Hypersomnia and narcolepsy are sleep disorders. The two are often mistaken for each other because they’re characterized by the same main symptom: excessive daytime sleepiness (EDS). Even scientists have noted that certain types of narcolepsy look very similar to hypersomnia on some tests.

Despite their similarities, the two are different disorders. They have different symptoms and causes, and they’re sometimes treated differently.

Understanding the differences between hypersomnia and narcolepsy can help you receive the correct diagnosis and treatment.

What Is Hypersomnia?

Hypersomnia means too much sleep. This sleep disorder can cause people to sleep too long and be excessively tired during the day.

There are several types of hypersomnia. Idiopathic hypersomnia is a form that isn’t related to any other condition or caused by medication. Idiopathic hypersomnia is the type of hypersomnia most often confused with narcolepsy.

Idiopathic Hypersomnia Symptoms

EDS occurs with both idiopathic hypersomnia and narcolepsy, but symptoms unique to idiopathic hypersomnia include:

• Sleeping at least 10 to 11 hours a night
• Excessive daytime sleepiness, even with extended sleep times

Although these are the only two symptoms required for a diagnosis of idiopathic hypersomnia, many people with the disorder also experience:

• Nonrestorative sleep (not feeling completely rested after sleeping)
• Extreme grogginess or disorientation upon waking
• Taking an excessive amount of time to wake up
• Falling asleep at inappropriate times

Causes of Idiopathic Hypersomnia

One of the major differences between narcolepsy and hypersomnia is what causes each disorder.

Researchers don’t yet know exactly what causes idiopathic hypersomnia. It’s known to be a disorder of the nervous system, but the exact way idiopathic hypersomnia develops is still being investigated.

Some people diagnosed with idiopathic hypersomnia have been found to overproduce a particular substance that acts on the brain like a sleeping pill or pain reducer. People whose bodies make too much of this substance have enhanced gamma-aminobutyric acid (GABA) activity in the brain. GABA is the key chemical released by nerves that promotes sleep.

Beyond that, researchers don’t know what causes idiopathic hypersomnia, though a few genes may play a role in passing down the condition between generations.

What Is Narcolepsy?

Like idiopathic hypersomnia, narcolepsy is a sleep disorder.

People diagnosed with narcolepsy (and idiopathic hypersomnia) exhibit excessive daytime sleepiness. They may struggle to stay awake consistently throughout the day — when the urge to sleep hits, it’s nearly impossible to resist. In fact, people with narcolepsy often fall asleep at unexpected times or in unusual places or positions.

Because narcolepsy interrupts the sleep-wake cycle, people with this diagnosis may also have trouble sleeping throughout the night.

Narcolepsy Symptoms

The characteristic symptoms of narcolepsy include:

• Excessive daytime sleepiness, often with sudden onset
• Disrupted nighttime sleep
• Changes in rapid eye movement (REM) sleep patterns. People diagnosed with narcolepsy often move into REM sleep much faster than normal sleepers.

Some people with a narcolepsy diagnosis may also experience other symptoms.

Cataplexy

Cataplexy refers to a sudden loss of muscle tone. People with cataplexy may slur their speech, fall over, or experience other muscular symptoms. This loss of muscle tone is also usually associated with feeling a strong emotion, either positive or negative.

Narcolepsy with cataplexy is called type 1 narcolepsy. Type 2 narcolepsy doesn’t include cataplexy.

Sleep Paralysis

Narcolepsy is often accompanied by sleep paralysis — a temporary inability to speak or move when falling asleep or waking up. These episodes mimic the paralysis that normally occurs only during REM sleep.

Sleep Hallucinations

Hallucinations — seeing, hearing, or otherwise experiencing things that aren’t there — can occur upon falling asleep and awakening in people with narcolepsy. These hallucinations seem to be tied to experiences that usually occur during REM sleep being inappropriately combined with a waking brain.

Other Symptoms

Narcolepsy type 1 may be associated with symptoms unrelated to sleep, such as obesity (having a higher body weight) and early onset of puberty.

Causes of Narcolepsy

Type 1 narcolepsy is linked to low levels of hypocretin, a chemical messenger that the hypothalamus (a part of the brain) uses to help the brain stay awake. In people diagnosed with narcolepsy, neurons containing hypocretin degenerate and die. The death of these neurons reduces a person’s alertness and can cause the unusual REM cycles linked with narcolepsy. Researchers believe that an autoimmune process may cause the degeneration of these cells.

There’s some evidence that narcolepsy can be genetic (inherited). However, the chances of passing it on seem to be around 1 percent. The cause of type 2 narcolepsy remains unknown.

Diagnosing Idiopathic Hypersomnia and Narcolepsy

The process of diagnosing both narcolepsy and idiopathic hypersomnia is the same.

Diagnosis usually begins with a visit to the doctor. The doctor will start by asking about your recent sleep history, as well as any symptoms you’re experiencing during the day or at night.

Most sleep medicine specialists also require people to keep a log of their sleep for a week or two and maybe wear an actigraph. This device monitors sleep/wake cycles to collect data. It measures your movement, which can indicate the amount and quality of your sleep.

Testing for Idiopathic Hypersomnia and Narcolepsy

Doctors use certain tests to collect data about sleep to diagnose hypersomnia or narcolepsy.

Polysomnography

For this test, you’ll stay overnight at a sleep laboratory and sleep with electrodes attached to your scalp. The test looks at the activity of your brain, heart, muscles, eyes, and lungs during the night.

Multiple Sleep Latency Test

A multiple sleep latency test (MSLT) is also conducted at a lab but takes place during the day. It should be performed the day after the polysomnogram.

During an MSLT, you’ll be required to take four or five naps spaced two hours apart. Sleep specialists will measure how long it takes you to fall asleep and how fast you enter into the REM stage.

Lumbar Puncture

A spinal tap may be performed to measure your hypocretin level in the spinal fluid.

Differential Diagnosis

Although the process of diagnosis is similar, receiving a diagnosis of idiopathic hypersomnia or narcolepsy depends on the characteristics of your symptoms.

People with idiopathic hypersomnia usually show:

• Long sleep times
• Severe trouble waking up
• Extreme (but resistible) sleepiness
• No hallucinations, cataplexy, or sleep paralysis
• No extraordinary REM cycle behavior
• People who receive a diagnosis of narcolepsy often show:
• Shorter, more frequent sleep times
• Insomnia when they should be sleeping (at night)
• Extreme (often irresistible) daytime sleepiness
• Hallucinations
• Cataplexy
• Sleep paralysis
• More than two sleep-onset REM periods during lab sleep testing

Using your self-reported symptoms and diagnostic testing, your doctor will be able to determine which sleep disorder you have, allowing them to recommend or prescribe the proper treatments.

Treatment of Idiopathic Hypersomnia and Narcolepsy

Some of the treatments for idiopathic hypersomnia and narcolepsy overlap, although a few are reserved for narcolepsy alone.

Treatments for Both Idiopathic Hypersomnia and Narcolepsy

Most medications given to treat idiopathic hypersomnia are used off-label. This means that the medications haven’t necessarily been tested extensively on people diagnosed with idiopathic hypersomnia, in particular.

With that in mind, read on to learn about treatments for idiopathic hypersomnia and narcolepsy. The aim of treatment for both diseases is to promote wakefulness and reduce daytime sleepiness. In narcolepsy with cataplexy, specific drugs may be used to help control sudden loss of muscle tone.

Stimulant Medications

Both modafinil (Provigil) and armodafinil (Nuvigil) are stimulants that help combat excessive daytime sleepiness. These medications are specifically indicated to improve wakefulness in people with obstructive sleep apnea/hypopnea syndrome, narcolepsy, and shift work sleep disorder. When taking these medications, it’s important to watch for side effects like dizziness, headaches, and nausea.

Modafinil and armodafinil may not be as effective for people diagnosed with idiopathic hypersomnia as they are for those diagnosed with narcolepsy.

Other forms of stimulants, including methylphenidate transdermal patch (Daytrana) and dextroamphetamine (Dexedrine), can also be used to help fight excessive daytime sleepiness. Despite being a different class of stimulant, they may have side effects similar to those sometimes caused by modafinil and armodafinil.

Other Medications

In 2021, the U.S. Food and Drug Administration (FDA) approved the brand-name drug Xywav — an oral solution of calcium, magnesium, potassium, and sodium oxybates — to treat people with idiopathic hypersomnia. This medication, the first approved specifically for idiopathic hypersomnia, helps people stay awake and feel less tired by improving their sleep at night. Previously, it was approved for treating narcolepsy.

Other medications that may be tried in idiopathic hypersomnia include clarithromycin and flumazenil, as well as two narcolepsy drugs discussed below — sodium oxybate (Xyrem) and pitolisant (Wakix).

Sleep Hygiene

Improving sleep hygiene through practices like turning in at the same time every night, avoiding blue light before bed, and not consuming substances that interfere with sleep (like caffeine, alcohol, or other medications) may help people optimize their sleep.

Cognitive Behavioral Therapy

Many sleep medicine specialists recommend cognitive behavioral therapy (CBT) for both idiopathic hypersomnia and narcolepsy. CBT won’t treat the condition and can’t replace medications prescribed for narcolepsy or idiopathic hypersomnia, but it can help people manage some of the challenges that may accompany sleep disorders, such as their effects on mood and daily life.

Treatments for Narcolepsy

In addition to the treatments listed above, some may be used for narcolepsy in particular. These medications include the following:

• Sodium oxybate is FDA-approved to treat type 1 narcolepsy, with an effect on cataplexy. This drug also comes in an extended-release formulation (Lumryz).
• Pitolisant is approved to treat excessive daytime sleepiness associated with narcolepsy. It’s also helpful to control cataplexy symptoms.
• Solriamfetol (Sunosi) is approved to treat daytime sleepiness associated with narcolepsy or obstructive sleep apnea.
• Antidepressants can be used to help ease the symptoms of cataplexy, hallucinations, and sleep paralysis by suppressing REM sleep.

Clinical trials (studies that test the safety and effectiveness of drugs in people) are investigating the role of other medications in narcolepsy, such as the antidepressant reboxetine and orexin agonists (compounds used for neurological and psychiatric disorders).

Scheduled Naps

People with narcolepsy need to sleep often, so scheduling naps may help them avoid or reduce instances of falling asleep unintentionally.

Find Your Team

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