Causes and Risk Factors of Narcolepsy

Table of Contents
View All
Table of Contents

A relatively rare condition, narcolepsy is a neurological disorder that causes extreme daytime sleepiness (EDS), which is an inability to stay awake and bouts of uncontrolled drowsiness. While the exact causes of this condition are unknown, it has been linked to deficits of a certain chemical, hypocretin, in the hypothalamus of the brain.

This neuropeptide, or brain protein, helps regulate sleep and wake cycles, among other functions. Research has shown that most narcoleptic people have severely reduced amounts of the brain cells that secrete hypocretin.

The reasons for reductions in these cells aren’t entirely clear, though research points to narcolepsy being an autoimmune disorder in which the immune system attacks the body’s cells. These kinds of disorders typically have a genetic component, so heredity is also likely to be a factor in narcolepsy.  

Excessive daytime sleepiness in narcolepsy

PhotoAlto/Frederic Cirou / Getty Images

Common Causes

There are three types of narcolepsy, and though there are still questions as to their exact causes, researchers have started finding answers. Each type seems to have differing causes. Here’s a quick breakdown.

Type 1 Narcolepsy

Type 1 narcolepsy is also known as narcolepsy with cataplexy. In these cases, EDS and other symptoms are accompanied by temporary bouts of muscle weakness and inability to move.

Researchers have found that those with this type have 80 to 90% of hypocretin emitting neurons missing from the hypothalamus, which is the part of the brain that regulates sleep cycles, hunger, and body temperature. Evidence is growing that these reductions are due to an autoimmune disorder in which the body’s immune system attacks these cells.

Type 2 Narcolepsy   

Type 2 narcolepsy is narcolepsy without cataplexy, and it’s typically not as severe. The deficiency of hypocretin is not as severe in these cases. Doctors still don’t know what, exactly, causes this form. Generally, a genetic component is suspected in this and type 1 narcolepsy.

Secondary Narcolepsy

Secondary narcolepsy is a type of narcolepsy that arises due to injury to the hypothalamus as can happen in a car accident or fall; in rare cases, this can also result from a brain tumor. In these cases, narcolepsy symptoms accompany other neurological issues, with patients often requiring over 10 hours of sleep.

Genetics

Both type 1 and type 2 narcolepsy are believed to have a significant genetic component, though the exact nature of that connection is still being explored. What is known is that up to 10% of people with type 1 narcolepsy have family members with it. Beyond that, researchers have isolated several genetic features that play a role in the formation of narcolepsy.

T-Cell Receptor Genes

T-cell receptor genes, which help regulate immune T-cells in the body, are known to be related to narcolepsy. Changes in the function of T-cell receptor alpha and beta, specifically, create a genetic predisposition for this condition.

This means that alterations found here increase the chances of developing narcolepsy or passing it along to offspring but aren’t necessarily causal factors on their own.

Human Leukocyte Antigen Genes

Most influential is the human leukocyte antigen (HLA) gene, DQB1*06:02, which increases the risk of developing type 1 narcolepsy 20 times while also being instrumental for type 2. Other HLA genes, notably DRB1*15:01, may also play a role in type 1 narcolepsy.

These genes trigger an immune response against the body's own components, which is why this disease is considered an autoimmune disorder. Research is ongoing to ascertain the exact nature of this link, though it’s believed that these specifically attack hypocretin-emitting brain cells.

Lifestyle Risk Factors

Generally speaking, specific behaviors or habits aren’t linked to the development of narcolepsy; however, they can increase the severity of symptoms. Specifically, there are several lifestyle changes that can help:

  • Keep a regular sleep schedule.
  • Take regular, daily naps.
  • Steer clear of caffeine or alcohol before bed.
  • Quit smoking cigarettes or ingesting nicotine.
  • Get daily exercise (a minimum of 20 minutes of activity a day).
  • Don’t eat large meals before bed.

A Word From Verywell

One of the current challenges facing medicine involves learning more about the causes of narcolepsy. With a better understanding of both the underlying genetic factors and the others that are associated with this condition, there’s no doubt that treatment approaches will continue to be developed.

Until there is a definitive cure, though, know that narcolepsy can be effectively managed. A number of medications can help, alongside changes to lifestyle habits.

But what’s perhaps even more important, if you’re narcoleptic, is to ensure that you’ve got a good support system. Remember that you have others in your corner: from your doctor and sleep specialist to your family, loved ones, and friends.

Was this page helpful?
Article Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. National Organization of Rare Disorders. Narcolepsy. Updated 2017.

  2. National Institute of Neurological Disorders and Stroke. Narcolepsy fact sheet. Updated 2020.

  3. Gauci S, Hosking W, Bruck D. Narcolepsy, cataplexy, hypocretin and co-existing other health complaints: A reviewCogent Medicine. 2017;4:1. doi:10.1080/2331205X.2017.1312791

  4. Saariaho AH, Vuorela A, Freitag TL, Pizza F, Plazzi G, Partinen M, Vaarala O, Meri S. Autoantibodies against ganglioside GM3 are associated with narcolepsy-cataplexy developing after Pandemrix vaccination against 2009 pandemic H1N1 type influenza virus. J Autoimmun. 2015 Sep;63:68-75. doi:10.1016/j.jaut.2015.07.006

  5. Ollila H. Narcolepsy type 1: what have we learned from genetics?. Sleep. 2020;43(11).