Do you frequently experience the following symptoms?
- Excessive sleepiness during waking hours for no apparent reason.
- Falling asleep in inappropriate situations such as when talking to someone, working or driving.
- Feeling weak or sudden collapse during periods of strong emotions (e.g. laughter, anger, fear).
- Vivid nightmares immediately before falling asleep or waking up.
- Paralysed immediately before falling asleep or waking up.
If you do, you may have a medical disorder known as narcolepsy.
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What is narcolepsy?
Narcolepsy is a neurological disorder in which the brain is unable to regulate the sleep-wake cycle normally.
As a result, patients experience overwhelming and uncontrollable urges to fall asleep at any time throughout the day, often during inappropriate circumstances. Because rapid eye movement (REM) or “dreaming sleep” also intrudes into the waking hours, patients may experience symptoms of cataplexy (sudden loss of voluntary muscle tone), vivid hallucinations during sleep onset or upon awakening and brief episodes of total paralysis at the beginning or end of sleep. The onset of symptoms is typically late teens or early twenties.
Why is narcolepsy important?
It is a chronic disorder that affects approximately 0.05% of the population. This translates to roughly one in every 2000 people affected in western European countries and North America.
Narcolepsy affects males and females equally. Although symptoms may appear at any stage in life, most patients first experience symptoms during adolescence. Narcolepsy has a profound impact on the lives of its sufferers. Untreated symptoms may seriously affect relationships, education, social life, personal wellbeing and safety, driving and employment. It has been estimated that about half of all people suffering from narcolepsy are actually undiagnosed. These people may experience even greater stresses in life.
What causes narcolepsy?
Whilst the cause of narcolepsy is not fully understood yet, scientists have found genes associated with this disorder. The likelihood of developing narcolepsy is increased if an individual has a particular type of genetic makeup, termed HLADQB1*0602.
However, normal individuals may also have this genetic makeup without developing narcolepsy. A recent important scientific discovery is that patients with narcolepsy lack a brain chemical called orexin (hypocretin), which normally stimulates wakefulness and also helps regulate sleep. Patients with narcolepsy appear to have a reduction in the number of brain cells that produce orexin. It is still unclear as to whether this is due to a degenerative or immune process. There has been research into the possible roles of infections, toxins, dietary factors, stress and hormonal changes in narcolepsy but without any answers at this stage.
It is important to differentiate between narcolepsy and rare medical conditions that may mimic narcolepsy, and that may result from traumatic injury, tumours or other disease processes that may affect parts of the brain involved in regulating sleep, particularly REM sleep. This will be part of the medical assessment by a physician.
What are the symptoms of narcolepsy?
The four classic symptoms of narcolepsy are:
Excessive daytime sleepiness: usually the first symptom to appear, and often the most troubling of all. The overwhelming and recurring need to sleep occurs at times when the person wants to be awake, even if there has been adequate sleep.
Cataplexy: sudden brief loss of muscle control ranging from slight weakness (head droop, facial sagging, jaw drop, slurred speech, buckling of knees) to total collapse. This may be triggered by intense emotion (most commonly laughter but sometimes also surprise, anger or fear) or strenuous athletic activity. 7 out of 10 patients with narcolepsy have cataplexy.
Hypnagogic/hypnopompic hallucinations: vivid and often frightening dreams and sounds immediately before falling asleep (hypnagogic) or waking up (hypnopompic). 25% of patients with narcolepsy report these occurrences.
Sleep paralysis: inability to talk or move for a brief period immediately before falling asleep or waking up. Most patients with narcolepsy suffer short-lasting partial or complete sleep paralysis, often accompanied by hypnagogic or hypnopompic hallucinations. One in three patients with narcolepsy may have sleep paralysis.
Do patients with narcolepsy sleep more than normal?
Narcolepsy is considered to be a disorder of the normal boundaries between the sleeping and waking states.
Contrary to common beliefs, patients with narcolepsy in fact do not sleep any more than a normal sleeper in a 24-hour period. However, the night-time sleep of patients with narcolepsy is often disturbed with tossing and turning, leg jerks, nightmares and frequent awakenings.
How is narcolepsy diagnosed?
An experienced physician can often make the diagnosis from the symptoms of the sufferer. Physical examination and investigations serve to exclude other conditions and to confirm the diagnosis.
Investigations may include:
Overnight polysomnogram (PSG): a regular sleep study at night to exclude other conditions such as obstructive sleep apnoea or severe periodic limb movements in sleep that may also cause excessive daytime sleepiness. Patients with narcolepsy may also have a faster onset of REM sleep, which typically occurs no sooner than 90 minutes after falling asleep in normal people.
Multiple sleep latency test: this is performed on the day after the PSG. It involves asking the patient to have five 20 minute naps throughout the day at two hourly intervals. A patient with narcolepsy will take an abnormally short time to fall asleep during the naps. REM sleep can appear during these naps, and if present are abnormal. Results of these findings will need to be carefully interpreted by your physician as a number of other conditions such as sleep deprivation, untreated sleep apnoea and effects of certain drugs may give similar findings. A urine test looking for drugs (prescribed and illicit) will be performed as part of this test.
Blood test: for HLA testing may be ordered by your physician. Remember that the HLA test for narcolepsy may be positive in people without narcolepsy as well.
What else could it be?
Cataplexy is very specific for narcolepsy whilst other symptoms such as hypnagogic orhypnopompic hallucinations and sleep paralysis may occur in people without narcolepsy as well. Excessive daytime sleepiness is even less specific as it may also afflict people with other medical conditions and depression.
How is narcolepsy treated?
There is currently no treatment that can reverse narcolepsy. Treatment with medications is the first line of defence against the debilitating symptoms. However, changes in behaviour are equally important and when combined with drug treatment have helped most people with narcolepsy improve their alertness and enjoy an active lifestyle.
The main goals of treatment are:
- To help patients approach normal alertness while minimising side effects and disruptions to daily activities.
- To help patents develop behavioural strategies that will allow them to live normally and productively.
Remember that the best treatment plan is one that works for each individual patient.
Some examples are:
- A healthy sleep hygiene: involves getting an adequate amount of sleep (eight hours nightly), avoiding caffeine from mid to late afternoon onward, avoiding cigarettes and alcohol, avoiding shift work, exercising regularly (not close to bedtime), not using the bed for any waking or unrelaxing activities (eg watching TV), and establishing a routine time for going to bed and getting up.
- Avoiding substances (e.g. alcohol, illicit drugs) and medications (e.g. sedating anti-histamines) that may worsen sleepiness or interact with medications for narcolepsy.
- Depending on the individual patient, some sleep physicians may recommend several short daily naps (e.g. 15 minutes during noon and early evening) along with drug treatment to help control excessive sleepiness and sleep attacks. Others report that a single, long afternoon nap works well to improve a patient’s alertness.
- Identifying triggers for cataplexy and developing coping strategies.
- Joining a local well-informed support group.
Doctors generally prescribe stimulants to improve alertness and antidepressants to control symptoms of REM intrusion (cataplexy, hypnagogic hallucinations and sleep paralysis).
Common stimulants used in Australia are dexamphetamine and methylphenidate (Ritalin). Some of the most common side effects of stimulants are headache, irritability, nervousness, insomnia, irregular heartbeat, and mood changes. These medications can be used safely and effectively in most patients but are not suitable in patients with high blood pressure or pre-existing cardiac conditions, or who are at risk of developing such. The potential for abuse with these drugs exists. A careful review by a physician is required prior to starting treatment.
A wake-promoting drug, modafinil (Modavigil) is gaining popularity in the USA as the medication of choice for treating excessive daytime sleepiness. It does not act as a stimulant for other body systems and studies have shown that modafinil is effective in improving alertness with few side effects, low abuse potential, and less likelihood of causing difficulty falling asleep at night. However it is very expensive with the Australian government currently allowing subsidy (PBS) only when stimulants are not suitable for the individual patient.
Commonly used antidepressants in Australia for treating cataplexy Venlafaxine (Efexor) a serotonin and noradrenaline reuptake inhibitor and those belonging to the selective serotonin reuptake inhibitor (SSRI) group. Examples of the latter are fluoxetine (Prozac), paroxetine (Aropax), and sertraline (Zoloft). Reported side-effects include overexcitement, anxiety, insomnia, nausea and reduced sexual drive.
What about pregnancy?
A woman with narcolepsy who is pregnant (or is thinking about becoming pregnant) should speak to her physician about the possible effects of her medication on the child.
Some of these medications are unsafe in pregnancy and alternative treatment plan may be needed if falling pregnant. Although the emotional, physical and psychological demands of having a child should be considered, many parents with narcolepsy do have healthy children and manage parenting successfully.
Narcolepsy and driving
The good news is that diagnosed and medically treated patients with narcolepsy appear no more at risk for road accidents than the general public.
The treating physician will need to discuss the issue of driving with each individual patient. Conditional licensing is permitted on a case-by-case basis subject to specialists assessment and ongoing management. The normal rules for driving apply, for example stop-revive-survive, and not driving under influence of alcohol. Please refer to the latest section P108 "Assessing Fitness to Drive for Commercial and Private Vehicle Drivers" Austroads website.