin levels may therefore cause narcolepsy and these include:
There are many different autoimmune conditions where the body starts to recognise normal tissues as abnormal and begins to destroy them. In the case of narocolepsy, it attacks the area in the brain that produces hypocretin.
There do seem to be families where narcolepsy is inherited suggesting a genetic cause. It may be that the trait inherited is an inability to create or maintain adequate amounts of hypocretin.
Occasionally narcolepsy is the result of damage to the brain tissue from an injury or tumour affecting the parts of the brain that regulate sleep and wakefulness.
It’s still not understood why some people who have narcolepsy have normal levels of hypocretin. There are other possible triggers that may influence the development of narcolepsy. These include hormonal changes such as those seen during puberty and the menopause. Major emotional stress has been thought to be a trigger as have some infections including streptococcal infections, swine flu and encephalitis.
How is narcolepsy diagnosed?
The most important factor in making a diagnosis of narcolepsy is the description of the symptoms that the person is experiencing. This is called the ‘history’ of the presenting complaint. The doctor will want to know all the things that the patient has noticed and the timescales over which they have happened. History from a relative who is there if and when sleep attacks and night time symptoms happen is invaluable too.
A final diagnosis would be made by a specialist after a range of tests to try to confirm the condition. There are some of the tests that may be used:
Sleep study (polysomnogram)
Usually done overnight this test will record a number of measurements including brain wave activity, eye and muscle movements, oxygen levels and heart rate.
Multiple sleep latency test
This is done to work out how quickly someone falls asleep during a series of naps throughout the day. People with narcolepsy usually fall asleep rapidly and go into REM (rapid eye movement sleep) more quickly than those who don’t.
Hypocretin levels can be measured by taking a sample of the fluid that surrounds the spinal cord and brain, this is called cerebrospinal fluid. During a lumbar puncture a needle is inserted between the vertebrae of the lower spine and a sample of fluid drawn off and analysed.
Blood may be taken to look for the genetic markers that can be linked to narcolepsy. This does not give a definite diagnosis because 30 percent of people may have a positive result but not have narcolepsy but it can confirm and add evidence to a diagnosis.
What else could it be?
Many other conditions cause excessive daytime sleepiness and disruption of sleep patterns. These conditions include, sleep apnoea, major depression, alcohol excess and heart failure. Careful history taking, tests and investigations should be able to distinguish these from narcolepsy and lead to appropriate treatment ad management.
Narcolepsy is a life-long condition which cannot be cured but both lifestyle changes and medication can be used to minimise and control symptoms.
Lifestyle changes centre around improving sleeping habits as much as possible and include:
- Taking short naps throughout the day to reduce daytime sleepiness
- Using sleep hygiene which means going to bed and getting up at the same time every day
- Getting plenty of exercise (not within two hours of going to bed) to promote quality sleep
- Avoiding alcohol, caffeine and heavy meals for several hours prior to bed time
- Relaxing and unwinding before sleep and having a cool, calm bedroom
Medications used to treat narcolepsy are targeted at reducing the sleepiness in the day and controlling cataplexy.
Modafanil is a stimulant drug used to overcome daytime sleepiness. Like all stimulants it can result in headaches, shakiness, nausea and weight loss. There is a particular concern over its side effect of causing irregular heartbeats and high blood pressure so if used then careful monitoring needs to take place. It is not suitable for women who are pregnant or are trying to become pregnant because it is harmful to the unborn child.
Antidepressants may be beneficial. Tricyclic antidepressants and SSRIs (selective serotonin reuptake inhibitors) can reduce cataplexy. They may also reduce sleep paralysis and hallucinations.
Sodium oxybate is a sedative taken at night. It can help to reduce day time sleepiness and cataplexy. It is not currently funded by the NHS in the UK. There are numerous side effects including dizziness, stomach upsets and bed wetting.
It is important to get a diagnosis and access treatment for narcolepsy.
Undiagnosed and untreated narcolepsy carries a high risk of being involved in a motor vehicle accident or of suffering a serious fall. You should stop driving ad inform the DVLA (licensing agency) if you think you have narcolepsy. You may be able to start again once your condition is controlled.
Whilst there is no cure, much can be done to reduce symptoms and support those who have narcolepsy and their families too. Help and advice is available from local and national support groups such as Narcolepsy UK. Talking to others who are affected is an invaluable way to help cope with the huge impact that narcolepsy can have on everyday life.
Last medically reviewed: 24-06-2020
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