What distinguishes narcolepsy type 1 from type 2?

Reviewed by Yoshinori Abe, MD

Internal Medicine

Narcolepsy type 1 differs from narcolepsy type 2 in two key ways:

Cataplexy: People with narcolepsy type 1 may experience cataplexy—sudden episodes of muscle weakness triggered by strong emotions. This does not occur in narcolepsy type 2.
Low hypocretin levels: Narcolepsy type 1 involves low levels of hypocretin, a brain chemical that regulates wakefulness (even in those without cataplexy). Hypocretin levels remain normal in narcolepsy type 2.

If you're experiencing excessive daytime sleepiness, sudden muscle weakness, or other unexplained symptoms, understanding the possible cause is the first step toward getting the right care. Take a free, instant, online symptom check to better understand what may be going on and confidently navigate your next steps.

Reviewed for medical accuracy: 07/14/2026

Important Next Steps

Learn if narcolepsy type 1 fits you Discover whether your sleepiness suggests narcolepsy See if your symptoms point to narcolepsy Find OTC options for daytime sleepiness Find a sleep specialist for narcolepsy care Discover home remedies for narcolepsy symptoms Understand whether cataplexy indicates narcolepsy type 1

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Explanation

Narcolepsy is a sleep disorder. There are two main types: narcolepsy type 1 and narcolepsy type 2.

Narcolepsy Type 1:

This type of narcolepsy can include a symptom called cataplexy, which is when strong emotions can rapidly lead to sudden muscle weakness. For example, laughing, surprise, or anger might make someone with narcolepsy type 1 suddenly have slurred speech, feel weak, or fall.
People with narcolepsy type 1 also have low levels of a brain chemical called hypocretin, which affects sleepiness and wakefulness. People with low levels of hypocretin have narcolepsy type 1, even if they do not have cataplexy.

Narcolepsy Type 2:

This type of narcolepsy does not include cataplexy (episodes of sudden muscle weakness usually triggered by strong emotions).
Brain hypocretin levels in people with narcolepsy type 2 are usually normal.

Both types of narcolepsy can cause excessive daytime sleepiness, which means feeling very sleepy during the day even after a good night's sleep. If you or someone you know is experiencing these symptoms, you can start by taking a free symptom checker test to better understand what might be causing your symptoms, and then consult with a healthcare provider for a personalized medical assessment and treatment plan.

(References)

Gandhi K, & Ferdous S. (2024). Tetrad of Narcolepsy Type 1: Treatment and Management. Cureus, 38562323.
Bassetti CLA, Adamantidis A, Burdakov D, Han F, Gay S, Kallweit U, et al. (2019). Narcolepsy - clinical spectrum, aetiopathophysiology, .... Nature reviews. Neurology, 31324898.
Zhang Z, Mayer G, Dauvilliers Y, Plazzi G, Pizza F, Fronczek R, et al. (2018). Exploring the clinical features of narcolepsy type 1 versus .... Scientific reports, 30006563.

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