Narcolepsy is a chronic neurological disorder characterised by excessive daytime sleepiness and often an array of additional symptoms, including (but not limited to) cataplexy, sleep paralysis, hallucinations, sleep fragmentation, vivid dreams, poor memory, automatic behaviour and obesity. Narcolepsy is a disability that affects around 1 in 2500 people or approximately 30,000 people in the UK. There is currently no cure, although medication and lifestyle changes can make life more manageable.
What is the cause of narcolepsy?
In most cases of narcolepsy, there is a loss of neurons that produce hypocretin (also known as orexin), a neurotransmitter that plays a central role in the regulation of alertness, motivation and mood. The damage to this important signalling system is thought to be the result of an autoimmune attack arising from a combination of genetic predisposition and an insult to the immune system (by a pathogen like the influenza virus or, in rare cases, vaccination).
Idiopathic hypersomnia (IH) shares some of the same symptoms as narcolepsy, although its cause is not yet known.
What are the symptoms?
All people with narcolepsy experience excessive daytime sleepiness (EDS), characterised by persistent and overwhelming sleepiness during the daytime. The pressing need to sleep usually builds over minutes, but some people with narcolepsy can also experience “sleep attacks”, where the transition from wake to sleep occurs without warning.
The majority of people with narcolepsy will also experience cataplexy, a sudden loss of muscle tone triggered by intense, often positive emotions such as laughter or surprise. The severity and duration of a cataplectic attack varies widely between people but also from one situation to the next. It may cause the lips to quiver and eyelids to close, the jaw to drop and the head to slump, slurred speech and the complete inability to vocalise, paralysis of skeletal muscles and eventual collapse. Importantly, a person experiencing cataplexy will remain completely conscious throughout an attack (in contrast to sleep or epilepsy). The experience is not painful and recovery usually occurs in less than a minute with no obvious ill effects. For many people whose cataplexy cannot be controlled by medication, however, the repeated loss of control - sometimes dozens of times a day - is likely to affect confidence and self-esteem.
Many people with narcolepsy will also experience sleep paralysis on a regular basis, waking up to find themselves unable to move. This state is not dangerous and will usually resolve in a matter of minutes, but it can be extremely alarming and is often accompanied by terrifying hallucinations.
Sleep fragmentation is common, with vivid dreams and multiple awakenings drastically reducing the quality of night-time sleep. Such disruption to the sleep cycle may account for the poor memory reported by many people with narcolepsy.
When people with narcolepsy are tired, they can exhibit automatic behaviour, losing consciousness but still able to perform a routine tasks as if awake. This can be unsettling and affect confidence and self-esteem.
In narcolepsy, the prevalence of obesity is twice that of the general population, most likely owing to a drop in the metabolic rate that occurs following the loss of hypocretin.
How will this affect me?
Narcolepsy is a spectrum disorder, so the combination and extent of symptoms will vary from one person to the next and this can make it hard to diagnose. With a diagnosis, however, with routine visits to a sleep specialist, effective medication, support from family and friends, and reasonable adjustments at school, college, university or work, it is possible to reduce the disability caused by narcolepsy.
If you think you may have narcolepsy, you will need to describe all your symptoms to your GP and present your score on the Epworth Sleepiness Scale. If you have cataplexy, you should emphasise this – with a video, if possible – as it is the most unusual of narcolepsy’s many symptoms. Your GP will need to refer you to a specialist sleep centre for further tests.
At the sleep centre, you will stay overnight for a sleep study so that the specialist can monitor the activity of your brain while you sleep. The following day, it’s likely that you will perform a multiple sleep latency test (MSLT), which measures how easily you fall asleep during the daytime and looks for the unusual sleep architecture characteristic of narcolepsy, notably rapid eye movement or dreaming sleep within minutes of falling asleep. Some sleep specialists will also ask to take a lumbar puncture to measure the concentration of hypocretin in your cerebrospinal fluid.
Treatment involves two complementary approaches. Pharmacological treatments include stimulants that can help with the excessive daytime sleepiness and other drugs that prevent cataplexy. It can take many years for you and your sleep specialist to identify the most effective drug regime and dose. Non-pharmacological treatments involve lifestyle changes, such as maintaining good sleep hygiene, having a healthy diet and taking short, planned naps during the day.
Narcolepsy UK promotes accessibility to early diagnosis, quality treatments and emotional and practical support for people with narcolepsy and IH and their carers. According to the charity’s Narcolepsy Charter, “people with narcolepsy have the same rights to a full and rounded life as any other person without having to fight to make this happen.”