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Everything You Need to Know About Fatal Familial Insomnia

Jennifer Clements, MD, MSEd, NBHWCPatricia Pinto-Garcia, MD, MPH
Published on May 2, 2022

Key takeaways:

  • Fatal familial insomnia is a very rare, inherited condition that has no cure.

  • People with fatal familial insomnia experience trouble sleeping, confusion, and dementia. Eventually the condition leads to death. 

  • Fatal familial insomnia isn’t a sleep disorder, it’s a prion disease.

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If you struggle with insomnia, you may have wondered how long you can go without sleeping. You may be relieved to hear that new evidence shows typical insomnia won’t shorten your life. 

But there’s one type of insomnia that leads to death. It’s called “fatal familial insomnia,” and it’s incredibly rare. Let’s take a closer look at this unusual condition. 

What causes fatal familial insomnia?

Even though it has “insomnia” in its name, fatal familial insomnia isn’t a sleep disorder

Fatal familial insomnia is a type of brain illness that prions cause. Prions are misfolded proteins that can “infect” or transfer their misshapen forms onto normal proteins. When this happens, a person develops a prion disease.

Prion diseases lead to damage in the brain. In fatal familial insomnia, the thalamus and medulla oblongata (parts of the brain) slowly start to break down and eventually die. As this happens, people experience symptoms of fatal familial insomnia. The symptoms get worse as the brain gets sicker.

How common is fatal familial insomnia?

Fatal familial insomnia is extremely rare. People with fatal familial insomnia form prions because of a genetic mutation in their PRNP gene. 

That means fatal familial insomnia passes down from generation to generation within families. Only about 70 families in the entire world carry the mutation for fatal familial insomnia.

Very rarely, someone who doesn’t have the PRNP gene mutation can develop the prion disease that causes fatal insomnia. This is called “sporadic fatal insomnia” to differentiate it from fatal familial insomnia. But despite the differences in names, the symptoms and outcomes are the same. Only about two dozen cases of sporadic fatal insomnia have been reported.

What are the symptoms of fatal familial insomnia?

The most common symptom of fatal familial insomnia is a sleep disturbance — mainly trouble sleeping and insomnia. Other symptoms include:

People usually develop symptoms between 50 and 60 years old. Symptoms tend to get worse over 6 to 12 months. 

As time goes on, people have difficulty with balance and walking. And they develop more severe dementia, confusion, and even hallucinations. Within about 1 to 3 years, people die from this condition. 

It’s important to point out that the early symptoms of fatal familial insomnia aren’t specific and can happen with many other conditions. So if you’re experiencing trouble sleeping, talk to your healthcare provider. It’s likely that there’s a different, more common reason for your symptoms.

How do you diagnose fatal familial insomnia?

Diagnosing fatal familial insomnia can be challenging because the condition is so rare. And the symptoms can be similar to those in other conditions. 

Experts developed a set of criteria that helps determine which people should have testing for fatal familial insomnia. If someone meets these criteria, healthcare providers will order tests to confirm the diagnosis. These tests can include: 

Is there a cure for fatal familial insomnia?

There’s no cure for fatal familial insomnia. As the name implies, there’s no way to survive the condition. On average, people live with the condition for 18 months. 

Medication can help ease symptoms. Healthcare providers can offer medication to help manage seizures and muscle spasms. Sleep aid medication can be helpful for some people with fatal familial insomnia, but it doesn’t work for everyone.

The bottom line

Fatal familial insomnia is a prion disease that affects the brain. People with fatal familial insomnia experience inability to sleep and rapid progression of dementia. There’s no treatment or cure for fatal familial insomnia. The condition is extremely rare — only about 70 families carry the gene for the condition and there are reports of only about 25 sporadic cases.


Centers for Disease Control and Prevention. (2014). Key sleep disorders.

Centers for Disease Control and Prevention. (2021). Prion diseases.

View All References (8)

Cracco, L., et al. (2018). Fatal familial insomnia and sporadic fatal insomnia. Handbook of Clinical Neurology.

Genetic Testing Registry. (2021). Fatal familial insomnia. National Center for Biotechnology Information.

Khan, Z., et al. (2022). Fatal familial insomnia. StatPearls.

Lovato, N., et al. (2019). Insomnia and mortality: A meta-analysis. Sleep Medicine Reviews.

Mehta, L. R., et al. (2008). Sporadic fatal insomnia masquerading as a paraneoplastic cerebellar syndrome. Archives of Neurology.

National Organization for Rare Disorders. (2018). Fatal familial insomnia.

ScienceDirect. (n.d.). Prion protein.

Wu, L. Y., et al. (2018). Expert consensus on clinical diagnostic criteria for fatal familial insomnia. Chinese Medical Journal.

GoodRx Health has strict sourcing policies and relies on primary sources such as medical organizations, governmental agencies, academic institutions, and peer-reviewed scientific journals. Learn more about how we ensure our content is accurate, thorough, and unbiased by reading our editorial guidelines.

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