Narcolepsy: Symptoms, Causes and Treatment

Overview

Narcolepsy is a long-term neurological condition in which the brain cannot properly regulate sleep and wakefulness. People with narcolepsy feel severely sleepy during the day and may fall asleep suddenly, even mid-conversation, while also often sleeping poorly at night.

There are two types. Narcolepsy type 1 includes cataplexy, brief episodes of muscle weakness triggered by strong emotions like laughter or surprise, and is caused by loss of brain cells that produce hypocretin (also called orexin). Narcolepsy type 2 has sleepiness without cataplexy and normal hypocretin levels, and its cause is less clear.

Symptoms usually begin in adolescence or young adulthood, and diagnosis is often delayed for years. There is no cure, but medicines and planned naps can control symptoms well enough for most people to work, study and drive safely.

US studies estimate that narcolepsy affects roughly 1 in 2,000 people, and many cases remain undiagnosed.

Common symptoms

Excessive daytime sleepiness and sudden sleep attacks
Cataplexy: sudden muscle weakness such as knees buckling, jaw sagging or head dropping, triggered by laughter or emotion (type 1)
Sleep paralysis on falling asleep or waking
Vivid, dream-like hallucinations when falling asleep or waking
Disrupted nighttime sleep with frequent awakenings
Automatic behaviours, continuing an activity with no memory of it
Short naps that feel refreshing

Causes and risk factors

Loss of hypocretin-producing neurons in the hypothalamus (type 1), thought to be autoimmune
Genetic susceptibility, particularly the HLA-DQB1*06:02 gene variant
Possible environmental triggers such as certain infections
Rarely, brain injury or tumours affecting the hypothalamus
Family history (a small increased risk)

How it is diagnosed

Diagnosis usually involves an overnight polysomnogram followed the next day by a Multiple Sleep Latency Test (MSLT), in which you take five scheduled nap opportunities. Narcolepsy is supported by a mean sleep latency of 8 minutes or less and two or more sleep-onset REM periods (a REM period on the preceding night's study can count as one).

Type 1 can also be confirmed by a low hypocretin level in cerebrospinal fluid. Before testing, clinicians often ask you to keep a sleep diary or wear an activity tracker for one to two weeks and, where safe, to stop medicines that affect REM sleep, since insufficient sleep and some drugs can distort results.

Treatment options

Wake-promoting medicines

Modafinil and armodafinil are commonly used to reduce sleepiness.

Solriamfetol

A dopamine and norepinephrine reuptake inhibitor approved for excessive sleepiness in narcolepsy.

Pitolisant

A histamine H3 receptor medicine that improves sleepiness and can reduce cataplexy.

Oxybates

Sodium oxybate and lower-sodium or once-nightly formulations taken at night improve sleepiness and cataplexy and are available through restricted programmes.

Stimulants

Methylphenidate or amphetamine-based medicines are used when other options are not enough.

Antidepressants

Certain antidepressants can reduce cataplexy, sleep paralysis and hallucinations.

Scheduled naps

Short planned naps of 15 to 20 minutes can improve alertness.

What you can do yourself

Keep a regular sleep schedule and protect nighttime sleep
Plan short naps during the day
Avoid alcohol and sedating medicines
Do not drive when sleepy, and follow local rules on driving with narcolepsy
Tell teachers or employers about reasonable accommodations
Join a support group to connect with others who have narcolepsy

When to see a doctor

You fall asleep at inappropriate times despite enough sleep
Your knees buckle or face goes slack when you laugh or feel strong emotion
You experience sleep paralysis or hallucinations often
Sleepiness affects your driving, work or schooling

Frequently asked questions

Do people with narcolepsy fall asleep suddenly all the time?

Sudden sleep attacks happen, but the main symptom is constant, heavy sleepiness that can make it hard to stay awake in quiet settings. Most people with narcolepsy do not collapse into sleep without warning many times a day.

What does cataplexy feel like?

Cataplexy is a sudden, brief loss of muscle tone while fully awake, often triggered by laughter, surprise or anger. It can be subtle, like a sagging jaw or drooping eyelids, or cause the knees to buckle. Consciousness is preserved and episodes usually last seconds to a couple of minutes.

Can I drive if I have narcolepsy?

Many people with well-controlled narcolepsy drive safely, but rules vary by country and state. Talk with your clinician, never drive when sleepy, and consider a short nap before driving.

Is narcolepsy inherited?

Most cases are not directly inherited. Having a close relative with narcolepsy raises your risk somewhat, and a common immune system gene variant is linked to type 1, but most people with that variant never develop narcolepsy.

Why do I need to stop some medicines before the MSLT?

Antidepressants and stimulants can change REM sleep and sleep latency and give misleading results. Your clinician will tell you which medicines to taper and when, and you should never stop medicines without their guidance.