Narcolepsy: a primer

• A. A condition causing constant insomnia that prevents any sleep at night
• B. A chronic neurological disorder that disrupts the brain's regulation of sleep-wake cycles
• C. A temporary sleep disruption caused only by jet lag or shift work
• D. A psychological fear of falling asleep at night

• A. Excessive daytime sleepiness with sudden, uncontrollable sleep attacks
• B. Severe memory loss lasting several days
• C. Persistent muscle pain that worsens after exercise
• D. Loss of hearing during periods of stress

• A. Hallucinations that occur while falling asleep
• B. Sudden loss of muscle tone triggered by strong emotions such as laughter or surprise
• C. Temporary paralysis that occurs only during deep non-REM sleep
• D. Repeated nighttime waking caused by breathing pauses

• A. About 1 in 100 people
• B. About 1 in 2,000 people
• C. About 1 in 50,000 people
• D. Fewer than 1 in 10 million people

• A. Excessive caffeine consumption over many years
• B. Loss of hypocretin (orexin)-producing neurons in the hypothalamus
• C. A tumor in the frontal lobe of the brain
• D. Chronic vitamin D deficiency

• A. Presence of excessive daytime sleepiness
• B. Presence of cataplexy (sudden loss of muscle tone triggered by emotion) ✓
• C. Onset before the age of 10
• D. Presence of sleep paralysis only

Why: Narcolepsy Type 1 is characterized by cataplexy and/or low cerebrospinal fluid hypocretin (orexin) levels. Narcolepsy Type 2 involves excessive daytime sleepiness without cataplexy, and typically without the hypocretin deficiency.

• A. Narcolepsy Type 1
• B. Secondary narcolepsy
• C. Narcolepsy Type 2 ✓
• D. Idiopathic hypersomnia

Why: Narcolepsy Type 2 is defined by the absence of cataplexy and normal or only mildly reduced hypocretin levels, while still meeting criteria for excessive daytime sleepiness confirmed by testing such as the MSLT.

• A. Narcolepsy with hypocretin deficiency
• B. Narcolepsy due to a medical condition ✓
• C. Narcolepsy without sleepiness
• D. Sleep-onset narcolepsy

Why: Secondary narcolepsy refers to narcolepsy-like symptoms caused by another medical condition, such as brain tumors, stroke, trauma, or certain neurological diseases, rather than an idiopathic cause.

• A. Polysomnography alone
• B. Electroencephalogram (EEG) during wakefulness
• C. Multiple Sleep Latency Test (MSLT) ✓
• D. Actigraphy over one week

Why: The Multiple Sleep Latency Test measures how quickly a person falls asleep in a series of naps during the day. Narcolepsy is typically supported by a mean sleep latency of 8 minutes or less and two or more sleep-onset REM periods.

• A. Excessive daytime sleepiness
• B. Non-restorative sleep
• C. Cataplexy ✓
• D. Automatic behavior

Why: Cataplexy is the hallmark symptom of Narcolepsy Type 1 and is absent in Type 2. Excessive daytime sleepiness, by contrast, is required for both types of narcolepsy diagnosis.

• A. Frequent nighttime awakenings caused by pain
• B. Excessive daytime sleepiness with sudden sleep attacks
• C. Difficulty falling asleep at night due to racing thoughts
• D. Loud snoring with pauses in breathing during sleep

• A. Waking up unable to move while falling asleep
• B. Sudden loss of muscle tone triggered by strong emotions such as laughter or surprise
• C. Vivid dreaming that occurs during the early stages of sleep
• D. Involuntary movements of the legs during rest

• A. A temporary inability to move or speak while falling asleep or waking up
• B. A complete loss of consciousness lasting several hours
• C. Permanent weakness in the arms after a long nap
• D. Inability to fall asleep despite feeling exhausted

• A. It causes only mild tiredness that is easily relieved by caffeine
• B. It can impair work, school performance, driving safety, and social activities due to unpredictable sleepiness
• C. It mainly affects sleep at night without any daytime effects
• D. It usually disappears entirely after childhood with no lasting impact

• A. Because narcolepsy causes the body to produce excess melatonin
• B. Because the brain's sleep-wake regulation is disrupted, leading to frequent awakenings and poor sleep quality at night
• C. Because narcolepsy only affects the morning hours
• D. Because people with narcolepsy always sleep too long at night

• A. Dopaminergic neurons in the substantia nigra
• B. Hypocretin (orexin)-producing neurons in the lateral hypothalamus ✓
• C. Serotonergic neurons in the raphe nuclei
• D. Cholinergic neurons in the basal forebrain

Why: In narcolepsy type 1, the hypocretin (orexin)-producing neurons of the lateral hypothalamus are lost or severely reduced, leading to low hypocretin levels in the cerebrospinal fluid. Hypocretin helps stabilize wakefulness, so its loss contributes to excessive daytime sleepiness and sudden REM sleep intrusions.

• A. GABA-only signaling in the thalamus
• B. Glutamate signaling in the cerebellum
• C. Wake-promoting monoaminergic and cholinergic systems that hypocretin normally activates ✓
• D. Melatonin release from the pineal gland

Why: Hypocretin neurons project widely to monoaminergic nuclei such as the locus coeruleus (norepinephrine), raphe nuclei (serotonin), tuberomammillary nucleus (histamine), and cholinergic areas. Hypocretin excites these wake-promoting systems, so its loss weakens the brain's ability to maintain alertness.

• A. Inflammation of the spinal cord
• B. Intrusion of REM sleep features, such as muscle atonia, into waking ✓
• C. Overproduction of adrenaline during stress
• D. Damage to the cerebellum affecting coordination

Why: Cataplexy is thought to result from inappropriate activation of the brainstem circuits that produce REM sleep muscle atonia while the person is awake. Emotions like laughter or surprise can trigger this intrusion, causing brief, sudden muscle weakness without loss of consciousness.

• A. A mutation in the dopamine transporter gene
• B. The HLA-DQB1*06:02 allele in the immune system ✓
• C. A deletion in the melatonin receptor gene
• D. A variant in the huntingtin gene

Why: The HLA-DQB1*06:02 allele is strongly linked to narcolepsy type 1, present in the vast majority of affected people. Although carrying the gene is common in the general population, it greatly increases risk, suggesting an autoimmune process may contribute to destruction of hypocretin neurons.

• A. Their brains skip the non-REM stages entirely due to hypocretin loss, so REM sleep can begin abnormally early ✓
• B. They have too much melatonin, which forces REM sleep to occur first
• C. Their hearing is impaired, causing them to wake in non-REM sleep
• D. Their circadian clock runs slower, delaying all sleep stages

Why: Normally, REM sleep occurs about 90 minutes after falling asleep, following non-REM stages. In narcolepsy, the normal regulation of sleep stage transitions is disrupted, so REM sleep can enter almost immediately at sleep onset, called sleep-onset REM periods. This is a useful clue in diagnosis.

• A. Multiple Sleep Latency Test (MSLT)
• B. Polysomnography (PSG) ✓
• C. Actigraphy
• D. Home pulse oximetry

Why: Polysomnography records brain waves, eye movements, muscle tone, breathing, and heart rhythm overnight. It is performed first to rule out other causes of daytime sleepiness, such as obstructive sleep apnea, and to check for abnormally early REM sleep onset. The MSLT is done afterward, the following day.

• A. The total amount of sleep obtained during the night
• B. How quickly a person falls asleep during a series of scheduled daytime nap opportunities ✓
• C. The number of breathing interruptions per hour
• D. The depth of slow-wave sleep during the night

Why: The MSLT typically consists of about four to five nap opportunities spaced two hours apart. Average sleep latency under about 8 minutes, along with two or more sleep-onset REM periods, supports a diagnosis of narcolepsy.

• A. Frequent nighttime awakenings
• B. Low cerebrospinal fluid hypocretin-1 (orexin) levels ✓
• C. Elevated thyroid-stimulating hormone
• D. Reduced iron stores on blood testing

Why: Low cerebrospinal fluid hypocretin-1 (orexin), typically at or below about one-third of normal, is a highly specific biomarker for narcolepsy type 1, which involves cataplexy. It reflects loss of hypocretin-producing neurons in the hypothalamus.

• A. To measure brain wave activity during REM sleep
• B. To document sleep-wake patterns over one to two weeks and confirm that sleep disruption is not due to poor sleep hygiene or an irregular schedule ✓
• C. To directly diagnose cataplexy episodes
• D. To replace the need for polysomnography

Why: A sleep diary and actigraphy show the patient's usual sleep-wake pattern over time. This helps confirm adequate nighttime sleep before testing, which is important because insufficient sleep can mimic narcolepsy on the MSLT and lead to a false-positive result.

• A. Fasting for 12 hours
• B. Avoiding sedating medications and ensuring adequate prior nighttime sleep ✓
• C. Taking a stimulant medication one hour before testing
• D. Exercising vigorously the morning of the test

Why: Sedating medications and insufficient prior sleep can shorten sleep latency and produce misleading results. Clinicians typically ask patients to stop these medications beforehand and confirm adequate sleep, usually verified by the preceding polysomnogram, so that the MSLT accurately reflects sleepiness.

• A. Benzodiazepines
• B. Stimulants such as methylphenidate or amphetamine-based medications ✓
• C. Antipsychotics
• D. Opioid analgesics

Why: Stimulants are a mainstay for treating excessive daytime sleepiness in narcolepsy. Modafinil and armodafinil are also commonly used first-line wakefulness-promoting agents. Benzodiazepines and opioids tend to worsen sleep fragmentation and are not appropriate for this purpose.

• A. Donepezil
• B. Levothyroxine
• C. Sodium oxybate (gamma-hydroxybutyrate) ✓
• D. Metformin

Why: Sodium oxybate is one of the most effective treatments for cataplexy and also helps consolidate nighttime sleep and reduce daytime sleepiness. Antidepressants such as venlafaxine are also used off-label for cataplexy. The other options are not standard narcolepsy treatments.

• A. To prevent morning headaches caused by caffeine withdrawal
• B. To consolidate nighttime sleep and reduce nocturnal awakenings in people with narcolepsy ✓
• C. Because the drug must be taken with food to be absorbed
• D. To avoid interactions with stimulant medications taken in the morning

Why: The two-dose schedule is designed to reduce fragmented nighttime sleep, which is a common feature of narcolepsy, while also improving daytime alertness and reducing cataplexy. Taking the second dose too late can cause excessive sedation, so timing is important.

• A. Avoiding all daytime naps
• B. Scheduled short naps and consistent sleep-wake routines ✓
• C. Sleeping in a completely dark room with no fixed bedtime
• D. Extended fasting between meals

Why: Planned short daytime naps (often 15 to 20 minutes) can provide refreshment, and consistent sleep schedules help stabilize the sleep-wake cycle. Avoiding naps is counterproductive for people with narcolepsy, since their sleepiness is a neurological problem rather than a simple sleep debt issue.

• A. Narcolepsy is completely cured by a single medication taken once.
• B. Treatment aims to manage symptoms, since narcolepsy is a lifelong neurological condition without a cure. ✓
• C. Treatment is unnecessary because excessive daytime sleepiness resolves on its own.
• D. Only children with narcolepsy require medication, while adults do not.

Why: Narcolepsy has no cure. Treatment focuses on symptom control, including excessive daytime sleepiness, cataplexy, and disrupted nighttime sleep, and typically continues throughout life. Medication needs are individualized and apply across ages.

• A. Chronic insomnia lasting more than three months
• B. Cataplexy, a sudden loss of muscle tone triggered by strong emotions ✓
• C. Loud snoring with frequent awakenings
• D. Restless legs that worsen at night

Why: Cataplexy, a sudden loss of muscle tone often triggered by laughter, surprise, or other strong emotions, is a hallmark of narcolepsy type 1. Insomnia, snoring, and restless legs are not core features of the condition.

• A. Sleeping in as late as possible each morning
• B. Avoiding all naps during the day
• C. Scheduling short, planned naps at consistent times ✓
• D. Drinking alcohol in the evening to deepen nighttime sleep

Why: Short, scheduled naps (often 15 to 20 minutes) can provide refreshment and help manage sleepiness. Avoiding naps usually increases sleepiness, and alcohol fragments sleep, worsening daytime symptoms.

• A. It eliminates the need for any medication
• B. It helps stabilize the sleep-wake cycle and can reduce daytime sleepiness ✓
• C. It prevents cataplexy episodes entirely
• D. It replaces the need for a medical diagnosis

Why: Maintaining a regular bedtime and wake time, with adequate nighttime sleep, helps stabilize the sleep-wake cycle and can reduce excessive daytime sleepiness. It supports treatment but does not cure narcolepsy or fully prevent cataplexy.

• A. Being required to work only night shifts without breaks
• B. Flexible scheduling and permission for brief rest breaks ✓
• C. Removing all physical activity from their daily routine
• D. Avoiding any tasks that require concentration

Why: Flexible scheduling and allowing brief rest breaks accommodate the unpredictable sleepiness of narcolepsy and help people stay productive and safe. The other options would increase fatigue or are not appropriate accommodations.

• A. Driving only when feeling fully rested and avoiding drowsy driving ✓
• B. Operating heavy machinery while taking sedating medications without checking with a doctor
• C. Swimming alone without any supervision during sleepy periods
• D. Skipping meals to stay alert

Why: Excessive sleepiness and sudden sleep attacks can make driving dangerous, so people with narcolepsy should avoid driving when drowsy and follow medical advice about safety. Skipping meals and unsupervised activities increase risk rather than reducing it.