Hypersomnia and narcolepsy are both sleep disorders that make people very tired during the day. Because of this shared symptom — excessive daytime sleepiness (EDS) — they’re often mistaken for each other. Even scientists have said that certain types of narcolepsy look very similar to hypersomnia on some tests.

Even scientists have said 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 extremely 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. However, the combination of symptoms that often point to idiopathic hypersomnia includes:

• Sleeping at least 10 to 11 hours a night
• Experiencing nonrestorative sleep (not feeling completely rested after sleeping)
• Feeling 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 the cause of each disorder.

Researchers don’t yet know exactly what causes idiopathic hypersomnia. It’s known to be a disorder of the nervous system, but scientists are still investigating exactly how it develops.

Some people diagnosed with idiopathic hypersomnia overproduce a 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 a key chemical released by nerves that promotes sleep.

Beyond that, researchers don’t know what causes idiopathic hypersomnia. However, certain genes may increase a person’s risk of developing this condition.

What Is Narcolepsy?

Like idiopathic hypersomnia, narcolepsy is a sleep disorder.

People diagnosed with narcolepsy (and idiopathic hypersomnia) have 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.

Narcolepsy interrupts the sleep-wake cycle. For that reason, people with this diagnosis may also have trouble sleeping throughout the night.

Narcolepsy Symptoms

The characteristic symptoms of narcolepsy include:

• Excessive daytime sleepiness, often suddenly
• Disrupted nighttime sleep
• Changes in rapid eye movement (REM) sleep patterns. People diagnosed with narcolepsy often move into REM sleep much faster than typical 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 linked to 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 involve seeing, hearing, or otherwise experiencing sights, sounds, or sensations that aren’t really there. Some people with narcolepsy may hallucinate when they fall asleep or wake up. These hallucinations happen when parts of REM sleep, like dreaming, mix with being awake, almost like the brain is dreaming while the person is still conscious.

Other Symptoms

Narcolepsy may be linked with symptoms unrelated to sleep, such as obesity (having a higher body weight) and early puberty.

Causes of Narcolepsy

Type 1 narcolepsy is linked to low levels of hypocretin. A part of the brain called the hypothalamus uses this chemical messenger to help the brain stay awake. In people diagnosed with narcolepsy, neurons containing hypocretin degenerate and die. When these brain cells die, it makes people feel less alert and causes unusual REM sleep, which is linked to narcolepsy. Researchers believe that an autoimmune process may cause these cells to degenerate.

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 is still unknown.

Diagnosing Idiopathic Hypersomnia and Narcolepsy

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

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

The diagnosis process is similar for narcolepsy and idiopathic hypersomnia, involving such steps as sleep logs and diagnostic testing.

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 tracks your movements to help show how much sleep you’re getting and how restful it is.

Testing for Idiopathic Hypersomnia and Narcolepsy

Doctors use certain tests to collect data about sleep to diagnose hypersomnia or narcolepsy. These tests help show how quickly someone falls asleep and how often they enter REM sleep during naps.

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 the REM stage.

Lumbar Puncture

A spinal tap may be performed to measure your hypocretin level in the spinal fluid. Low levels of hypocretin can be a strong sign of narcolepsy, especially type 1.

Differential Diagnosis

Even though the testing process is similar, whether you’re diagnosed with idiopathic hypersomnia or narcolepsy depends on the specific symptoms you have.

People with idiopathic hypersomnia usually show:

• Long sleep times
• Severe trouble waking up
• Extreme (but resistible) sleepiness
• No hallucinations, cataplexy, or sleep paralysis
• No unusual REM sleep patterns

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
• Multiple 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. This allows them to recommend or prescribe the proper treatments.

Treatment of Idiopathic Hypersomnia and Narcolepsy

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

Medications for 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.

With that in mind, let’s look at treatments aimed at promoting wakefulness and reducing daytime sleepiness. Treatment for both conditions aims 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 combat excessive sleepiness for people with narcolepsy and other sleep disorders, but may not work as well for idiopathic hypersomnia.
• An oral solution of calcium, magnesium, potassium, and sodium oxybates could previously only treat narcolepsy, but was FDA-approved for idiopathic hypersomnia in 2021.
• Sodium oxybate treatments are approved for the treatment of EDS and cataplexy in people with narcolepsy. They may be recommended for idiopathic hypersomnia in some cases.
• Histamine type 3 (H3) receptor antagonist/inverse agonist can treat excessive daytime sleepiness associated with narcolepsy. They’re also helpful in controlling cataplexy symptoms. In some cases, they may also be tried for treating idiopathic hypersomnia.
• Wakefulness-promoting agents that aren’t stimulants can improve 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.
• Specific antibiotics may reduce GABA in the brain to treat idiopathic hypersomnia.
• Benzodiazepine antagonists may also treat some cases of idiopathic hypersomnia by reducing GABA.

Clinical trials for sleep disorders (studies that test the safety and effectiveness of drugs in people) are investigating the role of other medications in narcolepsy. This includes the antidepressant reboxetine (an antidepressant that has been approved in Europe but not the U.S.) and orexin agonists (compounds used for neurological and psychiatric disorders).

Nonmedical Treatments for Idiopathic Hypersomnia and Narcolepsy

Some treatments for excessive daytime sleepiness don’t involve taking medications. These options can include sleep hygiene, cognitive behavioral therapy (CBT), and scheduled naps.

Some treatments for excessive daytime sleepiness don’t involve taking medications.

Sleep Hygiene

Improving sleep hygiene may help people optimize their sleep. This includes habits like turning in at the same time every night, avoiding blue light before bed, and not consuming caffeine, alcohol, or other medications that interfere with sleep. This is an excellent way to manage idiopathic hypersomnia or narcolepsy at home.

Cognitive Behavioral Therapy

Many sleep medicine specialists recommend 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 may help people manage some of the challenges that may accompany sleep disorders, such as their effects on mood and daily life.

Scheduled Naps

Scheduled naps can help people with narcolepsy stay alert and avoid falling asleep unexpectedly. Taking short, planned naps during the day can also improve mood and focus.

The Bottom Line

If you’re feeling very tired all the time, even after a full night’s sleep, talk to a sleep doctor. Getting the right diagnosis is the first step to feeling better and having more energy for school, work, family, and daily life. With the right treatment, many people start to feel more awake and able to enjoy their day.

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