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Is There A Connection Between Hypothyroidism and Narcolepsy?

Learn about the connection between hypothyroidism and narcolepsy.
Is There A Connection Between Hypothyroidism and Narcolepsy?
Last updated:
1/3/2023
Medically Reviewed by:

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Did you know that 14% of those diagnosed with hypothyroidism have narcolepsy? Narcolepsy affects your brain while hypothyroidism affects your thyroid gland. So, how can two very different medical conditions that affect different parts of your body be connected?

 

In this article, we are going to look at that connection. To help us understand the connection, let’s first get a better understanding of narcolepsy and hypothyroidism.

Understanding narcolepsy

Narcolepsy is a neurologic condition where your brain is unable to control your sleeping and waking patterns. Because of this, people with narcolepsy will experience excessive daytime sleepiness. This is described as always feeling tired no matter how much sleep they get. Other symptoms that might be present include: 

  • Sleep attacks or sudden onset of sleepiness 
  • Cataplexy or temporary loss of muscle tone 
  • Sleep paralysis or the inability to move or speak while falling asleep or waking up
  • Hallucinations

Cataplexy and sleep paralysis can last from seconds to minutes and will resolve on their own. A person with narcolepsy tends to fall asleep in the middle of an activity such as driving, talking, or eating. In between sleeping, people with narcolepsy are alert.  

Types of narcolepsy

There are 2 types of narcolepsy: type 1 and type 2. In both types, people with narcolepsy will experience excessive daytime sleepiness. But the difference is that some may experience cataplexy while others will have low or normal levels of a hormone called hypocretin. 

What is hypocretin?

Hypocretin also known as orexin regulates your sleep-wake cycle. Your hypothalamus, located in your brain, makes hypocretin and releases it into your brain and spinal fluid. Most people with narcolepsy have low levels of hypocretin in their spinal fluid. Because of this, researchers believe low levels of hypocretin cause intermittent wake and sleep states. 

Understanding hypothyroidism

Thyroid hormone is essential for our growth and development, body temperature regulation, and metabolism. Every cell and organ in your body needs thyroid hormone to function. Four different hormones regulate the making and release of thyroid hormone.






Your hypothalamus releases thyrotropin-releasing hormone (TRH) which tells your pituitary gland to release thyroid-stimulating hormone (TSH). This signals your thyroid gland, located at the bottom of your neck, to release triiodothyronine (T3) and thyroxine (T4). These two hormones will circulate throughout your bloodstream. When the levels of T3 and T4 become low, your hypothalamus releases TRH and the cycle starts again.

Any changes in this cycle affect the release of thyroid hormone. Hyperthyroidism is when too much is released whereas too little is a condition called hypothyroidism. When your thyroid hormone levels are low, your body slows down because it doesn’t have enough to meet your body’s demands. Thus, causing symptoms of hypothyroidism.

Symptoms of narcolepsy and hypothyroidism

While each condition has its own defining sets of symptoms, there are symptoms they share.

Connection between narcolepsy and hypothyroidism

Besides sharing symptoms, narcolepsy and hypothyroidism have two other common factors.

  1. Hypothalamus involvement
  2. Autoimmune disease

Let’s take a closer look at these.

The hypothalamus connection

The hypothalamus, an area in your brain, produces hormones that control:

  • Sleep
  • Hunger
  • Mood
  • Release of another hormone from other glands
  • Body temperature

Two of these hormones your hypothalamus produces are hypocretin and TRH. To review, hypocretin regulates your sleep-wake cycle and TRH stimulates the release of TSH which ultimately leads to the release of thyroid hormones

Even though the connection is not fully understood between hypocretin and thyroid hormones, current research suggests that one does affect the other. One study showed that people with narcolepsy had TRH deficiency. Thus preventing the release of TSH.  

A 2005 study concluded that people with narcolepsy who had a low level of hypocretin also had low levels of TSH. Researchers believed this to be because sleep prevents TSH from being released. The longer you sleep the lower your TSH levels.

But, what triggers these changes in the hypothalamus, to begin with?  

The autoimmune connection

An autoimmune disorder is where your immune system mistakenly starts attacking healthy cells in your body. This attack damages your cells, preventing them from functioning correctly. Having one autoimmune disorder puts you at risk of developing other ones. It is not unusual for someone to have more than one autoimmune disorder

In narcolepsy, especially type 1, a decrease in hypocretin is due to the death or loss of hypocretin-releasing brain cells. Without enough hypocretin, your body will have trouble regulating your sleep-wake cycle. There is still a debate about what causes the death of the hypocretin-releasing brain cells. But evidence strongly suggests that it is due to an autoimmune disorder. 

Hashimoto’s thyroiditis is a well-known autoimmune disease that causes hypothyroidism. It occurs when your body attacks your thyroid gland, destroying it. Because of this, your thyroid gland is not able to produce enough thyroid hormone. In response to low thyroid hormone levels, your body releases more TSH in the hopes that your thyroid gland will release thyroid hormone. But, your thyroid gland can’t because of the damage to it.

Will thyroid hormone medications make narcolepsy go away?

There are very few studies about thyroid hormone medications and the effect it has on symptoms of narcolepsy. Instead, most of the information comes from case reports. 

In a 2014 case report a woman that had normal thyroid function had improvement in total sleep and excessive daytime sleepiness after starting levothyroxine. A pediatric case report showed improvement in sleep symptoms when thyroid replacement therapy was added to their narcoleptic medication regimen.

A note from Paloma

Knowing your thyroid levels is the first step to knowing if hypothyroidism is causing your sleepiness. Paloma’s convenient at home test is easy to use and will have your results back within days. Consider scheduling a virtual visit with one of Paloma’s thyroid practitioners to help you interrupt your results.

Dealing with Hypothyroidism?  Video chat with a thyroid doctor

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References:

Alhajri S, Lee H, Siddiqui AH, Perez-Colon S. Isolated Central Hypothyroidism in an Adolescent With Narcolepsy. Cureus. Published online June 7, 2020. doi:10.7759/cureus.8496

Narcolepsy: MedlinePlus Genetics. medlineplus.gov.
https://medlineplus.gov/genetics/condition/narcolepsy/

Narcolepsy Fact Sheet | National Institute of Neurological Disorders and Stroke. www.ninds.nih.gov.
https://www.ninds.nih.gov/narcolepsy-fact-sheet

Slowik JM, Yow AG. Narcolepsy. Nih.gov. Published May 5, 2019.
https://www.ncbi.nlm.nih.gov/books/NBK459236/

Blaivas AJ, Bunting K. Hypothyroidism and Narcolepsy: Is There a Connection? Mynarcolepsyteam.com. Published March 21, 2022. Accessed November 6, 2022. https://www.mynarcolepsyteam.com/resources/hypothyroidism-and-narcolepsy-is-there-a-connection

Hypothalamus: MedlinePlus Medical Encyclopedia. Medlineplus.gov. Published 2016.
https://medlineplus.gov/ency/article/002380.htm

Kok SW, Roelfsema F, Overeem S, et al. Altered setting of the pituitary-thyroid ensemble in hypocretin-deficient narcoleptic men. American Journal of Physiology-Endocrinology and Metabolism. 2005;288(5):E892-E899. doi:10.1152/ajpendo.00327.2004

Post - Psycho-Neuro-Endocrinology Post. Integrative Psychiatrist. Accessed November 6, 2022. https://www.psychoneuroendocrinology.com/blog/2017/2/26/hashimotos-thyroiditis-autoimmune-diseases-and-the-brain

Kornum BR. Narcolepsy type 1: what have we learned from immunology? Sleep. Published online March 28, 2020. doi:10.1093/sleep/zsaa055

Sobol DL, Spector AR. Levothyroxine Improves Subjective Sleepiness in a Euthyroid Patient with Narcolepsy without Cataplexy. Journal of Clinical Sleep Medicine. 2014;10(11):1231-1232. doi:10.5664/jcsm.4210

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Emilie White, PharmD

Clinical Pharmacist and Medical Blogger

Emilie White, PharmD is a clinical pharmacist with over a decade of providing direct patient care to those hospitalized. She received her Doctor of Pharmacy degree from Massachusetts College of Pharmacy and Health Sciences. After graduation, Emilie completed a postgraduate pharmacy residency at Bon Secours Memorial Regional Medical Center in Virginia. Her background includes caring for critical care, internal medicine, and surgical patients.

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