Narcolepsy Nerd Alert: Types of Narcolepsy

Why Am I So Tired?

Excessive sleepiness during the daytime even after adequate sleep is called hypersomnolence. People who struggle to stay awake throughout the day may have a central disorder of hypersomnolence, also called a central nervous system (CNS) hypersomnia.

Hypersomnolence could be due to:

• Narcolepsy type 1 (narcolepsy with cataplexy)
• Narcolepsy type 2 (narcolepsy without cataplexy)
• Idiopathic hypersomnia
• An underlying condition that is not a sleep disorder, like lupus, which causes extreme fatigue

Inadequate sleep and sleep deprivation will cause anyone to feel tired during the day, but if you consistently get adequate sleep and still struggle with sleepiness, or if you are regularly unable to sleep despite your best efforts, you may have a sleep disorder, and you should talk to your doctor.

Narcolepsy Symptoms

The Narcolepsy Pentad is typically used to identify narcolepsy:

• Excessive daytime sleepiness (EDS)
• Cataplexy
• Sleep-related hallucinations
• Sleep paralysis
• Disrupted nighttime sleep

Idiopathic Hypersomnia (IH) Symptoms

• Excessive daytime sleepiness (EDS)
• Prolonged sleep time
• Unrefreshing naps
• Sleep inertia
• Difficult sleep-to-wake transition

It’s more than just feeling tired, it feels like someone has nailed something heavy to my face between my eyebrows, and in order to open my eyes I need to lift it with my eyelids.”

– Amy

Diagnostic Tools

Sleep specialists assess sleep-related problems using a variety of tools:

• Symptom history
• Questionnaires
• Daily sleep logs
• Actigraphy

When it comes to diagnosing narcolepsy type 1, type 2, and IH, specific tests are often used:

• The overnight sleep study, called a nocturnal polysomnogram (PSG)
• The multiple sleep latency test (MSLT)
• A blood test for the HLA DQB1*06:02 gene variant
• A cerebrospinal fluid (CSF) orexin test

In terms of advocating for yourself, it is important to know what tests are available. If you’re uncertain about your diagnosis, make sure you’ve engaged your healthcare providers to see if one or more of these tests would be helpful in your situation.”

– Dr. Chad Ruoff

Diagnostic Criteria

The table below summarizes specific criteria used to differentiate narcolepsy type 1, type 2, and idiopathic hypersomnia.

MSLT Challenges

The multiple sleep latency test (MSLT) is the primary way sleep specialists test for narcolepsy type 1, type 2, and idiopathic hypersomnia. However recent research has shown that the MSLT doesn’t consistently differentiate these conditions.

Surprisingly, people in the general population — who don’t have daytime sleepiness — may meet the diagnostic criteria for narcolepsy, leading to false positives. Remember, the current diagnostic criteria for narcolepsy are falling asleep within 8 minutes and having at least two dream periods (SOREMPs) in the five naps during an MSLT.

False negatives are also reported. Many people who do have idiopathic hypersomnia may not have a mean sleep latency that indicates a central disorder of hypersomnolence.

What’s Next?

Sleep researchers believe that the current diagnoses may not accurately categorize people with hypersomnolence based on pathophysiology — the underlying cause of their sleepiness. Changes are expected in the next version of the International Classification of Sleep Disorders (ICSD), and this is part of the process.

Being diagnosed with a chronic illness can significantly affect a person’s life and sense of identity. If a diagnosis changes later, it can be confusing and disruptive. It can be reassuring to know that changes in your diagnosis are not caused by something uniquely difficult about you or your sleepiness.

No matter how your sleepiness is labeled, know that it is valid — your experience is real.

For more information on this topic, download the Types of Narcolepsy toolkit!

Types of Narcolepsy: Listen or Watch!

The Types of Narcolepsy broadcast originally aired on June 29, 2022.

Meet Our Guest

Chad Ruoff, M.D., is an internal medicine physician specializing in sleep medicine. He enjoys evaluating and treating all sleep disorders such as sleep apnea, narcolepsy and idiopathic hypersomnia, restless legs syndrome, parasomnias, and circadian rhythm disorders. In addition to his clinical activities, Dr. Ruoff is active in research and education, providing mentorship to medical students. He has authored and coauthored numerous publications on various topics within sleep medicine including sleep apnea and narcolepsy.