What Tests Are Used to Diagnose Narcolepsy?

Narcolepsy is a neurological condition that causes excessive daytime sleepiness despite otherwise getting enough sleep. It also may affect your quality of sleep. It happens when your brain has difficulty controlling your sleep-wake cycles.

Generally, adult individuals fall into the REM state of sleep in 60 to 90 minutes. The REM state of sleep is sleep stage that allows you to dream. During REM, your brain keeps your muscles limp to stop your body from responding to your dreams.

People with narcolepsy often enter REM within 15 minutes of falling asleep and can even experience the dreams and muscle weakness of REM sleep during waking hours.

Narcolepsy makes you feel very tired throughout the day. You might even fall asleep in the middle of an activity such as talking or driving. Other symptoms include:

• sudden muscle weakness (called cataplexy)
• hallucinations
• sleep paralysis

Even when daytime symptoms are mild, it’s important to talk with a medical profession if you think you might have narcolepsy.

Getting a good night’s rest is one of the most important things you can do for your health. Frequently interrupted sleep, like the disrupted sleep-wake cycle in narcolepsy, can lead to long-term effects on your overall health and wellness.

Your first step in a narcolepsy diagnosis is often a visit to your primary care doctor.

They’ll go over your medical history to rule out other possible causes of excessive daytime fatigue despite getting an adequate amount of sleep, such as sleep apnea, medical disorders, depression, or a medication you’re taking. Your doctor will then refer you to a sleep specialist.

The sleep specialist will go over your medical history. If they think it’s likely you have narcolepsy, they’ll recommend two separate sleep studies.

The first sleep study, called a polysomnogram, is a test that measures your quality of sleep. The second test is a multiple sleep latency test (MSLT), which will measure how quickly you fall asleep and when you enter the REM phase of sleep.

You’ll need to stop taking certain medications, such as stimulants and antidepressants, in the weeks before the sleep studies. Your sleep specialist will let you know which medications to stop taking and when to stop taking them.

It’s also important to let your sleep specialist know your normal schedule so that your tests can be scheduled at the best time. For example, if you normally work overnight and sleep during the day, your sleep study may be held during daytime hours.

Polysomnogram narcolepsy test

A sleep study requires that you sleep in a lab overnight. The sleep lab might be in a hospital or medical clinic.

When you arrive, you’ll have electrodes placed on your scalp, chin, and outer eyelids. These electrodes will let the polysomnogram measure signals to know whether you’re awake or asleep. They can also detect REM sleep.

You’ll also have breathing and heart monitors hooked up so that your heart rate and respiration can be observed. A sleep technician will monitor you throughout the test.

The polysomnogram will look for brain signals that indicate narcolepsy. This might include

• waking up suddenly
• rapid falling into REM sleep
• reduced sleep efficiency

It can also detect other, more common, sleep-distorting conditions, such as sleep apnea.

Multiple sleep latency test

An MLST is performed during the day. This test is sometimes called a “nap study.” During the study, you’ll be given the chance to nap every 2 hours. You’ll have four or five nap opportunities over the course of the study.

An MLST is looking for how quickly you fall asleep and when your sleep becomes REM sleep. People with narcolepsy often fall asleep in about 8 minutes or less and generally go into REM sleep during at least 2 of the MSLT naps.

Other narcolepsy tests

The polysomnogram and MSLT are usually enough to diagnose or rule out narcolepsy for many people. However, other tests might be needed in some cases.

One uncommon additional test is a measurement of a neurotransmitter called hypocretin (also called orexin) in the cerebrospinal fluid.

Cerebrospinal fluid is sampled through a procedure called a lumbar puncture. During this test, a needle is inserted into your spine so that a sample of cerebrospinal fluid can be taken. People with narcolepsy type 1 often have low levels of hypocretin in their cerebrospinal fluid.

The results of your test and your symptoms will be examined to diagnose narcolepsy. If the results are positive, you’ll be diagnosed with either type 1 or type 2 narcolepsy. Both types of narcolepsy cause daytime sleepiness and may disrupt your sleep-wake cycle, but there are some differences between the two.

• Narcolepsy type 1. To be diagnosed with narcolepsy type 1, you need to meet one of two qualifiers — your narcolepsy must either cause you to lose muscle tone and cause muscle weakness during the day, or it must be connected to a low level of hypocretin in your cerebrospinal fluid.
• Narcolepsy type 2. Narcolepsy type 2 is diagnosed if you don’t have daytime muscle weakness or a low level of hypocretin.

Treatments

There is no cure for either type of narcolepsy, but there are some medications and lifestyle changes that can help.

Your treatment plan will depend on your type of narcolepsy, the severity, and your overall health. It might take some trial and error for you and your sleep physician to find a treatment that works for you.

Options for narcolepsy treatment include:

• Wake-promoting medications. These medications can help you stay awake during the day. People with narcolepsy are often prescribed modafinil or armodafinil as a first-line treatment. More traditional stimulants, such as amphetamines, might be prescribed if these don’t help. Newer medications such as pitolisant or solriamfetol may also be considered
• Antidepressants. Certain antidepressants can help with hallucinations, sleep paralysis, and muscle weakness.
• Oxybates. Sodium oxybate both reduces daytime sleepiness and combats muscle weakness. This medication is taken at night in divided doses.
• Sleep schedule adjustments. It’s important for people with narcolepsy to achieve an adequate amount of nightly sleep and to keep a consistent sleep schedule. Your doctor might also advise that you take scheduled short naps throughout the day.
• Dietary changes. Avoiding caffeine, alcohol, and large meals in the hours leading up to your scheduled bedtime can improve sleep quality. It is important to avoid other medications that may cause daytimes drowsiness or nighttime insomnia or interact with narcolepsy medications.
• Lifestyle changes. In addition to adequate sleep at night and naps in the day with good sleep-wake routines, adjustment in work or school schedules may need to be considered.

Narcolepsy disrupts your sleep-wake cycle. It can leave you feeling tired throughout the day and even cause you to fall asleep during daily activities. You might also have symptoms like hallucinations, daytime muscle weakness, and sleep paralysis.

The first step to getting treatment for narcolepsy is getting a diagnosis. A narcolepsy diagnosis requires sleep studies performed in a specialized sleep center or lab.

There is no cure for narcolepsy, but treatments can help you manage your symptoms and regain your energy.