Narcolepsy

What narcolepsy is

Normally, the brain cycles through wakefulness, non-REM sleep and REM (dream) sleep in an orderly way, and REM sleep starts about 90 minutes after falling asleep. In narcolepsy, the switch that keeps us awake and holds REM sleep back is unstable. People drift into sleep during the day and slip into REM sleep within minutes. Pieces of REM sleep, such as the muscle paralysis and dreaming, also intrude into waking life.

Narcolepsy affects about 1 in 2,000 people. It often takes 8 to 15 years to be diagnosed, because sleepiness is mistaken for laziness, depression or poor sleep habits.

Narcolepsy symptoms

Excessive daytime sleepiness

Present in everyone with narcolepsy. People feel persistently drowsy and can fall asleep without warning: in class, during meals, in conversation or while driving. Short naps of 10 to 20 minutes are refreshing, but sleepiness returns within a few hours. Some people have "automatic behaviors", carrying on with a task such as writing while partly asleep, with no memory of it afterward.

Cataplexy

Sudden, brief loss of muscle tone triggered by strong emotion, most often laughter, but also surprise, excitement or anger. It may cause only a sagging jaw, drooping eyelids, slurred speech or a dropped head, or it can make the knees buckle and the person fall. They stay fully conscious and aware. Episodes usually last seconds to 2 minutes. Cataplexy is unique to narcolepsy type 1. In children, it can look like a strange facial expression with the tongue pushing out.

Sleep paralysis

Being unable to move or speak for a few seconds to minutes when falling asleep or waking, while fully aware. It can be frightening but is harmless. It also occurs occasionally in people without narcolepsy.

Hypnagogic and hypnopompic hallucinations

Vivid, often frightening dream-like images, sounds or a sense of a presence in the room, when falling asleep (hypnagogic) or waking (hypnopompic). These are not a sign of mental illness.

Disrupted night sleep

Despite the daytime sleepiness, many people wake up frequently at night. Vivid dreams, acting out dreams (REM sleep behavior disorder) and restless legs are also more common.

Narcolepsy type 1 vs type 2

What causes narcolepsy?

In type 1, about 70,000 neurons in the hypothalamus that make hypocretin (also called orexin), a chemical that keeps us awake, are destroyed. The evidence points to an autoimmune attack in people with a particular immune gene type (HLA-DQB1*06:02), possibly triggered by infections such as strep throat or influenza. A rise in cases after the 2009 H1N1 pandemic and a specific vaccine used in Europe supports this.

Less often, narcolepsy follows damage to the hypothalamus from tumors, injury or multiple sclerosis. The cause of type 2 is usually unknown. Narcolepsy runs in families only slightly, so most people have no affected relatives.

How narcolepsy is diagnosed

1. Sleep history and diary: often for 1 to 2 weeks, and a sleepiness score such as the Epworth Sleepiness Scale.
2. Actigraphy: a wrist device that confirms you are getting enough sleep before testing.
3. Overnight polysomnography (PSG): a sleep study that excludes other causes such as obstructive sleep apnea.
4. Multiple sleep latency test (MSLT): the next day, five 20-minute nap opportunities, 2 hours apart. Narcolepsy is supported when you fall asleep in 8 minutes or less on average and enter REM sleep in at least two naps.
5. Spinal fluid hypocretin test: occasionally used, especially when the MSLT is unclear or medicines interfere. A low level confirms type 1.

Some antidepressants and stimulants affect the results, so doctors may ask you to stop them for a couple of weeks before testing.

Conditions that look similar

• Not enough sleep, or shift work and circadian rhythm disorders
• Sleep apnea
• Idiopathic hypersomnia: long, unrefreshing sleep without the REM features
• Depression and sedating medicines
• Seizures, which cataplexy is sometimes mistaken for

Narcolepsy treatment

Lifestyle measures

• Two or three scheduled naps of 15 to 20 minutes a day
• Regular bed and wake times, and enough night sleep
• Avoid alcohol and heavy meals during the day
• Regular exercise
• Do not drive when sleepy. Many states have rules for drivers with sleep disorders, so discuss this with your doctor

Medicines

• Wake-promoting drugs: modafinil, armodafinil, solriamfetol and pitolisant.
• Stimulants: methylphenidate or amphetamines when others do not work well enough.
• Oxybates: sodium oxybate and lower-sodium oxybate, taken at night, improve sleepiness, cataplexy and night sleep.
• For cataplexy: pitolisant, oxybates, or certain antidepressants (venlafaxine, some SSRIs) that suppress REM sleep.

Some of these medicines interact with hormonal contraceptives and other drugs, and dose choice must be made with a sleep specialist.

School and work

Students may be eligible for accommodations such as scheduled naps, extra time on tests and recorded lectures. At work, flexible hours and short breaks help. In the US, narcolepsy can qualify for protections under the Americans with Disabilities Act.

Living with narcolepsy

Narcolepsy is lifelong but does not shorten life. With treatment, most people work, study, drive safely and have families. Depression, anxiety and weight gain are more common and should be screened for and treated. Support groups help people explain the condition to friends, employers and teachers.

Frequently asked questions

What are the first signs of narcolepsy?

Excessive daytime sleepiness is usually the first symptom, often in the teens or twenties. People fall asleep in class, at work or in conversation despite a full night's sleep. Cataplexy, sleep paralysis and vivid hallucinations may appear at the same time or years later.

What does cataplexy feel like?

It feels like your muscles suddenly go slack while you remain fully awake. Typically a laugh, joke or surprise makes the knees buckle, the jaw drop or the head nod. It lasts seconds to a couple of minutes and then passes completely. It is harmless in itself but can cause falls.

Can narcolepsy be cured?

Not yet. Narcolepsy is lifelong, but symptoms can usually be controlled well with medicines, scheduled naps and good sleep habits. Research into drugs that mimic hypocretin (orexin agonists) is promising for type 1 narcolepsy in the future.

What is the difference between narcolepsy and just being tired?

Ordinary tiredness improves after a good night's sleep or a few days of rest. Narcolepsy causes sleepiness every day despite adequate sleep, with sudden irresistible urges to nap. REM sleep features, such as cataplexy, sleep paralysis and dream-like hallucinations, are another distinguishing clue.

Can you drive with narcolepsy?

Many people drive safely once symptoms are well controlled with treatment. Do not drive if you feel sleepy, take a short nap before long drives and take regular breaks. Rules vary by state and country, so ask your sleep specialist what applies to you.